Possibility

Counterfactuals as Historical Fiction

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Suppose someone reading Anne of Green Gables asks a question about what happened before the story begins. For example, what did Anne have for lunch 37 days before her arrival in Avonlea?

It is easy to see that this question does not have one true answer. There is no such thing as what she really had for lunch, because it is a story, and that meal is not included in it. On the other hand, despite the lack of any absolute truth here, some answers remain more reasonable than others. For example, “She had salad,” is a more sensible answer than “she ate crushed glass that day.” Just as I said in regard to “why” something is the case, one can give a partial answer, in the sense of showing that some options are more intelligible than others, without being able to exclude some options entirely.

These same things will apply to questions about a work of historical fiction, although the intended historical context will provide additional ways to show that some answers are more sensible than others. Thus if a story is set in ancient Rome, the claim that someone had corn for lunch is unreasonable due to the historical context, although not as unreasonable as some other possibilities that you could suggest.

Now consider a counterfactual question about your current situation: “What would you do if it were 120 degrees Fahrenheit in your house?”

There is no fundamental difference between this and the case of historical fiction. In effect, we just created a story about you: “It was 120 degrees in your house. You…”

Like the case of historical fiction, some answers will be more sensible than others, but there is no thing that you really would do in that situation. The story didn’t really take place, but if it did, it would have taken place with a lot more concrete detail, and that concrete detail could determine the specific answer to the question. If Anne of Green Gables were a true story, her concrete situation would have determined what she had for lunch that day. And if it were really 120 degrees in your house, what you would do would depend on how and why things got that way, as well as other factors in your concrete situation.

Some philosophers have spent a lot of time on this kind of counterfactual question, apparently largely from a desire for absolute answers. For example, some suggest that a counterfactual is true if the claim is true in the nearest possible world where the antecedent is true. In a similar way, Molinists argue that in order to be omniscient, God has to know what you would do if it were 120 degrees in your house, and that it must be one specific thing, so that there is one thing that you really would do in that situation. They call this kind of knowledge “middle” knowledge, namely something in between knowledge of what actually is and knowledge of what merely might have been.

All accounts of this kind are wasted effort. The brief account above is sufficient.

Necessity, Possibility, and Impossibility

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I spoke here about various kinds of necessity, but did not explain the nature of necessity in general. And in the recent post on Hume’s idea of causality, it was not necessary to explain the nature of necessity, because the actual idea of causality does not include necessity. Thus for example a ball can break a window even if it would have been possible for someone to catch the ball, but the person did not do so.

Sometimes it is asked whether necessity implies possibility: if it is necessary that Tuesday follow Monday, it is possible for Tuesday to follow Monday? I am inclined (and I think most are inclined) to say yes, on the grounds that to say that something is not possible is normally understood to imply that the thing is impossible; thus if it is not possible for Tuesday to follow Monday, it is impossible. But this is largely a verbal question: regardless of how we answer this, the real point is that the necessary is the same kind of thing as the possible, except that possibilities are many while the necessary is one. And likewise, a count of zero for the same things implies impossibility. Thus there is something that we are counting: if we find none of them, we speak of an impossibility. If we find only one, we speak of one necessity. And if we find many, we speak of many possibilities.

What are we counting here? Let’s take an example. Horses can be white, or red, or brown, among other possibilities. So there are many possible colors for a horse. And on the other hand snow is always white (or so let us pretend.) So there is only one possible color for snow, and so snow is “necessarily” white. Meanwhile, air is always colorless (or so let us pretend.) So it is impossible for air to have a color. Based on this example, we propose that what we are counting is the number of forms that are suitable for a given matter. Someone might object that if we analyze the word “suitable” here it might involve some sort of circularity. This may well be the case; this is a common occurrence, as with desire and the good, and with virtue and happiness. Nonetheless, I think we will find it worthwhile to work with this definition, just as in those earlier cases.

 

Whatever Can Happen Sometimes Does

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In St. Thomas’s third way, he says, “that which is possible not to be at some time is not.” Basically he is saying that if something is possible, it will be actual sooner or later. Is this really the case?

With some qualifications, it is indeed the case. If the probability of something during equal units of time remains fixed, or if it does not decrease sufficiently quickly, then at the limit of infinite time, the probability that the thing will happen sooner or later will converge to one. Thus, to give an arbitrary example, if there is a chance that human beings will produce a space elevator during the next 20 years, and the chance for each period of 20 years is not constantly decreasing, then it will happen sooner or later.

Of course the qualifications imply that there are still plenty of ways that this could fail to happen, as if time does not go on forever, or if something happens (e.g. the kind of thing that might be called “the end of the world”) that reduces this chance to zero, or that causes it to start going down, and to continue going down forever, quickly enough that the total probability converges to something less than one.

It might be possible to argue against St. Thomas’s application of this principle in the third way, since even if we believe that it could have happened that nothing existed, we might reasonably suppose that once something exists, the probability of “nothing exists” being true in the future is immediately reduced to zero. Nonetheless, it is certainly true that the existence of contingent beings implies the existence of a necessary being.