Atomic Theory

Revisiting Russell on Cause

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We discussed Bertrand Russell’s criticism of the first cause argument here. As I said there, he actually suggests, although without specifically making the claim, that there is no such thing as a cause, when he says:

That argument, I suppose, does not carry very much weight nowadays, because, in the first place, cause is not quite what it used to be. The philosophers and the men of science have got going on cause, and it has not anything like the vitality it used to have.

This is absurd, and it is especially objectionable that he employs this method of insinuation instead of attempting to make an argument. Nonetheless, let me attempt to argue on Russell’s behalf for a moment. It is perhaps not necessary for him to say that there is no such thing as a cause. Suppose he accepts my account of cause as an explanatory origin. Note that this is not purely an objective relationship existing in the world. It includes a specific relationship with our mind: we call something a cause when it is not only an origin, but it also explains something to us. The relatively “objective” relationship is simply that of origin.

A series of causes, since it is also a series of explanations, absolutely must have a first, since otherwise all explanatory force will be removed. But suppose Russell responds: it does not matter. Sure, this is how explanations work. But there is nothing to prevent the world from working differently. It may be that origins, namely the relationship on the objective side, do consist of infinite series. This might make it impossible to explain the world, but that would just be too bad, wouldn’t it? We already know that people have all sorts of desires for knowledge that cannot be satisfied. A complete account of the world is impossible in principle, and even in practice we can only obtain relatively local knowledge, leaving us ignorant of remote things. So you might feel a need of a first cause to make the world intelligible, Russell might say, but that is no proof at all that there is any series of origins with a first. For example, consider material causes. Large bodies are made of atoms, and atoms of smaller particles, namely electrons, protons, and neutrons. These smaller particles are made of yet smaller particles called quarks. There is no proof that this process does not go on forever. Indeed, the series would cease to explain anything if it did, but so what? Reality does not have to explain itself to you.

In response, consider the two following theories of water:

First theory: water is made of hydrogen and oxygen.

Second theory: every body of water has two parts, which we can call the first part and the second part. Each of the parts themselves has two parts, which we can call the first part of the first part, the second part of the first part, the first part of the second part, and the second part of the second part. This goes on ad infinitum.

Are these theories true? I presume the reader accepts the first theory. What about the second? We are probably inclined to say something like, “What does this mean, exactly?” But the very fact that the second theory is extremely vague means that we can probably come up with some interpretation that will make it true, depending in its details on the details of reality. Nonetheless, it is a clearly useless theory. And it is useless precisely because it cannot explain anything. There is no “causality” in the second theory, not even material causality. There is an infinite series of origins, but no explanation, and so no causes.

The first theory, on the other hand, is thought to be explanatory, and to provide material causes, because we implicitly suppose that we cannot go on forever in a similar way. It may be that hydrogen and oxygen are made up of other things: but we assume that this will not go on forever, at least with similar sorts of division.

But what if it does? It is true, in fact, that if it turns out that one can continue to break down particles into additional particles in a relatively similar manner ad infinitum, then “water is made of hydrogen and oxygen” will lose all explanatory force, and will not truly be a causal account, even in terms of material causes, even if the statement itself remains true. It would not follow, however, that causal accounts are impossible. It would simply follow that we chose the wrong account, just as one would be choosing wrongly if one attempted to explain water with the second theory above. The truth of the second theory is irrelevant; it is wrong as an explanation even if it is true.

As I have argued in a number of places, nature is not in the business of counting things. But it necessarily follows from this that it also does not call things finite or infinite; we are the ones who do that. So if you break down the world in such a way that origins are infinite, you will not be able to understand the world. That is not the world’s problem, but your problem. You can fix that by breaking down the world in such a way that origins are finite.

Perhaps Russell will continue to object. How do you know that there is any possible breakdown of the world which makes origins finite? But this objection implies the fully skeptical claim that nothing can be understood, or at least that it may turn out that nothing can be understood. As I have said elsewhere, this particular kind of skeptical claim implies a contradiction, since it implies that the same thing is known and unknown. This is the case even if you say “it might be that way,” since you must understand what you are saying when you say it might be that way.

Semi-Parmenidean Heresy

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In his book The Big Picture, Sean Carroll describes the view which he calls “poetic naturalism”:

As knowledge generally, and science in particular, have progressed over the centuries, our corresponding ontologies have evolved from quite rich to relatively sparse. To the ancients, it was reasonable to believe that there were all kinds of fundamentally different things in the world; in modern thought, we try to do more with less.

We would now say that Theseus’s ship is made of atoms, all of which are made of protons, neutrons, and electrons-exactly the same kinds of particles that make up every other ship, or for that matter make up you and me. There isn’t some primordial “shipness” of which Theseus’s is one particular example; there are simply arrangements of atoms, gradually changing over time.

That doesn’t mean we can’t talk about ships just because we understand that they are collections of atoms. It would be horrendously inconvenient if, anytime someone asked us a question about something happening in the world, we limited our allowable responses to a listing of a huge set of atoms and how they were arranged. If you listed about one atom per second, it would take more than a trillion times the current age of the universe to describe a ship like Theseus’s. Not really practical.

It just means that the notion of a ship is a derived category in our ontology, not a fundamental one. It is a useful way of talking about certain subsets of the basic stuff of the universe. We invent the concept of a ship because it is useful to us, not because it’s already there at the deepest level of reality. Is it the same ship after we’ve gradually replaced every plank? I don’t know. It’s up to us to decide. The very notion of “ship” is something we created for our own convenience.

That’s okay. The deepest level of reality is very important; but all the different ways we have of talking about that level are important too.

There is something essentially pre-Socratic about this thinking. When Carroll talks about “fundamentally different things,” he means things that differ according to their basic elements. But at the same kind the implication is that only things that differ in this way are “fundamentally” different in the sense of being truly or really different. But this is a quite different sense of “fundamental.”

I suggested in the linked post that even Thales might not really have believed that material causes alone sufficiently explained reality. Nonetheless, there was a focus on the material cause as being the truest explanation. We see the same focus here in Sean Carroll. When he says, “There isn’t some primordial shipness,” he is thinking of shipness as something that would have to be a material cause, if it existed.

Carroll proceeds to contrast his position with eliminativism:

One benefit of a rich ontology is that it’s easy to say what is “real”- every category describes something real. In a sparse ontology, that’s not so clear. Should we count only the underlying stuff of the world as real, and all the different ways we have of dividing it up and talking about it as merely illusions? That’s the most hard-core attitude we could take to reality, sometimes called eliminativism, since its adherents like nothing better than to go around eliminating this or that concept from our list of what is real. For an eliminativist, the question “Which Captian Kirk is the real one?” gets answered by, “Who cares? People are illusions. They’re just fictitious stories we tell about the one true world.”

I’m going to argue for a different view: our fundamental ontology, the best way we have of talking about the world at the deepest level, is extremely sparse. But many concepts that are part of non-fundamental ways we have of talking about the world- useful ideas describing higher-level, macroscopic reality- deserve to be called “real.”

The key word there is “useful.” There are certainly non-useful ways of talking about the world. In scientific contexts, we refer to such non-useful ways as “wrong” or “false.” A way of talking isn’t just a list of concepts; it will generally include a set of rules for using them, and relationships among them. Every scientific theory is a way of talking about the world, according to which we can say things like “There are things called planets, and something called the sun, all of which move through something called space, and planets do something called orbiting the sun, and those orbits describe a particular shape in space called an ellipse.” That’s basically Johannes Kepler’s theory of planetary motion, developed after Copernicus argued for the sun being at the center of the solar system but before Isaac Newton explained it all in terms of the force of gravity. Today, we would say that Kepler’s theory is fairly useful in certain circumstances, but it’s not as useful as Newton’s, which in turn isn’t as broadly useful as Einstein’s general theory of relativity.

…

A poetic naturalist will agree that both Captain Kirk and the Ship of Theseus are simply ways of talking about certain collections of atoms stretching through space and time. The difference is that an eliminativist will say “and therefore they are just illusions,” while the poetic naturalist says “but they are no less real for all of that.”

There are some good things about what Carroll is doing here. He is right of course to insist that the things of common experience are “real.” He is also right to see some relationship between saying that something is real and saying that talking about it is useful, but this is certainly worth additional consideration, and he does not really do it justice.

The problematic part is that, on account of his pre-Socratic tendencies, he is falling somewhat into the error of Parmenides. The error of Parmenides was to suppose that being can be, and can be thought and said, in only one way. Carroll, on account of confusing the various meanings of “fundamental,” supposes that being can be in only one way, namely as something elemental, but that it can be thought and said in many ways.

The problem with this, apart from the falsity of asserting that being can be in only one way, is that no metaphysical account is given whereby it would be reasonable to say that being can be thought and said in many ways, given that it can be in only one way. Carroll is trying to point in that direction by saying that our common speech is useful, so it must be about real things; but the eliminativist would respond, “Useful to whom? The things that you are saying this is useful for are illusions and do not exist. So even your supposed usefulness does not exist.” And Carroll will have no valid response, because he has already admitted to agreeing with the eliminativist on a metaphysical level.

The correct answer to this is the one given by Aristotle. Material causes do not sufficiently explain reality, but other causes are necessary as well. But this means that the eliminativist is mistaken on a metaphysical level, not merely in his way of speaking.

Mixing Water and Wine

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St. Thomas discusses what happens if you mix consecrated wine with another liquid:

I answer that, The truth of this question is evident from what has been said already. For it was said above (3; 5, ad 2) that the species remaining in this sacrament, as they acquire the manner of being of substance in virtue of the consecration, so likewise do they obtain the mode of acting and of being acted upon, so that they can do or receive whatever their substance could do or receive, were it there present. But it is evident that if the substance of wine were there present, then some other liquid could be mingled with it.

Nevertheless there would be a different effect of such mixing both according to the form and according to the quantity of the liquid. For if sufficient liquid were mixed so as to spread itself all through the wine, then the whole would be a mixed substance. Now what is made up of things mixed is neither of them, but each passes into a third resulting from both: hence it would result that the former wine would remain no longer. But if the liquid added were of another species, for instance, if water were mixed, the species of the wine would be dissolved, and there would be a liquid of another species. But if liquid of the same species were added, of instance, wine with wine, the same species would remain, but the wine would not be the same numerically, as the diversity of the accidents shows: for instance, if one wine were white and the other red.

But if the liquid added were of such minute quantity that it could not permeate the whole, the entire wine would not be mixed, but only part of it, which would not remain the same numerically owing to the blending of extraneous matter: still it would remain the same specifically, not only if a little liquid of the same species were mixed with it, but even if it were of another species, since a drop of water blended with much wine passes into the species of wine (De Gener. i).

Now it is evident that the body and blood of Christ abide in this sacrament so long as the species remain numerically the same, as stated above (4; 76, 6, ad 3); because it is this bread and this wine which is consecrated. Hence, if the liquid of any kind whatsoever added be so much in quantity as to permeate the whole of the consecrated wine, and be mixed with it throughout, the result would be something numerically distinct, and the blood of Christ will remain there no longer. But if the quantity of the liquid added be so slight as not to permeate throughout, but to reach only a part of the species, Christ’s blood will cease to be under that part of the consecrated wine, yet will remain under the rest.

Given the doctrine of transubstantiation, at least as St. Thomas understands it, so that it implies the existence of accidents without a subject, it is very difficult to understand how such a mixing would be possible at all. But his general position here is that a process analogous to substantial change necessarily happens if you mix anything into the consecrated wine, either according to a part of the wine, or according to the whole. He explains this kind of change in article five of the same question:

I answer that, Since “the corruption of one thing is the generation of another” (De Gener. i), something must be generated necessarily from the sacramental species if they be corrupted, as stated above (Article 4); for they are not corrupted in such a way that they disappear altogether, as if reduced to nothing; on the contrary, something sensible manifestly succeeds to them.

Nevertheless, it is difficult to see how anything can be generated from them. For it is quite evident that nothing is generated out of the body and blood of Christ which are truly there, because these are incorruptible. But if the substance, or even the matter, of the bread and wine were to remain in this sacrament, then, as some have maintained, it would be easy to account for this sensible object which succeeds to them. But that supposition is false, as was stated above (75, 2,4,8).

Hence it is that others have said that the things generated have not sprung from the sacramental species, but from the surrounding atmosphere. But this can be shown in many ways to be impossible. In the first place, because when a thing is generated from another, the latter at first appears changed and corrupted; whereas no alteration or corruption appeared previously in the adjacent atmosphere; hence the worms or ashes are not generated therefrom. Secondly, because the nature of the atmosphere is not such as to permit of such things being generated by such alterations. Thirdly, because it is possible for many consecrated hosts to be burned or putrefied; nor would it be possible for an earthen body, large enough to be generated from the atmosphere, unless a great and, in fact, exceedingly sensible condensation of the atmosphere took place. Fourthly, because the same thing can happen to the solid bodies surrounding them, such as iron or stone, which remain entire after the generation of the aforesaid things. Hence this opinion cannot stand, because it is opposed to what is manifest to our senses.

And therefore others have said that the substance of the bread and wine returns during the corruption of the species, and so from the returning substance of the bread and wine, ashes or worms or something of the kind are generated. But this explanation seems an impossible one. First of all, because if the substance of the bread and wine be converted into the body and blood of Christ, as was shown above (75, 2,4), the substance of the bread and wine cannot return, except the body and blood of Christ be again changed back into the substance of bread and wine, which is impossible: thus if air be turned into fire, the air cannot return without the fire being again changed into air. But if the substance of bread or wine be annihilated, it cannot return again, because what lapses into nothing does not return numerically the same. Unless perchance it be said that the said substance returns, because God creates anew another new substance to replace the first. Secondly, this seems to be impossible, because no time can be assigned when the substance of the bread returns. For, from what was said above (4; 76, 6, ad 3), it is evident that while the species of the bread and wine remain, there remain also the body and blood of Christ, which are not present together with the substance of the bread and wine in this sacrament, according to what was stated above (Question 75, Article 2). Hence the substance of the bread and wine cannot return while the sacramental species remain; nor, again, when these species pass away; because then the substance of the bread and wine would be without their proper accidents, which is impossible. Unless perchance it be said that in the last instant of the corruption of the species there returns (not, indeed, the substance of bread and wine, because it is in that very instant that they have the being of the substance generated from the species, but) the matter of the bread and wine; which, matter, properly speaking, would be more correctly described as created anew, than as returning. And in this sense the aforesaid position might be held.

However, since it does not seem reasonable to say that anything takes place miraculously in this sacrament, except in virtue of the consecration itself, which does not imply either creation or return of matter, it seems better to say that in the actual consecration it is miraculously bestowed on the dimensive quantity of the bread and wine to be the subject of subsequent forms. Now this is proper to matter; and therefore as a consequence everything which goes with matter is bestowed on dimensive quantity; and therefore everything which could be generated from the matter of bread or wine, if it were present, can be generated from the aforesaid dimensive quantity of the bread or wine, not, indeed, by a new miracle, but by virtue of the miracle which has already taken place.

This is rather strange, because he seems to be saying that the subsequent substantial forms inhere in quantity as in a subject, and that there is no matter there. But if this is possible in any way, and in particular if things remain in this state permanently, as he seems to suggest, then there seems to be little reason not to adopt Descartes’s view of material substance in general, and say that quantity is always the subject of substantial forms, rather than saying that some parts of the world have matter as a subject, and other parts quantity. The account might be more reasonable if he were to accept that when a new substance is generated, matter again comes to be, not by being “created anew,” but because the being of matter in general is from substantial form.

As we can see, this discussion is especially complex on account of the doctrine of transubstantiation and St. Thomas’s account of that doctrine. But if we simply consider the mixing of two liquids in general, various difficulties will remain. Suppose we have a glass of water and a glass of wine, and mix the two together. What exactly will happen?

It is manifest to the senses that when we do this, there is a period of time when parts of the resulting liquid are water, just as it was, and parts are wine, just as it was, without any mixture. But what about the surface where the two are in contact? What is happening there?

According to St. Thomas, there will be a quantitative part which shares in the qualities of each. And this is pretty reasonable. Just as we can see that part is wine and part is water, at a certain point we can see that part is watery wine. But how exactly did that watery part get that way? If it is a certain size, was there a sudden transition of a part which was water into the watery wine? Or the like with the wine becoming watery? Or was there a continuous process with an expanding mixed region? The last possibility seems most consistent with what we see, but it might be difficult to analyze this in terms of substantial change, as St. Thomas does, because such a continuous process would have no first moment when the mixed substance came to be. For if it did, it would come to be with a definite size, and thus the process would not be continuous, but would imply that some part suddenly went from not being watery wine to being watery wine.

Of course, it is one thing to say there are difficulties. It is quite another to say that they mean that the thing cannot happen. So none of this proves that the mixing of liquids is not a substantial change. Nonetheless, many of the ancient naturalists were moved by such considerations to adopt some form of atomic theory. If water and wine are each composed of atoms, the mixing process is easily understood — it is simply the movement in place of these atoms. Each part of the water remains as it was even qualitatively, and likewise each part of the wine, but the resulting mixture has different sensible qualities because one cannot distinguish the diverse qualities of each, just as mixing two very fine sands of different color may appear to result in a third color, even though the grains of sand are not changing qualitatively.

Modern atomic theory, of course, has far stronger arguments for it, but they are in principle, or at least were in the 18th and 19th centuries, of a very similar kind: atomic theory simply does a good job of explaining many of the things that we see happen in the world.

This is closely related to the discussion in the last post. When we construct a bicycle out of parts, it is manifest to the senses that the parts look just like they did before they were parts. And this is necessary, if it is true that those parts are governed by the same natural laws after they become parts that they were before they became parts. For however the parts “look,” they look this way because of how they act on the senses. So if their action does not change, the “way they look” will not change. Similarly, when we mix liquids, if the water parts and the wine parts do not change how they behave, the account one gives of the mixture must be an atomic theory or something very like it. That is, there must remain very small parts that act like water, and very small parts that act like wine. Or, given that wine and water are not in fact elements, at least the basic elemental parts must continue to act like those elemental parts.

Not All Things are Water

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The basic point of the post on Thales was that material things are composed of one or more material elements. The ancient materialists were accustomed not only to maintain this position, but also to assert that it also followed that there was nothing but those elements. Thus Democritus is said to have said,

By convention, sweet; by convention, bitter; by convention, hot; by convention,
cold; by convention, color; but in reality, atoms and void.

One could say that this is an example of the attitude of “this or nothing.” If everything is made of atoms, then either a thing is atoms, or it is nothing.

The correct answer here is not to say “this or that,” but “this and that,” that is, that things made of atoms are in some way atoms, but they are also things made of them, and the things made of them are not merely atoms.

 

All Things are Water

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In book I of his Metaphysics, Aristotle comments on earlier opinions about the first causes:

Evidently we have to acquire knowledge of the original causes (for we say we know each thing only when we think we recognize its first cause), and causes are spoken of in four senses. In one of these we mean the substance, i.e. the essence (for the ‘why’ is reducible finally to the definition, and the ultimate ‘why’ is a cause and principle); in another the matter or substratum, in a third the source of the change, and in a fourth the cause opposed to this, the purpose and the good (for this is the end of all generation and change). We have studied these causes sufficiently in our work on nature, but yet let us call to our aid those who have attacked the investigation of being and philosophized about reality before us. For obviously they too speak of certain principles and causes; to go over their views, then, will be of profit to the present inquiry, for we shall either find another kind of cause, or be more convinced of the correctness of those which we now maintain.

Of the first philosophers, then, most thought the principles which were of the nature of matter were the only principles of all things. That of which all things that are consist, the first from which they come to be, the last into which they are resolved (the substance remaining, but changing in its modifications), this they say is the element and this the principle of things, and therefore they think nothing is either generated or destroyed, since this sort of entity is always conserved, as we say Socrates neither comes to be absolutely when he comes to be beautiful or musical, nor ceases to be when loses these characteristics, because the substratum, Socrates himself remains. just so they say nothing else comes to be or ceases to be; for there must be some entity-either one or more than one-from which all other things come to be, it being conserved.

Yet they do not all agree as to the number and the nature of these principles. Thales, the founder of this type of philosophy, says the principle is water (for which reason he declared that the earth rests on water), getting the notion perhaps from seeing that the nutriment of all things is moist, and that heat itself is generated from the moist and kept alive by it (and that from which they come to be is a principle of all things). He got his notion from this fact, and from the fact that the seeds of all things have a moist nature, and that water is the origin of the nature of moist things.

Some think that even the ancients who lived long before the present generation, and first framed accounts of the gods, had a similar view of nature; for they made Ocean and Tethys the parents of creation, and described the oath of the gods as being by water, to which they give the name of Styx; for what is oldest is most honourable, and the most honourable thing is that by which one swears. It may perhaps be uncertain whether this opinion about nature is primitive and ancient, but Thales at any rate is said to have declared himself thus about the first cause.

It is possibly for polemical motives that Aristotle portrays Thales as asserting that water alone is the principle of all things, to the exclusion of other kinds of cause besides the material cause. That is, most materialists, ancient and modern, do not believe that matter is the sole principle of reality. They may think it is the most important principle, but they recognize that other principles are involved, much as Lucretius recognizes that his atoms alone are insufficient to explain the world, but he must add something:

We wish thee also well aware of this:
The atoms, as their own weight bears them down
Plumb through the void, at scarce determined times,
In scarce determined places, from their course
Decline a little- call it, so to speak,
Mere changed trend. For were it not their wont
Thuswise to swerve, down would they fall, each one,
Like drops of rain, through the unbottomed void;
And then collisions ne’er could be nor blows
Among the primal elements; and thus
Nature would never have created aught.

We can understand however that even if Aristotle’s account may not be a completely accurate account of Thales’s opinions, Aristotle likely has a charitable motive for his presentation, namely the education of the reader, as by beginning by discussing the position that matter alone is the first cause, it becomes easier to see the necessity of other principles. And it is also possible that Thales did not mention any other principles simply because his interest was in the material principle, rather than from the wish to deny other principles.

There is some probability to the opinion, mentioned by Aristotle, that Thales’s idea about water had ancient predecessors. For example, there may be something like this in Genesis 1:

In the beginning when God created the heavens and the earth, the earth was a formless void and darkness covered the face of the deep, while a wind from God swept over the face of the waters. Then God said, “Let there be light”; and there was light. And God saw that the light was good; and God separated the light from the darkness. God called the light Day, and the darkness he called Night. And there was evening and there was morning, the first day.

And God said, “Let there be a dome in the midst of the waters, and let it separate the waters from the waters.” So God made the dome and separated the waters that were under the dome from the waters that were above the dome. And it was so. God called the dome Sky. And there was evening and there was morning, the second day.

And God said, “Let the waters under the sky be gathered together into one place, and let the dry land appear.” And it was so. God called the dry land Earth, and the waters that were gathered together he called Seas. And God saw that it was good.

The text speaks of a number of principles, including God, and formless matter. But the formless matter is virtually identified with water; even when the earth is a “formless void,” there is still a “deep”, and there is still a “face of the waters.” And God makes the world by divisions in the waters, creating first sky and world, and then creating dry land by limiting the lower waters.

We can ask whether Thales was right in several different ways:

First, was he right if he is understood as Aristotle understands him? In this way, his position would involve denying all principles other than material principles. And in this way Thales was wrong, since there are other principles.

Second, was he right if he is understood in contrast with other materialist philosophers such as Anaximenes, who said that all things are made of air? We can see that there is a certain difficulty in such a supposition from the beginning. For if there is only one material principle of all things, why call it “water” or “air” in particular? If water contains nothing but the first material principle, and air contains nothing but the first material principle, why is one of them identified with the principle rather than the other?

Nonetheless, we can understand the claim to be something like, “Water is the most basic and natural form of the first material principle.” In this case, what it means to be the most basic and natural would be a matter of investigation, but there is nothing impossible about it in principle. But if we understand it in this way, Thales’s position (along with that of Anaximenes and others) is refuted by modern science, since water is known to be made of other more basic things, namely oxygen and hydrogen.

But we can ask whether Thales and Anaximenes were both right in a third way, a more generic way. If we break composite material things down into their parts, and their parts into their parts, and so on, will we always arrive at one basic material “stuff” which all other things are made out of?

This would necessarily be different from the prime matter of Aristotle, because this matter is understood to be completely formless. So while it may be part of a substance along with substantial form, it is not a part in the way that an arm is a part of a human being, or in the way that oxygen is part of water. A part in the latter sense already has some actuality; an arm has a certain shape even apart from being a part of a human being, and oxygen has qualities that it has even apart from water, while prime matter has no actuality whatsoever.

Since every order of causes comes to a first cause, the same will be true if we follow the order of material causality found by asking, “What parts is this made out of?” This cannot be refuted even if it turns out that material things are infinitely divisible, because it will not actually be true that anything is made out of an infinite number of parts. If we say, “this is made out of two halves, and the halves out of more halves, and so on,” this is not an explanation at all, as was pointed out in the post linked above, and so it cannot be a true account of why the thing is as it is. It may be that the thing is potentially divisible in those ways; but it is not actually made out of those parts. Instead, we are asking what we will arrive at if we look at the material composition of things, looking only for things with some actuality, and stopping when we find something which is not made up of other things in this way.

We made a strong argument that there only one first efficient cause. But we cannot duplicate that argument to show that there must be only one first material part of things, since the first efficient cause could be an adequate explanation of two or more first material causes. The theory of the four (or five) elements is an explanation like this. The first material parts are thought be four or five, according to this account, and in this way Thales would have been mistaken.

We can see some motivation for holding such a position. If there is fundamentally only one kind of “stuff,” why do we see various things in the world, such as plants and animals, rocks, chairs, and people? An account with a number elements can say that they form various things by being combined in various proportions and ways, while it is not evident how this question can be answered, if there is only one element.

Nonetheless, this does not really refute the position that there is fundamentally a single material element. If that element can exist in various ways, then it would be possible to explain how it could be used to form more complex substances. It is true that this would still leave something to be explained, namely the nature of those various ways that the element can exist, and how and why they come to be.

The position is neither refuted nor established by modern science. The Standard Model of particle physics contains many elementary particles, but in any case it is not thought to be a complete theory of physics.

Considerations of simplicity would favor the position of Thales. Other things being equal, it should be thought that a theory with a single element is more likely than one with ten elements; one with ten more likely than one with a hundred, and so on. Nonetheless, there does not seem to be any proof of Thales’s general position, nor any refutation of it. But one way or another, there will be one or more simplest material parts that everything else is made out of.