A History of Mediaeval Jewish Philosophy

by Isaac Husik

In Greek philosophy for the first time we find speculations concerning the common element or elements out of which the world is made—the material cause as Aristotle later called it. The Sophists and Socrates gave the first impulse to a logical analysis of what is involved in description or definition. The concept as denoting the essence of a thing is the important contribution Socrates made to knowledge. Plato objectified the concept, or rather he posited an object as the basis of the concept, and raised it out of this world of shadows to an intelligible world of realities on which the world of particulars depends. But it was Aristotle who made a thoroughgoing analysis of thing as well as thought, and he was the master of knowledge through the middle ages alike for Jew, Christian and Mohammedan.

First of all he classified all objects of our experience and found that they can be grouped in ten classes or categories as he called them. Think of any thing you please and you will find that it is either an object in the strict sense, i. e., some thing that exists independently of anything else, and is the recipient of qualities, as for example a man, a mountain, a chair. Or it is a quantity, like four, or cubit; or a quality, like good, black, straight; or a relation like long, double, master, slave; and so on throughout the ten categories. This classification applies to words and thoughts as well as to things. As an analysis of the first two it led him to more important investigations of speech and thinking and arguing, and resulted in his system of logic, which is the most momentous discovery of a single mind recorded in history. As applied to things it was followed by a more fundamental analysis of all real objects in our world into the two elements of matter and form. He argued as follows: nothing in the material world is permanent as an individual thing. It changes its state from moment to moment and finally ceases to be the thing it was. An acorn passes a number of stages before it is ripe, and when it is placed in the ground it again changes its form continually and then comes out as an oak. In artificial products man in a measure imitates nature. He takes a block of marble and makes a statue out of it. He forms a log into a bed. So an ignorant man becomes civilized and learned. All these examples illustrate change. What then is change? Is there any similarity in all the cases cited? Can we express the process of change in a formula which will apply to all instances of change? If so, we shall have gained an insight into a process of nature which is all-embracing and universal in our experience. Yes, we can, says Aristotle. Change is a play of two elements in the changing thing. When a thing affected with one quality changes into a thing with the opposite quality, there must be the thing itself without either of the opposite qualities, which is changing. Thus when a white fence becomes black, the fence itself or that which undergoes the change is something neither white nor black. It is the uncolored matter which first had the form of white and now lost that and took on the form of black. This is typical of all change. There is in all change ultimately an unchanging substratum always the same, which takes on one quality after another, or as Aristotle would say, one form after another. This substratum is matter, which in its purity is not affected with any quality or form, of which it is the seat and residence. The forms on the other hand come and go. Form does not change any more than matter. The changing thing is the composite of matter and form, and change means separation of the actual components of which one, the form, disappears and makes room for its opposite. In a given case, say, when a statue is made out of a block of marble, the matter is the marble which lost its original form and assumed the form of a statue. In this case the marble, if you take away both the previous form and the present, will still have some form if it is still marble, for marble must have certain qualities if it is to be marble. In that case then the matter underlying the change in question is not pure matter, it is already endowed with some primitive form and is composite. But marble is ultimately reducible to the four elements, fire, air, water, earth, which are simpler; and theoretically, though not in practice, we can think away all form, and we have left only that which takes forms but is itself not any form. This is matter.

Here the reader will ask, what kind of thing is it that has no form whatsoever, is it not nothing at all? How can anything exist without being a particular kind of thing, and the moment it is that it is no longer pure matter. Aristotle's answer is that it is true that pure matter is never found as an objective existence. Point to any real object and it is composed of matter and form. And yet it is not true that matter is a pure figment of the imagination; it has an existence of its own, a potential existence. And this leads us to another important conception in the Aristotelian philosophy.

Potentiality and actuality are correlative terms corresponding to matter and form. Matter is the potential, form is the actual. Whatever potentialities an object has it owes to its matter. Its actual essence is due to its form. A thing free from matter would be all that it is at once. It would not be liable to change of any kind, whether progress or retrogression. All the objects of our experience in the sublunar world are not of this kind. They realize themselves gradually, and are never at any given moment all that they are capable of becoming. This is due to their matter. On the other hand, pure matter is actually nothing. It is just capacity for being anything, and the moment it is anything it is affected with form.

It is clear from this account that matter and form are the bases of sublunar life and existence. No change, no motion without matter and form. For motion is presupposed in all kinds of change. If then all processes of life and death and change of all kinds presuppose matter and form, the latter cannot themselves be liable to genesis and decay and change, for that would mean that matter is composed of matter and form, which is absurd. We thus see how Aristotle is led to believe in the eternity of matter and motion, in other words, the eternity of the world processes as we know them.

Motion is the realization of the potential qua potential. This is an Aristotelian definition and applies not merely to motion in the strict sense, i. e., movement in place, or motion of translation, but embraces all kinds of change. Take as an example the warming of the air in a cold room. The process of heating the room is a kind of motion; the air passes from a state of being cold to a state of being warm. In its original state as cold it is potentially warm, i. e., it is actually not warm, but has the capacity of becoming warm. At the end of the process it is actually warm. Hence the process itself is the actualization of the potential. That which is potential cannot make itself actual, for to make itself actual it must be actual, which is contrary to the hypothesis of its being potential. Potentiality and actuality are contradictory states and cannot exist side by side in the same thing at the same time in the same relation. There must therefore be an external agent, itself actual, to actualize a potential. Thus, in the above illustration, a cold room cannot make itself warm. There must be some agency itself actually warm to cause the air in the room to pass from cold to warm. This is true also of motion in place, that a thing cannot move itself and must be moved by something else. But that something else if itself in motion must again be moved by something else. This process would lead us to infinity. In order that a given thing shall be in motion, it would be necessary for an infinite number of things to be in motion. This is impossible, because there cannot be an infinite number of things all here and now. It is a contradiction in terms. Hence if anything is to move at all, there must be at the end of the finite chain a link which while causing the next link to move, is itself unmoved. Hence the motion existing in the world must be due ultimately to the existence of an unmoved mover. If this being causes motion without being itself in motion it does not act upon the bodies it moves as one body acts upon another, for a body can move another body only by being itself in motion. The manner in which the unmoved mover moves the world is rather to be conceived on the analogy of a loved object moving the loving object without itself being moved. The person in love strives to approach and unite with the object of his love without the latter necessarily being moved in turn. This is the way in which Aristotle conceives of the cause of the world's motion. There is no room here for the creation of the world. Matter is eternal, motion is eternal, and there is an eternal mind for the love of which all motions have been going on, eternally.

The unmoved mover, or God, is thus not body, for no body can move another body without being itself in motion at the same time. Besides, all body is finite, i. e., it has a finite magnitude. A body of infinite magnitude is an impossibility, as the very essence of body is that it must be bounded by surfaces. A finite body cannot have an infinite power, as Aristotle proves, though we need not at present go into the details of his proof. But a being which causes eternal motion in the world must have an infinite power to do this. Hence another proof that God is not corporeal.

If God is not subject to motion, he is not subject to change of any kind, for change involves motion. As matter is at the basis of all change God is without matter, hence he is pure form, i. e., pure actuality without the least potentiality. This means that he is what he is wholly all the time; he has no capacities of being what he is at any time not. But if he is not corporeal, the nature of his actuality or activity must be Thought, pure thinking. And the content of his thought cannot vary from topic to topic, for this would be change, which is foreign to him. He must be eternally thinking the same thought; and the highest thought it must be. But the highest thought is himself; hence God is pure thought thinking himself, thought thinking thought.

The universe is in the shape of a sphere with the earth stationary in the centre and the heavens revolving around it exactly as appears to us. The element earth is the heaviest, hence its place is below or, which is the same thing, in the centre. This is its natural place; and its natural motion when away from the centre is in a straight line toward the centre. Water is the next heaviest element and its natural place is just above earth; hence the water in the world occupies a position spherical in shape round about the earth, i. e., it forms a hollow sphere concentric with the earth. Next comes the hollow sphere of air concentric with the other two. Its natural motion when away from its place in the direction of the earth is in a straight line toward the circumference of the world, not however going beyond the sphere of the lightest element of all, namely, fire. This has its natural place outside of the other elements, also in the form of a hollow sphere concentric with the other three. Its natural motion is in a straight line away from the centre of the world and in the direction of the circumference. Our earth, water, air and fire are not really the elements in their purity. Each one has in it also mixtures of the other three elements, the one which gives it the name predominating.

All minerals, plants and animals are formed from these four elements by various combinations, all together forming the sublunar world, or the world of generation and decay. No individual thing in this world is permanent. All are subject to change and to ultimate destruction, though the destruction of one thing is the genesis of another. There is no annihilation.