Not derived from Sense.—But is not this principle of causality derived from experience? We have already said that sense does not give it. I do not see with the eye the cause of the melting of the wax, much less does what I see contain the general principle, that every event must have a cause. Sense does not give me this.
Whether from Consciousness.—Still, may it not be a matter of experience in another way, given by consciousness, though not by sense. For example, I am conscious of certain volitions. These volitions are accompanied with certain muscular movements, and these, again, are followed by certain sensible effects upon surrounding objects. These changes produced on objects without are directly connected thus with my own mental states and changes, with the volitions of which I am directly conscious. Given, the volition on my part, with the corresponding muscular effort, and the external change is produced. I never observe it taking place without such preceding volition. I learn to regard my will as the cause, and the external change as the effect. I observe that it is in the power of others to produce changes in like manner. Thus I obtain the general idea of cause. It is given by consciousness and experience.
Notion of Causality not thus derived.—It is to this source that a very able and ingenious French philosopher would attribute our first idea of cause. I refer to Maine de Biran. I should agree with M. de Biran, that consciousness of our own voluntary efforts, and of the effects thus produced, may give us our first notion of cause. But it does not give us the law of causality. It extends to a given instance only, explains that, explains nothing further than that, cannot go beyond. I am conscious that in this given instance I have set in operation a train of antecedents and sequences which results in the given effect. I am not conscious that every event has, in like manner, a cause. My experience warrants no such assumption. No induction of facts and cases can possibly amount to this. Induction can multiply and generalize, but cannot stamp on that which is merely empirical and contingent, the character of universality and necessity. The law of causality, in a word, is to be distinguished from any given instance, or number of instances, of actually observed causation. The latter fall within the range of consciousness and experience, the former is given, if at all, as a law of the mind, a primary truth, an idea of reason.
Remarks of Professor Bowen.—As Professor Bowen has well observed, "The maxim, 'Every event must have a cause,' is not, like the so-called laws of nature, a mere induction founded on experience, and holding good only until an instance is discovered to the contrary; it is a necessary and immutable truth. It is not derived from observation of natural phenomena, but is super-imposed upon such observation by a necessity of the human intellect. It is not made known through the senses; and its falsity, under any circumstances, is not possible, is not even conceivable. The cause to which it points us, is not to be found in nature. The mere physicist, after vainly searching, ever since the world began, for a single instance of it, has, at length, abandoned the attempt as hopeless, and now confines himself to the mere description of natural phenomena. The true cause of these phenomena must be sought for in the realm, not of matter, but of mind."
What constitutes Cause.—In this last remark, the author quoted touches upon a question of no little moment. What constitutes a cause? We cannot here enter into the discussion of this question. It is sufficient to remark, that in the ordinary use of the word, as denoting that, but for which a given result will not be, many things beside mind are included as causes. A hammer, or some like instrument, is essential to the driving of a nail. The hammer may be called the cause of the nail being driven; the blow struck by means of the hammer may also be so designated. More properly, the arm which gave the blow, and, more correctly still, the mind which willed the movement of the arm, and not the consequent blow of the hammer, may be said to be the cause. If we seek for ultimate and efficient causes, we must, doubtless, come back to the realm of mind. It is mind that is, in every case, the first mover, the originator of any effect, and it may, therefore, be called the true and prime cause, the cause of causes.
History of the Doctrine.—Aristotle's View.—The history of the doctrine of causality presents a number of widely different theories, a brief outline of which is all that we can here give. The most ancient division and classification of causes is that of Aristotle, which is based on the following analysis: Every work brought to completion implies four things: an agent by whom it is done, an element or material of which it is wrought, a plan or idea according to which it is fashioned, and an end for which it is produced. Thus, to the production of a statue there must be a statuary, a block of marble, a plan in the mind of the artist, and a motive for the execution of the work. The first of these is termed the efficient cause, the second the material cause, the third the formal, and the fourth the final cause. This classification was universally adopted by the scholastic philosophers, and, to some extent, is still prevalent. We still speak of efficient and of final causes.
Locke's Derivation of Cause.—With regard to the origin of the idea of cause, there has been the greatest diversity of opinion. Locke derives it from sense; so do the philosophers of the sensationalist school. We perceive bodies modifying each other, and hence the notion of causality.
Theory of Hume and of Brown.—Hume denies the existence of what we call cause, or power of one object over another. He resolves it into succession or sequence of objects in regular order, and consequent association of them in our thoughts. Essentially the same is the theory of Brown, who resolves cause and effect into simple antecedence and sequence, beyond which we know nothing, and can affirm nothing.
Theory of Leibnitz.—The theory of Leibnitz verges upon the opposite extreme, and assigns the element of power or causal efficiency to every form of existence; every substance is a force, a cause, in itself.
Of Kant.—Kant and his school make cause a merely subjective notion, a law of the understanding, which it impresses upon outward things, a condition of our thought. We observe external phenomena, and, according to this law of our intelligence, are under the necessity of arranging them as cause and effect; but we do not know that, independent of our conception, there exists in reality any thing corresponding to this idea. The tendency of this theory, as well as that of Hume and Brown, to a thorough-going skepticism, is obvious at a glance. The theory of Maine de Biran has been already noticed.