To Mr. Simon Newcomb.

Cambridge, May 18, 1865.

. . . Much more thought and care than I have yet given to it would be necessary to a final and valuable decision on so important a matter as the invention of a nomenclature, — which is to ordinary metaphysics what the construction of a machine is to the working of it.

I have examined only one book at all likely to contain any terms suited to your purposes. A little work of Burgersdyck on Metaphysics contains innumerable scholastic subdivisions of the genus potentia, but none to the purpose; and I am inclined to believe that you are right in thinking that the ideas you propose for baptism have never before been analyzed, or at least signalized, with any distinctness. At any rate, such a conviction has been the more readily accepted by me, in that it saves me the trouble of continuing research in this direction.

I accordingly appealed to the classical knowledge of a friend for the proper Latin equivalents of the phrases “possibility for aught that we know” and “possibility for aught that we do not know,” or “for aught that exists;” and I had the good fortune to find that the Latin idiom is well adapted to these meanings, and renders them in phrases which have quite a scholastic ring. Quod, with the subjunctive, does the business.

Potentia quod sciamus and Potentia quod ne sciamus, or Potentia quod vere sit, express your P1 and P2 quite scholastically. For your P3 there is a choice of phrases, — Potentia quod velle possimus, or Potentia quod valeat voluntas, — which seem to me to hit the mark.

You do not, of course, wish that the nomenclature should decide whether P3 is included under either P1 or P2 as contradictory opposites, dividing, as they seem to do, the universe of potentiality between them; but you wish a term by which the problem can be stated and discussed without ambiguity or confusion; and these phrases seem to me to be sufficient for this purpose.

The sense of freedom or of liberty to choose, is the consciousness of a power to choose in a different way from that we actually follow, or of a possibility for aught that we can will, or for aught that the will avails. That is, the particular

act of the will does not represent all the determinants to action which we contemplate in deliberate choice.

Hence I propose for your

P1 . . . Potentia quod sciamus;

P2 . . . Potentia quod ne sciamus, vel quod vere sit;

P3 . . . Potentia quod velle possimus, vel quod valeat voluntas.

Potentiality is not contrasted in scholastic language with determination, but with actuality; existence in potentia with existence in actu or in esse. But it does not seem to me essential to adopt technical phrases for your C1, C2, C3, in so far as they are the negations of your P1, P2, P3, though it is obvious that a distinction should be made between actual causal determinations and the logical determinations of thought,—between what is determined without reference to our knowledge and what is determined in our knowledge.

Determination and indetermination seem to me to be the best terms, taken by themselves in their broadest sense, and excluding the use of the vague and ambiguous terms “possibility” and “potentiality.” And if we also exclude the words “liberty” and “necessity,” as Mr. Mill proposes, we shall simplify the problem of voluntary actions very materially.

The question will then be, whether there are any elements, known or unknown, which enter into volitional determinations not in accordance with the law of causation, or other than the regular consequents of conditions and determinations previously existing in our characters and circumstances.

I contend that no evidence of the existence of such elements can be distinguished from ignorance. All testimony in the matter must be negative. Dr. Johnson says: “We know our wills are free, and there’s an end on’t;” but I contend that we do not know that our wills are not free, and there isn’t even a beginning of a solution of the question from the testimony of consciousness. With reference to the possibility of any other evidence, the only practical problem is whether, in

considering human actions, we ought or ought not to presume that they fall under the law of causation, just as all other phenomena in nature are presumed to do. This problem is quite distinct from any anticipation we may have that we may become acquainted so intimately with the springs of human action as to be able to predict with certainty the course of an individual’s conduct. We do not hope to predict the weather with certainty, though this is probably a much simpler problem; but we nevertheless believe the complex phenomena of the weather to be made up of elementary regular sequences.

That our conscious volitions are not so compounded, we certainly can never know; and the only presumption in favor of this doctrine is its seeming dependence upon our sense of moral freedom and responsibility. But I contend that this seeming reason is only an illusion and a misunderstanding of the question. The world has been deceived for more than sixteen centuries by metaphors invented by some Alexandrian Platonists speculating on the nature of virtue. Sects, schisms, and strifes have been the consequents of these unfortunate metaphors drawn from Roman law. While everybody recognizes as real those feelings which we describe as a sense of moral freedom and the feeling of responsibility, few attend to the metaphorical character of the names which are given to them. “The virtuous man is free,” said the Platonic philosopher. “He is, like a Roman citizen, uncontrolled by a master.” “A vicious man is a slave.” Such is the metaphor: now what is the real character so described? This freedom is internal control in place of external control; centric or self control, which, so far from making a man free, in the scientific sense of the word, makes his life regular and his conduct calculable. He has a freedom like that of the solar system or like that of a normal growth. Again, moral responsibility was so named from legal responsibility in Roman law; and the sense of it is only the sense of dignity and trustworthiness

which is characteristic of moral feeling, a sense of being intrusted with interests not his own. This sense is also proportional to the virtue of a man, though it is not absent from any one capable of sympathetic and reflective action. Minus the metaphor, it has nothing to do with the question of philosophical liberty.

From all these considerations, I conclude that, if the terms in which the problem of philosophic liberty is discussed be freed from ambiguity and metaphor, there will be little or nothing left to discuss; only the idle question, in fact, whether in the world of the unknown, and the arcana of ignorance, there be not such things as undetermined beginnings, real, finite, first causes; — an idle question, because no affirmative testimony Can be adduced except our ignorance; and, as this is insufficient to disprove the law of causation in other cases, how can it be of weight in this?