Jacques Maritain Center : A First Glance at St. Thomas Aquinas / by Ralph McInerny


I have gone on at this length about Descartes because he conveniently represents the alternative to St. Thomas Aquinas. Not only that, he started something that continued to develop along the lines he had set down and ended by being something I am going to call Modernity.

By this I shall mean the big picture or view of the world that is opposed to the big picture or view of the world we find in Thomas Aquinas. Moreover, Modernity as I use the term here is incompatible with the faith. That is why the Church has put the stamp of her approval on Thomas.

When Leo XIII singled out Thomas, he had in mind a lot more than one man. I think he had in mind a tradition which reached its culmination in Thomas Aquinas. I am going to call that tradition the Classical view. It would be more accurate to call it the Aristotelian outlook, but I will use Classical to designate it, just as I call the opposed picture Modern rather than Cartesian. Probably no two terms have been more abused that classical and modern so they are tough enough to survive my use of them.

Aspects of Modernity

The Cartesian method arrives at the claim that the self is prior to the world, that our certainty of our own existence is greater than our certainty that the world exists. Indeed, we arrive at certainty of the existence of God and then derive from features of God the reliability of knowledge of the world.

The knowing subject first knows himself and then infers the existence of the world, of anything other than himself.

The notion that we already and first know many things for sure about the world is regarded as naïve and this has an important impact on what one takes philosophy to be and what learning it is like.

Philosophizing is said to begin with doubt. The philosophical life is pictured as casting a wary eye on ordinary claims to knowledge, cleansing our minds, making a blank slate of it in search of a starting point of thinking.

The first defensible thinking we do takes place after we have begun the study of philosophy. Whatever thinking you do prior to that is by definition suspect and has to be subjected to doubt if not outright skepticism.

This approach is not confined to Descartes. In fact, it becomes a common thread, with more and more of the features of things we know said to derive from our knowing, and less and less to belong to the thing itself.

Kant put his mark on the movement by, in effect, saying that we only know things as we know them. That sounds reasonable enough. But he takes this to mean that we do not know them as they are. Things themselves are never grasped by us, but exist out of reach, in some way involved in knowledge but never really known. What we know is what we know of things, not the things themselves.

Kant obviously thinks that knowing things as they are would be the same as knowing them as we don't know them.

The things themselves have become idle, and eventually are dropped all together, when Hegel simply identifies to be and to be thought.

In Modernity, the world is measured by us, not the other way around. Man has become the measure. This is humanism gone mad. This is what the Church seeks to counter by recommend the study of St. Thomas.

The Classical View

Modernity sees itself as a concerted effort to replace the Classical view which it regards as outmoded. Descartes was well aware that what he was proposing differed from the philosophy he had been taught in school. The philosophy he had been taught in school was, in his estimation, a jumble of assertions whose claim on our belief had never been seriously questioned.

So what by contrast with Modernity is the Classical view?

Everybody knows for sure things about the world, things whose existence cannot be coherently doubted.

The things of the world are what we first know, and we become aware of ourselves insofar as we know the world.

Before we know the world, our mind is a power, a potentiality, a possibility. Knowing our knowing first is simply not an option for us, since knowing in the first place is knowing something other than ourselves.

This has an impact on what we take philosophy to be.

Philosophy is not the study in which we for the first time come to know things for sure.

Philosophy presupposes that we are already in possession of truths about the world and ourselves. Indeed, if this were not so, the teacher would have nothing to address. Teaching is an effort to take us from what we already know to what we do not yet know.

Human thinking is measured by the world. Man as maker is the measure of what he makes, but the world itself is not an artifact of ours. Our knowledge of it is true insofar as it matches the way the world is.

Every human being who is no longer a child knows many truths about the world and himself and knows them for sure. They are beyond doubt.

Moreover, every human being knows moral truths, knows at least generally how a person should act and what actions are never permissible. The moral philosopher can help us get clear about what we already know, but he does not confer our primary moral knowledge on us. Again, he presupposes that we have it.

These features of what I am calling the Classical view are enough to contrast it with what I am calling Modernity.

These big pictures are clearly different. They are opposed to one another. If you accept the one, you reject the other, and vice versa.

Which One Is True?

So what? Why not say that some people are comfortable with the one picture, and others with the other, and that's about it?

If you choose the one picture you will, of course, think it is the true one, but so will a person who picks the opposite one. That means that from one viewpoint, the other will be regarded as false, and vice versa.

This may seem to underscore the arbitrariness of accepting the one picture or the other. Is the only way to appraise the one view to accept the other?

I want to suggest, first, that we are already recognizing at least one truth common to both views and, second, that this truth enables us to show that one of these views is unacceptable.

No matter which of these pictures you accept, you are rejecting the other. If Modernity is your cup of tea, you have dismissed the Classical view. If the Classical view is yours, you reject the Modern.

No surprise here, of course, since what is being accepted is the Principle of Contradiction, the rule of coherence.


The principle can be symbolized in that fashion. Let P stand for any truth claim, any proposition. The principle states that the proposition and its contradictory opposite cannot both be true.


Either a proposition or its contradictory is true. That this is rock bottom is clear from the one in which we sometimes say, "Look, either it is or it isn't."

When we reach the point of saying that, our backs are up against the wall. This is the final club in the bag. We use it when we want to reach beyond controversy to what anyone, even our opponent, will accept.

Little kids will chant back and forth, "It is." "It isn't," knowing it can't be both, no matter what it is.

If P is made to stand for Modernity, it will be agreed all around, by Modernist and Classicist alike, that P.v.-P.

Big deal? As it turns out, yes. If one of these views can be shown to violate intrinsically that principle, this will tell against it. I don't mean that any incoherence in either view discredits it. The incoherence has to be at the center, crucial, involved in a step without which none of the subsequent steps can be made.

Modernity is incoherent in this way. It has to rely on what it wants to reject in order to reject it.

What I have in mind is this. As the historical first step of the development of Modernity, in Descartes, the way in which doubt is cast on all judgments based on the senses is incoherent.

Descartes' senses sometimes deceive him. So do mine. From that fact, Descartes wants to conclude that he can never rely on the senses with the certainty he wants. That is, he can always what they report.

Let us consider a standard case of being deceived by our senses. The stick looks crooked in water. This can cause deception only if it is contrasted with a case where deception is excluded. Obviously it is presumed to be a straight stick which appears to be bent when seen in water.

It is when the stick is removed that we say, Good grief, it's straight. Because we say that, we take back what we said earlier about the crookedness of it when submerged.

Even to describe this simple case of deception, we have to take one of those judgments as certain. Unless we do, there is no contrast, no deception.

If you want to make a name for yourself as a philosopher, you could insist that the stick is really bent in its natural habitat, water, and only when plunged into air does it appear straight. But your theory will have to take as regulative the stick in water in order to speak of our being deceived by sticks in the open air.

Let us now make P stand for "judgments made on the basis of the senses." In order to claim that we must dismiss all such judgments as at least dubitable. Descartes must violate the Principle of Coherence. He must employ P.-P. He must trust his senses in order to doubt them, so he cannot universally doubt them.

That is why this small point is indeed a big deal. It stops Modernity before it can get going. Once it gets going, it proceeds with a kind of inevitability toward the loss of the world. The only world left is one "we" fashion in our heads. Man becomes the measure of all things, of what is that it is, of what is not that it is not. That was the claim both Plato and Aristotle showed to be nonsense. It is still nonsense. The classical view, and preeminently Thomism, is its antidote.

That much more, a great deal more, can and should be said of all these things is, of course, true. In this book we are just taking a peek inside philosophy. This judgment of Modernity does not alter after further and deeper discussion. However. If anything, it becomes more emphatically devastating.

Why Thomas?

It is because Thomas is the flower of the Classical view that the Church has singled him out in the special way she has. Whatever Thomas has to say of the world, ourselves, and what we ought to do, he will begin with what we already know. He will assume we already know a good many things for sure. That this certain knowledge is often confused and general is hardly surprising. It is nonetheless certain and more than good enough to provide the presupposed beginning points of philosophy.


Aristotle on the First Principle

There are some who, as we said, both themselves assert that it is possible for the same thing to be and not to be, and say that people can judge this to be the case. And among others many writers about nature use this language. But we have now posited that it is impossible for anything at the same time to be and not to be, and by this means have shown that this is the most indisputable of all principles. -- Some indeed demand that even this shall be demonstrated, but this they do through want of education, for not to know of what things one should demand demonstration, and of what one should not, argues want of education. For it is impossible that there should be demonstration of absolutely everything (there would be an infinite regress, so that there would still be no demonstration), but if there are things of which one should not demand demonstration, these persons could not say what principle they maintain to be more self-evident than the present one.

We can, however, demonstrate negatively even that this view is impossible, if our opponent will only say something; and if he says nothing, it is absurd to seek to give an account of our views to one who cannot give an account of anything, insofar as he cannot do so. For such a man, as such, is from the start no better than a vegetable. Now negative demonstration I distinguish from demonstration proper, because in a demonstration one might be thought to be begging the question, but if another person is responsible for the assumption we shall have a negative proof, no demonstration. The starting point for all such arguments is not the demand that our opponent shall say that something either is or is not (for this one might perhaps take to be a begging of the question), but that he shall say something which is significant both for himself, and for another, for this is necessary, if he really is to say anything. For, if he means nothing, such a man will not be capable of reasoning, either with himself or with another. But if any one grants this, demonstration will be possible, for we shall already have something definite. The person responsible for the proof, however, is not he who demonstrates but he who listens; for while disowning reason he listens to reason. And again he who admits this has admitted something is true apart from demonstrations, so that not everything will be 'so and not so.'

Let it be assumed then, as was said at the beginning, that the name has a meaning and has one meaning; it is impossible, then that 'being a man' should mean precisely 'not being a man', if 'man' not only signifies something about one subject but also has one significance (for we do not identify 'having one significance' with 'signifying something about one subject' since on that assumption even 'musical' and 'white' and 'man' would have one significance, so that all things would have been one; for they would all have had the same significance).

And it will not be possible to be and not to be the same thing, except in virtue of an ambiguity, just as if one whom we call 'man', others were to call 'not-man'; but the point in question is not this, whether the same thing can at the same time be and not be a man in name, but whether it can in fact.-Now if 'man' and 'not-man' mean nothing different, obviously 'not being a man' will mean nothing different from 'being a man'; so that 'being a man' will be 'not being a man' for they will be one. For being one means this -- being related as 'raiment' and 'dress' are, if their definition is one. And if 'being a man' and 'being a not-man' are to be one, they must mean one thing. But it was shown earlier that they mean different things.-Therefore, if it is true to say of anything that it is a man, it must be a two-footed animal (for this is what 'man' meant; and if this is necessary, it is impossible that the same thing should not at that time be a two-footed animal; for this is what 'being necessary' means -- that it is impossible for the thing not to be. It is, then, impossible that it should be at the same time true to say the same thing is a man and is not a man.

-- Metaphysics, Book 4, chapter 4

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