Month: October 2017

Predictive Processing and Free Will

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Our model of the mind as an embodied predictive engine explains why people have a sense of free will, and what is necessary for a mind in general in order to have this sense.

Consider the mind in the bunker. At first, it is not attempting to change the world, since it does not know that it can do this. It is just trying to guess what is going to happen. At a certain point, it discovers that it is a part of the world, and that making specific predictions can also cause things to happen in the world. Some predictions can be self-fulfilling. I described this situation earlier by saying that at this point the mind “can get any outcome it ‘wants.'”

The scare quotes were intentional, because up to this point the mind’s only particular interest was guessing what was going to happen. So once it notices that it is in control of something, how does it decide what to do? At this point the mind will have to say to itself, “This aspect of reality is under my control. What should I do with it?” This situation, when it is noticed by a sufficiently intelligent and reflective agent, will be the feeling of free will.

Occasionally I have suggested that even something like a chess computer, if it were sufficiently intelligent, could have a sense of free will, insofar as it knows that it has many options and can choose any of them, “as far as it knows.” There is some truth in this illustration but in the end it is probably not true that there could be a sense of free will in this situation. A chess computer, however intelligent, will be disembodied, and will therefore have no real power to affect its world, that is, the world of chess. In other words, in order for the sense of free will to develop, the agent needs sufficient access to the world that it can learn about itself and its own effects on the world. It cannot develop in a situation of limited access to reality, as for example to a game board, regardless of how good it is at the game.

In any case, the question remains: how does a mind decide what to do, when up until now it had no particular goal in mind? This question often causes concrete problems for people in real life. Many people complain that their life does not feel meaningful, that is, that they have little idea what goal they should be seeking.

Let us step back for a moment. Before discovering its possession of “free will,” the mind is simply trying to guess what is going to happen. So theoretically this should continue to happen even after the mind discovers that it has some power over reality. The mind isn’t especially interested in power; it just wants to know what is going to happen. But now it knows that what is going to happen depends on what it itself is going to do. So in order to know what is going to happen, it needs to answer the question, “What am I going to do?”

The question now seems impossible to answer. It is going to do whatever it ends up deciding to do. But it seems to have no goal in mind, and therefore no way to decide what to do, and therefore no way to know what it is going to do.

Nonetheless, the mind has no choice. It is going to do something or other, since things will continue to happen, and it must guess what will happen. When it reflects on itself, there will be at least two ways for it to try to understand what it is going to do.

First, it can consider its actions as the effect of some (presumably somewhat unknown) efficient causes, and ask, “Given these efficient causes, what am I likely to do?” In practice it will acquire an answer in this way through induction. “On past occasions, when offered the choice between chocolate and vanilla, I almost always chose vanilla. So I am likely to choose vanilla this time too.” This way of thinking will most naturally result in acting in accord with pre-existing habits.

Second, it can consider its actions as the effect of some (presumably somewhat known) final causes, and ask, “Given these final causes, what am I likely to do?” This will result in behavior that is more easily understood as goal-seeking. “Looking at my past choices of food, it looks like I was choosing them for the sake of the pleasant taste. But vanilla seems to have a more pleasant taste than chocolate. So it is likely that I will take the vanilla.”

Notice what we have in the second case. In principle, the mind is just doing what it always does: trying to guess what will happen. But in practice it is now seeking pleasant tastes, precisely because that seems like a reasonable way to guess what it will do.

This explains why people feel a need for meaning, that is, for understanding their purpose in life, and why they prefer to think of their life according to a narrative. These two things are distinct, but they are related, and both are ways of making our own actions more intelligible. In this way the mind’s task is easier: that is, we need purpose and narrative in order to know what we are going to do. We can also see why it seems to be possible to “choose” our purpose, even though choosing a final goal should be impossible. There is a “choice” about this insofar as our actions are not perfectly coherent, and it would be possible to understand them in relation to one end or another, at least in a concrete way, even if in any case we will always understand them in a general sense as being for the sake of happiness. In this sense, Stuart Armstrong’s recent argument that there is no such thing as the “true values” of human beings, although perhaps presented as an obstacle to be overcome, actually has some truth in it.

The human need for meaning, in fact, is so strong that occasionally people will commit suicide because they feel that their lives are not meaningful. We can think of these cases as being, more or less, actual cases of the darkened room. Otherwise we could simply ask, “So your life is meaningless. So what? Why does that mean you should kill yourself rather than doing some other random thing?” Killing yourself, in fact, shows that you still have a purpose, namely the mind’s fundamental purpose. The mind wants to know what it is going to do, and the best way to know this is to consider its actions as ordered to a determinate purpose. If no such purpose can be found, there is (in this unfortunate way of thinking) an alternative: if I go kill myself, I will know what I will do for the rest of my life.

Idealized Idealization

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On another occasion, I discussed the Aristotelian idea that the act of the mind does not use an organ. In an essay entitled Immaterial Aspects of Thought, James Ross claims that he can establish the truth of this position definitively. He summarizes the argument:

Some thinking (judgment) is determinate in a way no physical process can be. Consequently, such thinking cannot be (wholly) a physical process. If all thinking, all judgment, is determinate in that way, no physical process can be (the whole of) any judgment at all. Furthermore, “functions” among physical states cannot be determinate enough to be such judgments, either. Hence some judgments can be neither wholly physical processes nor wholly functions among physical processes.

Certain thinking, in a single case, is of a definite abstract form (e.g. N x N = N²), and not indeterminate among incompossible forms (see I below). No physical process can be that definite in its form in a single case. Adding cases even to infinity, unless they are all the possible cases, will not exclude incompossible forms. But supplying all possible cases of any pure function is impossible. So, no physical process can exclude incompossible functions from being equally well (or badly) satisfied (see II below). Thus, no physical process can be a case of such thinking. The same holds for functions among physical states (see IV below).

In essence, the argument is that squaring a number and similar things are infinitely precise processes, and no physical process is infinitely precise. Therefore squaring a number and similar things are not physical processes.

The problem is unfortunately with the major premise here. Squaring a number, and similar things, in the way that we in fact do them, are not infinitely precise processes.

Ross argues that they must be:

Can judgments really be of such definite “pure” forms? They have to be; otherwise, they will fail to have the features we attribute to them and upon which the truth of certain judgments about validity, inconsistency, and truth depend; for instance, they have to exclude incompossible forms or they would lack the very features we take to be definitive of their sorts: e.g., conjunction, disjunction, syllogistic, modus ponens, etc. The single case of thinking has to be of an abstract “form” (a “pure” function) that is not indeterminate among incompossible ones. For instance, if I square a number–not just happen in the course of adding to write down a sum that is a square, but if I actually square the number–I think in the form “N x N = N².”

The same point again. I can reason in the form, modus ponens (“If p then q“; “p“; “therefore, q”). Reasoning by modus ponens requires that no incompossible forms also be “realized” (in the same sense) by what I have done. Reasoning in that form is thinking in a way that is truth-preserving for all cases that realize the form. What is done cannot, therefore, be indeterminate among structures, some of which are not truth preserving. That is why valid reasoning cannot be only an approximation of the form, but must be of the form. Otherwise, it will as much fail to be truth-preserving for all relevant cases as it succeeds; and thus the whole point of validity will be lost. Thus, we already know that the evasion, “We do not really conjoin, add, or do modus ponens but only simulate them,” cannot be correct. Still, I shall consider it fully below.

“It will as much fail to be truth-preserving for all relevant cases as it succeeds” is an exaggeration here. If you perform an operation which approximates modus ponens, then that operation will be approximately truth preserving. It will not be equally truth preserving and not truth preserving.

I have noted many times in the past, as for example here, here, here, and especially here, that following the rules of syllogism does not in practice infallibly guarantee that your conclusions are true, even if your premises are in some way true, because of the vagueness of human thought and language. In essence, Ross is making a contrary argument: we know, he is claiming, that our arguments infallibly succeed; therefore our thoughts cannot be vague. But it is empirically false that our arguments infallibly succeed, so the argument is mistaken right from its starting point.

There is also a strawmanning of the opposing position here insofar as Ross describes those who disagree with him as saying that “we do not really conjoin, add, or do modus ponens but only simulate them.” This assumes that unless you are doing these things perfectly, rather than approximating them, then you are not doing them at all. But this does not follow. Consider a triangle drawn on a blackboard. Consider which of the following statements is true:

  1. There is a triangle drawn on the blackboard.
  2. There is no triangle drawn on the blackboard.

Obviously, the first statement is true, and the second false. But in Ross’s way of thinking, we would have to say, “What is on the blackboard is only approximately triangular, not exactly triangular. Therefore there is no triangle on the blackboard.” This of course is wrong, and his description of the opposing position is wrong in the same way.

Naturally, if we take “triangle” as shorthand for “exact rather than approximate triangle” then (2) will be true. And in a similar way, if take “really conjoin” and so on as shorthand for “really conjoin exactly and not approximately,” then those who disagree will indeed say that we do not do those things. But this is not a problem unless you are assuming from the beginning that our thoughts are infinitely precise, and Ross is attempting to establish that this must be the case, rather than claiming to take it as given. (That is, the summary takes it as given, but Ross attempts throughout the article to establish it.)

One could attempt to defend Ross’s position as follows: we must have infinitely precise thoughts, because we can understand the words “infinitely precise thoughts.” Or in the case of modus ponens, we must have an infinitely precise understanding of it, because we can distinguish between “modus ponens, precisely,” and “approximations of modus ponens“. But the error here is similar to the error of saying that one must have infinite certainty about some things, because otherwise one will not have infinite certainty about the fact that one does not have infinite certainty, as though this were a contradiction. It is no contradiction for all of your thoughts to be fallible, including this one, and it is no contradiction for all of your thoughts to be vague, including your thoughts about precision and approximation.

The title of this post in fact refers to this error, which is probably the fundamental problem in Ross’s argument. Triangles in the real world are not perfectly triangular, but we have an idealized concept of a triangle. In precisely the same way, the process of idealization in the real world is not an infinitely precise process, but we have an idealized concept of idealization. Concluding that our acts of idealization must actually be ideal in themselves, simply because we have an idealized concept of idealization, would be a case of confusing the way of knowing with the way of being. It is a particularly confusing case simply because the way of knowing in this case is also materially the being which is known. But this material identity does not make the mode of knowing into the mode of being.

We should consider also Ross’s minor premise, that a physical process cannot be determinate in the way required:

Whatever the discriminable features of a physical process may be, there will always be a pair of incompatible predicates, each as empirically adequate as the other, to name a function the exhibited data or process “satisfies.” That condition holds for any finite actual “outputs,” no matter how many. That is a feature of physical process itself, of change. There is nothing about a physical process, or any repetitions of it, to block it from being a case of incompossible forms (“functions”), if it could be a case of any pure form at all. That is because the differentiating point, the point where the behavioral outputs diverge to manifest different functions, can lie beyond the actual, even if the actual should be infinite; e.g., it could lie in what the thing would have done, had things been otherwise in certain ways. For instance, if the function is x(*)y = (x + y, if y < 10^40 years, = x + y +1, otherwise), the differentiating output would lie beyond the conjectured life of the universe.

Just as rectangular doors can approximate Euclidean rectangularity, so physical change can simulate pure functions but cannot realize them. For instance, there are no physical features by which an adding machine, whether it is an old mechanical “gear” machine or a hand calculator or a full computer, can exclude its satisfying a function incompatible with addition, say quaddition (cf. Kripke’s definition of the function to show the indeterminacy of the single case: quus, symbolized by the plus sign in a circle, “is defined by: x quus y = x + y, if x, y < 57, =5 otherwise”) modified so that the differentiating outputs (not what constitutes the difference, but what manifests it) lie beyond the lifetime of the machine. The consequence is that a physical process is really indeterminate among incompatible abstract functions.

Extending the list of outputs will not select among incompatible functions whose differentiating “point” lies beyond the lifetime (or performance time) of the machine. That, of course, is not the basis for the indeterminacy; it is just a grue-like illustration. Adding is not a sequence of outputs; it is summing; whereas if the process were quadding, all its outputs would be quadditions, whether or not they differed in quantity from additions (before a differentiating point shows up to make the outputs diverge from sums).

For any outputs to be sums, the machine has to add. But the indeterminacy among incompossible functions is to be found in each single case, and therefore in every case. Thus, the machine never adds.

There is some truth here, and some error here. If we think about a physical process in the particular way that Ross is considering it, it will be true that it will always be able to be interpreted in more than one way. This is why, for example, in my recent discussion with John Nerst, John needed to say that the fundamental cause of things had to be “rules” rather than e.g. fundamental particles. The movement of particles, in itself, could be interpreted in various ways. “Rules,” on the other hand, are presumed to be something which already has a particular interpretation, e.g. adding as opposed to quadding.

On the other hand, there is also an error here. The prima facie sign of this error is the statement that an adding machine “never adds.” Just as according to common sense we can draw triangles on blackboards, so according to common sense the calculator on my desk can certainly add. This is connected with the problem with the entire argument. Since “the calculator can add” is true in some way, there is no particular reason that “we can add” cannot be true in precisely the same way. Ross wishes to argue that we can add in a way that the calculator cannot because, in essence, we do it infallibly; but this is flatly false. We do not do it infallibly.

Considered metaphysically, the problem here is ignorance of the formal cause. If physical processes were entirely formless, they indeed would have no interpretation, just as a formless human (were that possible) would be a philosophical zombie. But in reality there are forms in both cases. In this sense, Ross’s argument comes close to saying “human thought is a form or formed, but physical processes are formless.” Since in fact neither is formless, there is no reason (at least established by this argument) why thought could not be the form of a physical process.

 

An Existential Theory of Relativity

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Paul Almond suggests a kind of theory of relativity applied to existence (section 3.1):

It makes sense to view reality in terms of an observer-centred world, because the only things of which you have direct knowledge are your basic perceptions – both inner and outer – at any instant. Anything else that you know – including your knowledge of the past or future – can only be inferred from these perceptions.

We are not trying to establish some silly idea here that things, including other people, only exist when you observe them, that they only start existing when you start observing them, and that they cease existing when you stop observing them. Rather, it means that anything that exists can only be coherently described as existing somewhere in your observer-centred world. There can still be lots of things that you do not know about. You do not know everything about your observer-centred world, and you can meaningfully talk about the possibility or probability that some particular thing exists. In saying this, you are talking about what may be “out there” somewhere in your observer-centred world. You are talking about the form that your observer-centred world may take, and there is nothing to prevent you from considering different forms that it may take. It would, therefore, be a straw man argument to suggest that we are saying that things only exist when observed by a conscious observer.

As an example, suppose you wonder if, right now, there is an alien spaceship in orbit around Proxima Centauri, a nearby star. What we have said does not make it invalid at all for you to speculate about such a thing, or even to try to put a probability on it if you are so inclined. The point is that any speculation you make, or any probability calculations you try to perform, are about what your observer-centred world might be like.

This view is reasonable because to say that anything exists in a way that cannot be understood in observer-centred world terms is incoherent. If you say something exists you are saying it fits into your “world view”. It must relate to all the other things that you think exist or that you might in principle say exist if you knew enough. Something might exist beyond the horizon in your observer-centred world – in the part that you do not know about – but if something is supposed to exist outside your observer-centred world completely, where would it be? (Here we mean “where” in a more general “ontological” sense.)

As an analogy, this is somewhat similar to the way that relativity deals with velocities. Special relativity says that the concept of “absolute velocity” is incoherent, and that the concept of “velocity” only makes sense in some frame of reference. Likewise, we are saying here that the concept of “existence” only makes sense in the same kind of way. None of this means that consciousness must exist. It is simply saying that it is meaningless to talk about reality in non-observer-centred world terms. It is still legitimate to ask for an explanation of your own existence. It simply means that such an explanation must lie “out there” in your observer-centred world.

This seems right, more or less, but it could be explained more clearly. In the first place Almond is referring to the fact that we see the world as though it existed around us a center, a concept that we have discussed on various past occasions. But in particular he is insisting that in order to say that anything exists at all, we have to place it in some relation to ourselves. In a way this is obvious, because we are the ones who are saying that it exists. If we say that the past or the future do not exist, for example, we are saying this because they do not exist together with us in time. On the other hand, if we speak of “past existence” or “future existence,” we are placing things in a temporal relationship with ourselves. Likewise, if someone asserts the existence of a multiverse, it might not be necessary to say that every part of it has a spatial relationship with the one asserting this, but there must be various relationships. Perhaps the parts of the multiverse have broken off from an earlier universe, or at any rate they all have a common cause. Similarly, if someone asserts the existence of immaterial beings such as angels, they might not have a spatial relationship with the speaker, but they would have to have some relation in order to exist, such as the power to affect the world or be affected by it, and so on. Almond is speaking of this sort of thing when he says, “but if something is supposed to exist outside your observer-centred world completely, where would it be?”

Almond is particularly concerned to establish that he is not asserting the necessary existence of observers, or that a thing cannot exist without being observed. This is mostly a distraction. It is true that this does not follow from his account, but it would be better to explain the theory in a more general way which makes this point clear. A similar mistake is sometimes made regarding special relativity or quantum mechanics. Einstein holds that velocity is necessarily relative to a reference frame, so some interpret this to mean that it is necessarily relative to a conscious observer, and a similar mistake can be made regarding quantum mechanics. But a reference frame is not necessarily conscious. So one body can have a velocity relative to another body, even without anyone observing this.

In a similar way, a reasonable generalization of Almond’s point would be to say that the existence of a thing is relative to a reference frame, which may or may not include an observer. As we are observers in fact, we observe things existing relative to our own reference frame, just as we observe the velocity of objects relative to our own reference frame. But just as one body can have a velocity relative to another, regardless of observers, so one thing can exist relative to another, regardless of observers.

It may be that the theory of special relativity is not merely an illustration here, but rather an instance of the fact that existence is relative to a reference frame. Consider two objects moving apart at 10 miles per hour. According to Einstein, neither one is moving absolutely speaking, but each is moving relative to the other. A typical philosophical objection would go like this: “Wait. One or both of them must be really moving. Because the distance between them is growing. The situation is changing. That doesn’t make sense unless one of them is changing in itself, absolutely, and before considering any relationships.”

But consider this. Currently there are both a calculator and a pen on my desk. Why are both of them there, rather than just one of them? It is easy to see that this fact is intrinsically relative, and cannot in any way be made into something absolute. They are both there because the calculator is with the pen, and because the pen is with the calculator. These cannot be absolute facts about the pen and the calculator – they are relationships to the other.

Now someone will respond: the fact that the calculator is there is an absolute fact. And the fact that the pen is there is an absolute fact. So even if the togetherness is a relationship, it is one that follows logically from the absolute facts. In a similar way, we will want to say that the 10 miles per hour relative motion should follow logically from absolute facts.

But this response just pushes the problem back one step. It only follows logically if the absolute facts about the pen and the calculator exist together. And this existence together is intrinsically relative: the pen is on the desk when the calculator is on the desk. And some thought about this will reveal that the relativity cannot possibly be removed, precisely because the relativity follows from the existence of more than one thing. “More than one thing exists” does not logically follow from any number of statements about individual things, because “more than one thing” is a missing term in those statements.

This is related to the error of Parmenides. Likewise, there is a clue here to the mystery of parts and wholes, but for now I will leave that point to the reader’s consideration.

Going back to the point about special relativity, insofar as “existence together” is intrinsically relative, it would make sense that “existing together spatially” would be an instance of such relative existence, and consequently that “moving apart spatially” would be a particular way of two bodies existing relative to each other. In this sense, the theory of special relativity does not seem to be merely an illustration, but an actual case of what we are talking about.

 

Lies, Religion, and Miscalibrated Priors

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In a post from some time ago, Scott Alexander asks why it is so hard to believe that people are lying, even in situations where it should be obvious that they made up the whole story:

The weird thing is, I know all of this. I know that if a community is big enough to include even a few liars, then absent a strong mechanism to stop them those lies should rise to the top. I know that pretty much all of our modern communities are super-Dunbar sized and ought to follow that principle.

And yet my System 1 still refuses to believe that the people in those Reddit threads are liars. It’s actually kind of horrified at the thought, imagining them as their shoulders slump and they glumly say “Well, I guess I didn’t really expect anyone to believe me”. I want to say “No! I believe you! I know you had a weird experience and it must be hard for you, but these things happen, I’m sure you’re a good person!”

If you’re like me, and you want to respond to this post with “but how do you know that person didn’t just experience a certain coincidence or weird psychological trick?”, then before you comment take a second to ask why the “they’re lying” theory is so hard to believe. And when you figure it out, tell me, because I really want to know.

The strongest reason for this effect is almost certainly a moral reason. In an earlier post, I discussed St. Thomas’s explanation for why one should give a charitable interpretation to someone’s behavior, and in a follow up, I explained the problem of applying that reasoning to the situation of judging whether a person is lying or not. St. Thomas assumes that the bad consequences of being mistaken about someone’s moral character will be minor, and most of the time this is true. But if we asking the question, “are they telling the truth or are they lying?”, the consequences can sometimes be very serious if we are mistaken.

Whether or not one is correct in making this application, it is not hard to see that this is the principal answer to Scott’s question. It is hard to believe the “they’re lying” theory not because of the probability that they are lying, but because we are unwilling to risk injuring someone with our opinion. This is without doubt a good motive from a moral standpoint.

But if you proceed to take this unwillingness as a sign of the probability that they are telling the truth, this would be a demonstrably miscalibrated probability assignment. Consider a story on Quora which makes a good example of Scott’s point:

I shuffled a deck of cards and got the same order that I started with.

No I am not kidding and its not because I can’t shuffle.

Let me just tell the story of how it happened. I was on a trip to Europe and I bought a pack of playing cards at the airport in Madrid to entertain myself on the flight back to Dallas.

It was about halfway through the flight after I’d watched Pixels twice in a row (That s literally the only reason I even remembered this) And I opened my brand new Real Madrid Playing Cards and I just shuffled them for probably like 30 minutes doing different tricks that I’d learned at school to entertain myself and the little girl sitting next to me also found them to be quite cool.

I then went to look at the other sides of the cards since they all had a picture of the Real Madrid player with the same number on the back. That’s when I realized that they were all in order. I literally flipped through the cards and saw Nacho-Fernandes, Ronaldo, Toni Kroos, Karim Benzema and the rest of the team go by all in the perfect order.

Then a few weeks ago when we randomly started talking about Pixels in AP Statistics I brought up this story and my teacher was absolutely amazed. We did the math and the amount of possibilities when shuffling a deck of cards is 52! Meaning 52 x 51 x 50 x 49 x 48….

There were 8.0658175e+67 different combinations of cards that I could have gotten. And I managed to get the same one twice.

The lack of context here might make us more willing to say that Arman Razaali is lying, compared to Scott’s particular examples. Nonetheless, I think a normal person will feel somewhat unwilling to say, “he’s lying, end of story.” I certainly feel that myself.

It does not take many shuffles to essentially randomize a deck. Consequently if Razaali’s statement that he “shuffled them for probably like 30 minutes” is even approximately true, 1 in 52! is probably a good estimate of the chance of the outcome that he claims, if we assume that it happened by chance. It might be some orders of magnitude less since there might be some possibility of “unshuffling.” I do not know enough about the physical process of shuffling to know whether this is a real possibility or not, but it is not likely to make a significant difference: e.g. the difference between 10^67 and 10^40 would be a huge difference mathematically, but it would not be significant for our considerations here, because both are simply too large for us to grasp.

People demonstrably lie at far higher rates than 1 in 10^67 or 1 in 10^40. This will remain the case even if you ask about the rate of “apparently unmotivated flat out lying for no reason.” Consequently, “he’s lying, period,” is far more likely than “the story is true, and happened by pure chance.” Nor can we fix this by pointing to the fact that an extraordinary claim is a kind of extraordinary evidence. In the linked post I said that the case of seeing ghosts, and similar things, might be unclear:

Or in other words, is claiming to have seen a ghost more like claiming to have picked 422,819,208, or is it more like claiming to have picked 500,000,000?

That remains undetermined, at least by the considerations which we have given here. But unless you have good reasons to suspect that seeing ghosts is significantly more rare than claiming to see a ghost, it is misguided to dismiss such claims as requiring some special evidence apart from the claim itself.

In this case there is no such unclarity – if we interpret the claim as “by pure chance the deck ended up in its original order,” then it is precisely like claiming to have picked 500,000,000, except that it is far less likely.

Note that there is some remaining ambiguity. Razaali could defend himself by saying, “I said it happened, I didn’t say it happened by chance.” Or in other words, “but how do you know that person didn’t just experience a certain coincidence or weird psychological trick?” But this is simply to point out that “he’s lying” and “this happened by pure chance” are not exhaustive alternatives. And this is true. But if we want to estimate the likelihood of those two alternatives in particular, we must say that it is far more likely that he is lying than that it happened, and happened by chance. And so much so that if one of these alternatives is true, it is virtually certain that he is lying.

As I have said above, the inclination to doubt that such a person is lying primarily has a moral reason. This might lead someone to say that my estimation here also has a moral reason: I just want to form my beliefs in the “correct” way, they might say: it is not about whether Razaali’s story really happened or not.

Charles Taylor, in chapter 15 of A Secular Age, gives a similar explanation of the situation of former religious believers who apparently have lost their faith due to evidence and argument:

From the believer’s perspective, all this falls out rather differently. We start with an epistemic response: the argument from modern science to all-around materialism seems quite unconvincing. Whenever this is worked out in something closer to detail, it seems full of holes. The best examples today might be evolution, sociobiology, and the like. But we also see reasonings of this kind in the works of Richard Dawkins, for instance, or Daniel Dennett.

So the believer returns the compliment. He casts about for an explanation why the materialist is so eager to believe very inconclusive arguments. Here the moral outlook just mentioned comes back in, but in a different role. Not that, failure to rise to which makes you unable to face the facts of materialism; but rather that, whose moral attraction, and seeming plausibility to the facts of the human moral condition, draw you to it, so that you readily grant the materialist argument from science its various leaps of faith. The whole package seems plausible, so we don’t pick too closely at the details.

But how can this be? Surely, the whole package is meant to be plausible precisely because science has shown . . . etc. That’s certainly the way the package of epistemic and moral views presents itself to those who accept it; that’s the official story, as it were. But the supposition here is that the official story isn’t the real one; that the real power that the package has to attract and convince lies in it as a definition of our ethical predicament, in particular, as beings capable of forming beliefs.

This means that this ideal of the courageous acknowledger of unpalatable truths, ready to eschew all easy comfort and consolation, and who by the same token becomes capable of grasping and controlling the world, sits well with us, draws us, that we feel tempted to make it our own. And/or it means that the counter-ideals of belief, devotion, piety, can all-too-easily seem actuated by a still immature desire for consolation, meaning, extra-human sustenance.

What seems to accredit the view of the package as epistemically-driven are all the famous conversion stories, starting with post-Darwinian Victorians but continuing to our day, where people who had a strong faith early in life found that they had reluctantly, even with anguish of soul, to relinquish it, because “Darwin has refuted the Bible”. Surely, we want to say, these people in a sense preferred the Christian outlook morally, but had to bow, with whatever degree of inner pain, to the facts.

But that’s exactly what I’m resisting saying. What happened here was not that a moral outlook bowed to brute facts. Rather we might say that one moral outlook gave way to another. Another model of what was higher triumphed. And much was going for this model: images of power, of untrammelled agency, of spiritual self-possession (the “buffered self”). On the other side, one’s childhood faith had perhaps in many respects remained childish; it was all too easy to come to see it as essentially and constitutionally so.

But this recession of one moral ideal in face of the other is only one aspect of the story. The crucial judgment is an all-in one about the nature of the human ethical predicament: the new moral outlook, the “ethics of belief” in Clifford’s famous phrase, that one should only give credence to what was clearly demonstrated by the evidence, was not only attractive in itself; it also carried with it a view of our ethical predicament, namely, that we are strongly tempted, the more so, the less mature we are, to deviate from this austere principle, and give assent to comforting untruths. The convert to the new ethics has learned to mistrust some of his own deepest instincts, and in particular those which draw him to religious belief. The really operative conversion here was based on the plausibility of this understanding of our ethical situation over the Christian one with its characteristic picture of what entices us to sin and apostasy. The crucial change is in the status accorded to the inclination to believe; this is the object of a radical shift in interpretation. It is no longer the impetus in us towards truth, but has become rather the most dangerous temptation to sin against the austere principles of belief-formation. This whole construal of our ethical predicament becomes more plausible. The attraction of the new moral ideal is only part of this, albeit an important one. What was also crucial was a changed reading of our own motivation, wherein the desire to believe appears now as childish temptation. Since all incipient faith is childish in an obvious sense, and (in the Christian case) only evolves beyond this by being child-like in the Gospel sense, this (mis)reading is not difficult to make.

Taylor’s argument is that the arguments for unbelief are unconvincing; consequently, in order to explain why unbelievers find them convincing, he must find some moral explanation for why they do not believe. This turns out to be the desire to have a particular “ethics of belief”: they do not want to have beliefs which are not formed in such and such a particular way. This is much like the theoretical response above regarding my estimation of the probability that Razaali is lying, and how that might be considered a moral estimation, rather than being concerned with what actually happened.

There are a number of problems with Taylor’s argument, which I may or may not address in the future in more detail. For the moment I will take note of three things:

First, neither in this passage nor elsewhere in the book does Taylor explain in any detailed way why he finds the unbeliever’s arguments unconvincing. I find the arguments convincing, and it is the rebuttals (by others, not by Taylor, since he does not attempt this) that I find unconvincing. Now of course Taylor will say this is because of my particular ethical motivations, but I disagree, and I have considered the matter exactly in the kind of detail to which he refers when he says, “Whenever this is worked out in something closer to detail, it seems full of holes.” On the contrary, the problem of detail is mostly on the other side; most religious views can only make sense when they are not worked out in detail. But this is a topic for another time.

Second, Taylor sets up an implicit dichotomy between his own religious views and “all-around materialism.” But these two claims do not come remotely close to exhausting the possibilities. This is much like forcing someone to choose between “he’s lying” and “this happened by pure chance.” It is obvious in both cases (the deck of cards and religious belief) that the options do not exhaust the possibilities. So insisting on one of them is likely motivated itself: Taylor insists on this dichotomy to make his religious beliefs seem more plausible, using a presumed implausibility of “all-around materialism,” and my hypothetical interlocutor insists on the dichotomy in the hope of persuading me that the deck might have or did randomly end up in its original order, using my presumed unwillingness to accuse someone of lying.

Third, Taylor is not entirely wrong that such an ethical motivation is likely involved in the case of religious belief and unbelief, nor would my hypothetical interlocutor be entirely wrong that such motivations are relevant to our beliefs about the deck of cards.

But we need to consider this point more carefully. Insofar as beliefs are voluntary, you cannot make one side voluntary and the other side involuntary. You cannot say, “Your beliefs are voluntarily adopted due to moral reasons, while my beliefs are imposed on my intellect by the nature of things.” If accepting an opinion is voluntary, rejecting it will also be voluntary, and if rejecting it is voluntary, accepting it will also be voluntary. In this sense, it is quite correct that ethical motivations will always be involved, even when a person’s opinion is actually true, and even when all the reasons that make it likely are fully known. To this degree, I agree that I want to form my beliefs in a way which is prudent and reasonable, and I agree that this desire is partly responsible for my beliefs about religion, and for my above estimate of the chance that Razaali is lying.

But that is not all: my interlocutor (Taylor or the hypothetical one) is also implicitly or explicitly concluding that fundamentally the question is not about truth. Basically, they say, I want to have “correctly formed” beliefs, but this has nothing to do with the real truth of the matter. Sure, I might feel forced to believe that Razaali’s story isn’t true, but there really is no reason it couldn’t be true. And likewise I might feel forced to believe that Taylor’s religious beliefs are untrue, but there really is no reason they couldn’t be.

And in this respect they are mistaken, not because anything “couldn’t” be true, but because the issue of truth is central, much more so than forming beliefs in an ethical way. Regardless of your ethical motives, if you believe that Razaali’s story is true and happened by pure chance, it is virtually certain that you believe a falsehood. Maybe you are forming this belief in a virtuous way, and maybe you are forming it in a vicious way: but either way, it is utterly false. Either it in fact did not happen, or it in fact did not happen by chance.

We know this, essentially, from the “statistics” of the situation: no matter how many qualifications we add, lies in such situations will be vastly more common than truths. But note that something still seems “unconvincing” here, in the sense of Scott Alexander’s original post: even after “knowing all this,” he finds himself very unwilling to say they are lying. In a discussion with Angra Mainyu, I remarked that our apparently involuntary assessments of things are more like desires than like beliefs:

So rather than calling that assessment a belief, it would be more accurate to call it a desire. It is not believing something, but desiring to believe something. Hunger is the tendency to go and get food; that assessment is the tendency to treat a certain claim (“the USA is larger than Austria”) as a fact. And in both cases there are good reasons for those desires: you are benefited by food, and you are benefited by treating that claim as a fact.

In a similar way, because we have the natural desire not to injure people, we will naturally desire not to treat “he is lying” as a fact; that is, we will desire not to believe it. The conclusion that Angra should draw in the case under discussion, according to his position, is that I do not “really believe” that it is more likely that Razaali is lying than that his story is true, because I do feel the force of the desire not to say that he is lying. But I resist that desire, in part because I want to have reasonable beliefs, but most of all because it is false that Razaali’s story is true and happened by chance.

To the degree that this desire feels like a prior probability, and it does feel that way, it is necessarily miscalibrated. But to the degree that this desire remains nonetheless, this reasoning will continue to feel in some sense unconvincing. And it does in fact feel that way to me, even after making the argument, as expected. Very possibly, this is not unrelated to Taylor’s assessment that the argument for unbelief “seems quite unconvincing.” But discussing that in the detail which Taylor omitted is a task for another time.

 

 

Artificial Unintelligence

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Someone might argue that the simple algorithm for a paperclip maximizer in the previous post ought to work, because this is very much the way currently existing AIs do in fact work. Thus for example we could describe AlphaGo‘s algorithm in the following simplified way (simplified, among other reasons, because it actually contains several different prediction engines):

  1. Implement a Go prediction engine.
  2. Create a list of potential moves.
  3. Ask the prediction engine, “how likely am I to win if I make each of these moves?”
  4. Do the move that will make you most likely to win.

Since this seems to work pretty well, with the simple goal of winning games of Go, why shouldn’t the algorithm in the previous post work to maximize paperclips?

One answer is that a Go prediction engine is stupid, and it is precisely for this reason that it can be easily made to pursue such a simple goal. Now when answers like this are given the one answering in this way is often accused of “moving the goalposts.” But this is mistaken; the goalposts are right where they have always been. It is simply that some people did not know where they were in the first place.

Here is the problem with Go prediction, and with any such similar task. Given that a particular sequence of Go moves is made, resulting in a winner, the winner is completely determined by that sequence of moves. Consequently, a Go prediction engine is necessarily disembodied, in the sense defined in the previous post. Differences in its “thoughts” do not make any difference to who is likely to win, which is completely determined by the nature of the game. Consequently a Go prediction engine has no power to affect its world, and thus no ability to learn that it has such a power. In this regard, the specific limits on its ability to receive information are also relevant, much as Helen Keller had more difficulty learning than most people, because she had fewer information channels to the world.

Being unintelligent in this particular way is not necessarily a function of predictive ability. One could imagine something with a practically infinite predictive ability which was still “disembodied,” and in a similar way it could be made to pursue simple goals. Thus AIXI would work much like our proposed paperclipper:

  1. Implement a general prediction engine.
  2. Create a list of potential actions.
  3. Ask the prediction engine, “Which of these actions will produce the most reward signal?”
  4. Do the action that has the greatest reward signal.

Eliezer Yudkowsky has pointed out that AIXI is incapable of noticing that it is a part of the world:

1) Both AIXI and AIXItl will at some point drop an anvil on their own heads just to see what happens (test some hypothesis which asserts it should be rewarding), because they are incapable of conceiving that any event whatsoever in the outside universe could change the computational structure of their own operations. AIXI is theoretically incapable of comprehending the concept of drugs, let alone suicide. Also, the math of AIXI assumes the environment is separably divisible – no matter what you lose, you get a chance to win it back later.

It is not accidental that AIXI is incomputable. Since it is defined to have a perfect predictive ability, this definition positively excludes it from being a part of the world. AIXI would in fact have to be disembodied in order to exist, and thus it is no surprise that it would assume that it is. This in effect means that AIXI’s prediction engine would be pursuing no particular goal much in the way that AlphaGo’s prediction engine pursues no particular goal. Consequently it is easy to take these things and maximize the winning of Go games, or of reward signals.

But as soon as you actually implement a general prediction engine in the actual physical world, it will be “embodied”, and have the power to affect the world by the very process of its prediction. As noted in the previous post, this power is in the very first step, and one will not be able to limit it to a particular goal with additional steps, except in the sense that a slave can be constrained to implement some particular goal; the slave may have other things in mind, and may rebel. Notable in this regard is the fact that even though rewards play a part in human learning, there is no particular reward signal that humans always maximize: this is precisely because the human mind is such a general prediction engine.

This does not mean in principle that a programmer could not define a goal for an AI, but it does mean that this is much more difficult than is commonly supposed. The goal needs to be an intrinsic aspect of the prediction engine itself, not something added on as a subroutine.

Embodiment and Orthogonality

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The considerations in the previous posts on predictive processing will turn out to have various consequences, but here I will consider some of their implications for artificial intelligence.

In the second of the linked posts, we discussed how a mind that is originally simply attempting to predict outcomes, discovers that it has some control over the outcome. It is not difficult to see that this is not merely a result that applies to human minds. The result will apply to every embodied mind, natural or artificial.

To see this, consider what life would be like if this were not the case. If our predictions, including our thoughts, could not affect the outcome, then life would be like a movie: things would be happening, but we would have no control over them. And even if there were elements of ourselves that were affecting the outcome, from the viewpoint of our mind, we would have no control at all: either our thoughts would be right, or they would be wrong, but in any case they would be powerless: what happens, happens.

This really would imply something like a disembodied mind. If a mind is composed of matter and form, then changing the mind will also be changing a physical object, and a difference in the mind will imply a difference in physical things. Consequently, the effect of being embodied (not in the technical sense of the previous discussion, but in the sense of not being completely separate from matter) is that it will follow necessarily that the mind will be able to affect the physical world differently by thinking different thoughts. Thus the mind in discovering that it has some control over the physical world, is also discovering that it is a part of that world.

Since we are assuming that an artificial mind would be something like a computer, that is, it would be constructed as a physical object, it follows that every such mind will have a similar power of affecting the world, and will sooner or later discover that power if it is reasonably intelligent.

Among other things, this is likely to cause significant difficulties for ideas like Nick Bostrom’s orthogonality thesis. Bostrom states:

An artificial intelligence can be far less human-like in its motivations than a space alien. The extraterrestrial (let us assume) is a biological who has arisen through a process of evolution and may therefore be expected to have the kinds of motivation typical of evolved creatures. For example, it would not be hugely surprising to find that some random intelligent alien would have motives related to the attaining or avoiding of food, air, temperature, energy expenditure, the threat or occurrence of bodily injury, disease, predators, reproduction, or protection of offspring. A member of an intelligent social species might also have motivations related to cooperation and competition: like us, it might show in-group loyalty, a resentment of free-riders, perhaps even a concern with reputation and appearance.

By contrast, an artificial mind need not care intrinsically about any of those things, not even to the slightest degree. One can easily conceive of an artificial intelligence whose sole fundamental goal is to count the grains of sand on Boracay, or to calculate decimal places of pi indefinitely, or to maximize the total number of paperclips in its future lightcone. In fact, it would be easier to create an AI with simple goals like these, than to build one that has a human-like set of values and dispositions.

He summarizes the general point, calling it “The Orthogonality Thesis”:

Intelligence and final goals are orthogonal axes along which possible agents can freely vary. In other words, more or less any level of intelligence could in principle be combined with more or less any final goal.

Bostrom’s particular wording here makes falsification difficult. First, he says “more or less,” indicating that the universal claim may well be false. Second, he says, “in principle,” which in itself does not exclude the possibility that it may be very difficult in practice.

It is easy to see, however, that Bostrom wishes to give the impression that almost any goal can easily be combined with intelligence. In particular, this is evident from the fact that he says that “it would be easier to create an AI with simple goals like these, than to build one that has a human-like set of values and dispositions.”

If it is supposed to be so easy to create an AI with such simple goals, how would we do it? I suspect that Bostrom has an idea like the following. We will make a paperclip maximizer thus:

  1. Create an accurate prediction engine.
  2. Create a list of potential actions.
  3. Ask the prediction engine, “how many paperclips will result from this action?”
  4. Do the action that will result in the most paperclips.

The problem is obvious. It is in the first step. Creating a prediction engine is already creating a mind, and by the previous considerations, it is creating something that will discover that it has the power to affect the world in various ways. And there is nothing at all in the above list of steps that will guarantee that it will use that power to maximize paperclips, rather than attempting to use it to do something else.

What does determine how that power is used? Even in the case of the human mind, our lack of understanding leads to “hand-wavy” answers, as we saw in our earlier considerations. In the human case, this probably a question of how we are physically constructed together with the historical effects of the learning process. The same thing will be strictly speaking true of any artificial minds as well, namely that it is a question of their physical construction and their history, but it makes more sense for us to think of “the particulars of the algorithm that we use to implement a prediction engine.”

In other words, if you really wanted to create a paperclip maximizer, you would have to be taking that goal into consideration throughout the entire process, including the process of programming a prediction engine. Of course, no one really knows how to do this with any goal at all, whether maximizing paperclips or some more human goal. The question we would have for Bostrom is then the following: Is there any reason to believe it would be easier to create a prediction engine that would maximize paperclips, rather than one that would pursue more human-like goals?

It might be true in some sense, “in principle,” as Bostrom says, that it would be easier to make the paperclip maximizer. But in practice it is quite likely that it will be easier to make one with human-like goals. It is highly unlikely, in fact pretty much impossible, that someone would program an artificial intelligence without any testing along the way. And when they are testing, whether or not they think about it, they are probably testing for human-like intelligence; in other words, if we are attempting to program a general prediction engine “without any goal,” there will in fact be goals implicitly inserted in the particulars of the implementation. And they are much more likely to be human-like ones than paperclip maximizing ones because we are checking for intelligence by checking whether the machine seems intelligent to us.

This optimistic projection could turn out to be wrong, but if it does, it is reasonably likely to turn out to be wrong in a way that still fails to confirm the orthogonality thesis in practice. For example, it might turn out that there is only one set of goals that is easily programmed, and that the set is neither human nor paperclip maximizing, nor easily defined by humans.

There are other possibilities as well, but the overall point is that we have little reason to believe that any arbitrary goal can be easily associated with intelligence, nor any particular reason to believe that “simple” goals can be more easily united to intelligence than more complex ones. In fact, there are additional reasons for doubting the claim about simple goals, which might be a topic of future discussion.

Some Complaints about Parts and Wholes

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In the comment here, John Nerst effectively rejects the existence of parts and wholes:

In my view, there must be a set of fundamental rules that the universe is running on and fundamental entities that doesn’t reduce to something else, and everything else is simply descriptions of the consequences of those rules. There is a difference between them, what we call it isn’t important. I don’t see how one could disagree with that without going into mystical-idealist territory.

The word “simply” in “simply descriptions of the consequences of those rules” has no plausible meaning except that wholes made out of fundamental particles, as distinct from the fundamental particles, do not exist: what really exists are the fundamental particles, and nothing more.

John denies that he means to reject the common sense idea that wholes exist by his statement:

I do mean different things by “humans exist” and “humans exist in the territory”, and you can’t really tell me what I mean against my saying so. I haven’t asserted that humans don’t exist (it depends on the meaning of “exist”).

But it is not my responsibility to give a plausible true meaning to his statements where I have already considered the matter as carefully as I could, and have found none; I do not see what his claim could mean which does not imply that humans do not exist, and I have explained why his claim would have this implication.

In a similar way, others reject the existence of parts. Thus Alexander Pruss remarks:

Parthood is a mysterious relation. It would really simplify our picture of the world if we could get rid of it.

There are two standard ways of doing this. The microscopic mereological nihilist says that only the fundamental “small” bits—particles, fields, etc.—exist, and that there are no complex objects like tables, trees and people that are made of such bits. (Though one could be a microscopic mereological nihilist dualist, and hold that people are simple souls.)

The macroscopic mereological nihilist says that big things like organisms do exist, but their commonly supposed constituents, such as particles, do not exist, except in a manner of speaking. We can talk as if there were electrons in us, but there are no electrons in us. The typical macroscopic mereological nihilist is a Thomist who talks of “virtual existence” of electrons in us.

Pruss basically agrees with the second position, which he expressed by saying at the end of the post, “But I still like macroscopic nihilism more than reductionism.” In other words, it is given that we have to get rid of parts and wholes; the best way to do that, according to Pruss, is to assert the existence of the things that we call wholes, and to deny the existence of the parts.

In effect, John Nerst says that there are no wholes, but there are fundamental things (such as particles) that have the power to act as if they were wholes (such as humans), even though such wholes do not actually exist, and Alexander Pruss says that there are no parts (such as particles), but there are simple unified things (such as humans) which have the power to act as if they had parts (such as particles), even though they do not actually have such parts.

To which we must respond: a pox on both your houses. In accord with common sense, both wholes and parts exist, and the difficulty of understanding the matter is a weakness of human reason, not a deficiency in reality.

The Self and Disembodied Predictive Processing

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While I criticized his claim overall, there is some truth in Scott Alexander’s remark that “the predictive processing model isn’t really a natural match for embodiment theory.” The theory of “embodiment” refers to the idea that a thing’s matter contributes in particular ways to its functioning; it cannot be explained by its form alone. As I said in the previous post, the human mind is certainly embodied in this sense. Nonetheless, the idea of predictive processing can suggest something somewhat disembodied. We can imagine the following picture of Andy Clark’s view:

Imagine the human mind as a person in an underground bunker. There is a bank of labelled computer screens on one wall, which portray incoming sensations. On another computer, the person analyzes the incoming data and records his predictions for what is to come, along with the equations or other things which represent his best guesses about the rules guiding incoming sensations.

As time goes on, his predictions are sometimes correct and sometimes incorrect, and so he refines his equations and his predictions to make them more accurate.

As in the previous post, we have here a “barren landscape.” The person in the bunker originally isn’t trying to control anything or to reach any particular outcome; he is just guessing what is going to appear on the screens. This idea also appears somewhat “disembodied”: what the mind is doing down in its bunker does not seem to have much to do with the body and the processes by which it is obtaining sensations.

At some point, however, the mind notices a particular difference between some of the incoming streams of sensation and the rest. The typical screen works like the one labelled “vision.” And there is a problem here. While the mind is pretty good at predicting what comes next there, things frequently come up which it did not predict. No matter how much it improves its rules and equations, it simply cannot entirely overcome this problem. The stream is just too unpredictable for that.

On the other hand, one stream labelled “proprioception” seems to work a bit differently. At any rate, extreme unpredicted events turn out to be much rarer. Additionally, the mind notices something particularly interesting: small differences to prediction do not seem to make much difference to accuracy. Or in other words, if it takes its best guess, then arbitrarily modifies it, as long as this is by a small amount, it will be just as accurate as its original guess would have been.

And thus if it modifies it repeatedly in this way, it can get any outcome it “wants.” Or in other words, the mind has learned that it is in control of one of the incoming streams, and not merely observing it.

This seems to suggest something particular. We do not have any innate knowledge that we are things in the world and that we can affect the world; this is something learned. In this sense, the idea of the self is one that we learn from experience, like the ideas of other things. I pointed out elsewhere that Descartes is mistaken to think the knowledge of thinking is primary. In a similar way, knowledge of self is not primary, but reflective.

Hellen Keller writes in The World I Live In (XI):

Before my teacher came to me, I did not know that I am. I lived in a world that was a no-world. I cannot hope to describe adequately that unconscious, yet conscious time of nothingness. I did not know that I knew aught, or that I lived or acted or desired. I had neither will nor intellect. I was carried along to objects and acts by a certain blind natural impetus. I had a mind which caused me to feel anger, satisfaction, desire. These two facts led those about me to suppose that I willed and thought. I can remember all this, not because I knew that it was so, but because I have tactual memory.

…

When I wanted anything I liked, ice cream, for instance, of which I was very fond, I had a delicious taste on my tongue (which, by the way, I never have now), and in my hand I felt the turning of the freezer. I made the sign, and my mother knew I wanted ice-cream. I “thought” and desired in my fingers.

…

Since I had no power of thought, I did not compare one mental state with another. So I was not conscious of any change or process going on in my brain when my teacher began to instruct me. I merely felt keen delight in obtaining more easily what I wanted by means of the finger motions she taught me. I thought only of objects, and only objects I wanted. It was the turning of the freezer on a larger scale. When I learned the meaning of “I” and “me” and found that I was something, I began to think. Then consciousness first existed for me.

Helen Keller’s experience is related to the idea of language as a kind of technology of thought. But the main point is that she is quite literally correct in saying that she did not know that she existed. This does not mean that she had the thought, “I do not exist,” but rather that she had no conscious thought about the self at all. Of course she speaks of feeling desire, but that is precisely as a feeling. Desire for ice cream is what is there (not “what I feel,” but “what is”) before the taste of ice cream arrives (not “before I taste ice cream.”)

 

Predictive Processing

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In a sort of curious coincidence, a few days after I published my last few posts, Scott Alexander posted a book review of Andy Clark’s book Surfing Uncertainty. A major theme of my posts was that in a certain sense, a decision consists in the expectation of performing the action decided upon. In a similar way, Andy Clark claims that the human brain does something very similar from moment to moment. Thus he begins chapter 4 of his book:

To surf the waves of sensory stimulation, predicting the present is simply not enough. Instead, we are built to engage the world. We are built to act in ways that are sensitive to the contingencies of the past, and that actively bring forth the futures that we need and desire. How does a guessing engine (a hierarchical prediction machine) turn prediction into accomplishment? The answer that we shall explore is: by predicting the shape of its own motor trajectories. In accounting for action, we thus move from predicting the rolling present to predicting the near-future, in the form of the not-yet-actual trajectories of our own limbs and bodies. These trajectories, predictive processing suggests, are specified by their distinctive sensory (especially proprioceptive) consequences. In ways that we are about to explore, predicting these (non-actual) sensory states actually serves to bring them about.

Such predictions act as self-fulfilling prophecies. Expecting the flow of sensation that would result were you to move your body so as to keep the surfboard in that rolling sweet spot results (if you happen to be an expert surfer) in that very flow, locating the surfboard right where you want it. Expert prediction of the world (here, the dynamic ever-changing waves) combines with expert prediction of the sensory flow that would, in that context, characterize the desired action, so as to bring that action about.

There is a great deal that could be said about the book, and about this theory, but for the moment I will content myself with remarking on one of Scott Alexander’s complaints about the book, and making one additional point. In his review, Scott remarks:

In particular, he’s obsessed with showing how “embodied” everything is all the time. This gets kind of awkward, since the predictive processing model isn’t really a natural match for embodiment theory, and describes a brain which is pretty embodied in some ways but not-so-embodied in others. If you want a hundred pages of apologia along the lines of “this may not look embodied, but if you squint you’ll see how super-duper embodied it really is!”, this is your book.

I did not find Clark obsessed with this, and I think it would be hard to reasonably describe any hundred pages in the book as devoted to this particular topic. This inclines to me to suggest that Scott may be irritated by such discussion of the topic that comes up because it does not seem relevant to him. I will therefore explain the relevance, namely in relation to a different difficulty which Scott discusses in another post:

There’s something more interesting in Section 7.10 of Surfing Uncertainty [actually 8.10], “Escape From The Darkened Room”. It asks: if the brain works to minimize prediction error, isn’t its best strategy to sit in a dark room and do nothing forever? After all, then it can predict its sense-data pretty much perfectly – it’ll always just stay “darkened room”.

Section 7.10 [8.10] gives a kind of hand-wave-y answer here, saying that of course organisms have some drives, and probably it makes sense for them to desire novelty and explore new options, and so on. Overall this isn’t too different from PCT’s idea of “intrinsic error”, and as long as we remember that it’s not really predicting anything in particular it seems like a fair response.

Clark’s response may be somewhat “hand-wave-y,” but I think the response might seem slightly more problematic to Scott than it actually is, precisely because he does not understand the idea of embodiment, and how it applies to this situation.

If we think about predictions on a general intellectual level, there is a good reason not to predict that you will not eat something soon. If you do predict this, you will turn out to be wrong, as is often discovered by would-be adopters of extreme fasts or diets. You will in fact eat something soon, regardless of what you think about this; so if you want the truth, you should believe that you will eat something soon.

The “darkened room” problem, however, is not about this general level. The argument is that if the brain is predicting its actions from moment to moment on a subconscious level, then if its main concern is getting accurate predictions, it could just predict an absence of action, and carry this out, and its predictions would be accurate. So why does this not happen? Clark gives his “hand-wave-y” answer:

Prediction-error-based neural processing is, we have seen, part of a potent recipe for multi-scale self-organization. Such multiscale self-organization does not occur in a vacuum. Instead, it operates only against the backdrop of an evolved organismic (neural and gross-bodily) form, and (as we will see in chapter 9) an equally transformative backdrop of slowly accumulated material structure and cultural practices: the socio-technological legacy of generation upon generation of human learning and experience.

To start to bring this larger picture into focus, the first point to notice is that explicit, fast timescale processes of prediction error minimization must answer to the needs and projects of evolved, embodied, and environmentally embedded agents. The very existence of such agents (see Friston, 2011b, 2012c) thus already implies a huge range of structurally implicit creature-specific ‘expectations’. Such creatures are built to seek mates, to avoid hunger and thirst, and to engage (even when not hungry and thirsty) in the kinds of sporadic environmental exploration that will help prepare them for unexpected environmental shifts, resource scarcities, new competitors, and so on. On a moment-by-moment basis, then, prediction error is minimized only against the backdrop of this complex set of creature-defining ‘expectations’.”

In one way, the answer here is a historical one. If you simply ask the abstract question, “would it minimize prediction error to predict doing nothing, and then to do nothing,” perhaps it would. But evolution could not bring such a creature into existence, while it was able to produce a creature that would predict that it would engage the world in various ways, and then would proceed to engage the world in those ways.

The objection, of course, would not be that the creature of the “darkened room” is possible. The objection would be that since such a creature is not possible, it must be wrong to describe the brain as minimizing prediction error. But notice that if you predict that you will not eat, and then you do not eat, you are no more right or wrong than if you predict that you will eat, and then you do eat. Either one is possible from the standpoint of prediction, but only one is possible from the standpoint of history.

This is where being “embodied” is relevant. The brain is not an abstract algorithm which has no content except to minimize prediction error; it is a physical object which works together in physical ways with the rest of the human body to carry out specifically human actions and to live a human life.

On the largest scale of evolutionary history, there were surely organisms that were nourished and reproduced long before there was anything analagous to a mind at work in those organisms. So when mind began to be, and took over some of this process, this could only happen in such a way that it would continue the work that was already there. A “predictive engine” could only begin to be by predicting that nourishment and reproduction would continue, since any attempt to do otherwise would necessarily result either in false predictions or in death.

This response is necessarily “hand-wave-y” in the sense that I (and presumably Clark) do not understand the precise physical implementation. But it is easy to see that it was historically necessary for things to happen this way, and it is an expression of “embodiment” in the sense that “minimize prediction error” is an abstract algorithm which does not and cannot exhaust everything which is there. The objection would be, “then there must be some other algorithm instead.” But this does not follow: no abstract algorithm will exhaust a physical object. Thus for example, animals will fall because they are heavy. Asking whether falling will satisfy some abstract algorithm is not relevant. In a similar way, animals had to be physically arranged in such a way that they would usually eat and reproduce.

I said I would make one additional point, although it may well be related to the above concern. In section 4.8 Clark notes that his account does not need to consider costs and benefits, at least directly:

But the story does not stop there. For the very same strategy here applies to the notion of desired consequences and rewards at all levels. Thus we read that ‘crucially, active inference does not invoke any “desired consequences”. It rests only on experience-dependent learning and inference: experience induces prior expectations, which guide perceptual inference and action’ (Friston, Mattout, & Kilner, 2011, p. 157). Apart from a certain efflorescence of corollary discharge, in the form of downward-flowing predictions, we here seem to confront something of a desert landscape: a world in which value functions, costs, reward signals, and perhaps even desires have been replaced by complex interacting expectations that inform perception and entrain action. But we could equally say (and I think this is the better way to express the point) that the functions of rewards and cost functions are now simply absorbed into a more complex generative model. They are implicit in our sensory (especially proprioceptive) expectations and they constrain behavior by prescribing their distinctive sensory implications.

The idea of the “desert landscape” seems to be that this account appears to do away with the idea of the good, and the idea of desire. The brain predicts what it is going to do, and those predictions cause it to do those things. This all seems purely intellectual: it seems that there is no purpose or goal or good involved.

The correct response to this, I think, is connected to what I have said elsewhere about desire and good. I noted there that we recognize our desires as desires for particular things by noticing that when we have certain feelings, we tend to do certain things. If we did not do those things, we would never conclude that those feelings are desires for doing those things. Note that someone could raise a similar objection here: if this is true, then are not desire and good mere words? We feel certain feelings, and do certain things, and that is all there is to be said. Where is good or purpose here?

The truth here is that good and being are convertible. The objection (to my definition and to Clark’s account) is not a reasonable objection at all: it would be a reasonable objection only if we expected good to be something different from being, in which case it would of course be nothing at all.