Writings of Charles S. Peirce: A Chronological Edition, Volume 2. Charles S. Peirce

is important to observe that the essential difference between a reality and a nonreality, is that the former has an existence entirely independent of what you or I or any number of men may think about it. What I dream, for example, only exists so far as my dreaming imagination creates it. But the fact that I have had such a dream, remains true whether I ever reflect upon that fact or not. The dream, therefore, as a mental phenomenon, is a reality; but the thing dreamed is a figment. If there ever really was such a man as Romulus, he would have existed just the same if history had never mentioned him; but if he is not a reality he exists only in the fables which have been told of the foundation of Rome. When Gray says,

      Full many a gem of purest ray serene

      The dark unfathomed caves of ocean bear;

      Full many a flower is born to blush unseen

      And waste its sweetness on the desert air;

      he expresses with precision the essential character of reality. But when we say that the real is that which is independent of how you or I or any number of men think about it, we have still left the conception of independent being to be analyzed. Before making that analysis we must consider the conceptions of one, two, and three.

      We have seen that an ens is something to which the copula is can be applied. But is is a word whose meaning is not complete in itself. It means nothing to say that anything is (in the sense of the copula) unless I say what it is; for the only function of the copula is to join subject and predicate. Hence, whatever is, is somehow. This somehow of entity I propose to express by the term quality. A quality therefore in the very general sense in which I shall use it, denotes whatever can be expressed by all that comes after is in a complete assertion. Every ens, then, has some quality for to say that it is an ens is to say that it may be made the subject of an assertion and that assertion must have some predicate. There is no conception so vague that some thing cannot be asserted of the object of it, for it is the first condition of thought that some quality must be thought in the thought.

      Specimen of a Dictionary of the Terms of Logic and allied Sciences: A to ABS

       MS 145: November 1867

      This is not supposed to be complete, but only as illustrating the state of my materials, Nov. 1867.

      Dictionary A-ABS

      A

      The first letter of the alphabet is used as a sign in logic.

      1. In Aristotle’s Analytics, A denotes the major extreme of a syllogism of the first figure. He very seldom employs it otherwise.

      2. Since the middle of the thirteenth century, it has been usually employed to denote a universal affirmative proposition. E, I, and O, denote the other forms of categoricals, according to the verse,

      Asserit A, negat E, sunt universaliter ambae;

      Asserit I, negat O, sunt particulariter ambae.

      It is doubtful whether this use of the vowels originated in the East or in the West. Prantl shows that it had been usual to represent the four forms of propositions by writing simply, and and he supposes that the A, E, and I, are the accented vowels of the first three words and that the O represents the OY of Hamilton thinks that the four vowels are the first two of the words affirmo and nego. The opinion of the last writer that they were invented by Petrus Hispanus can in any case hardly be sustained.

      3. A has been used in several other senses which it is unnecessary to specify.

      A

      A parte ante. In reference to the past.

      See Universal.

      A parte post. In reference to the future.

      See Universal.

      A posse. See Consequence.

      A posteriori. Explained under A priori.

      A potiori. See Denomination.

      A priori. This term and a posteriori are said to be directly derived from the use by Aristotle of prior and posterior, . I do not, however, know of the occurrence of these expressions in any writer previous to Cajetan, though per priora is found (Aquinas, Summa, Prim, prim., quaest. 2, art. 2) in the same sense. The well-authorized senses of these terms are as follows.

      1. “Previously to Kant, the terms a priori and a posteriori were, in a sense which descended from Aristotle, properly and usually employed,—the former to denote a reasoning from cause to effect—the latter, a reasoning from effect to cause.” Hamilton, Reid’s Works, p. 762. See also Trendelenburg, Elementa Logices Aristoteleae, §19.

      2. By Baumgarten and the Wolffians, a priori demonstration was confounded with synthetical demonstration, and a posteriori demonstration with analytical demonstration. The terms had previously been used in this way by Le Clerc and others. See Hollmann, Part 3, cap. 3, §517.

      3. Finally, there is the metaphysical sense of the terms, now universal, and introduced by Kant. There are some traces of this use before him, as in the two quotations which follow.

      “Sense apprehends individual bodies without, by something derived from them, and so a posteriori, the senses being last are the images of things. The sensible ideas of things are but umbratile and evanid images of the sensible things, like shadows projected from them; but knowledge is a comprehension of a thing proleptically, and as it were a priori.” Cudworth, Eternal and Immutable Morality, Ch. 3, §5, p. 99.

      “It is easy to see that these two concepts must be taken relatively. For if we should make not only immediate experiences but also all that we can discover by means of them a posteriori, then the concept a priori could only be used in a few of those cases in which we predetermine something by arguments, since in such case we must in no degree depend on any of the premises of experience. And so there would be scarcely anything at all in our cognition which was a priori.” Lambert, Book 1, ch. 9, §637, vol. 1, p. 413.

      The following passages show Kant’s use of the terms. “The rules of logic can therefore be regarded as a priori, that is, independent of all experience, since they contain merely the conditions of the use of the understanding in general, without distinction of objects.” Logik, Einleitung I. “Although all our cognition begins with experience, it does not necessarily on that account arise out of experience. For it might easily be that even our experiential cognition was a compound of that which we receive by impressions and of that which our cognitive faculties (only stimulated by sensuous impressions) bring forth from themselves. … Is there such a cognition independent of experience and even of all impressions of sense? One terms such cognitions a priori, and distinguishes them from the empirical, which have their sources a posteriori. “ Kritik d. reinen Vernunft, 2nd Ed., Einleitung I.

      A priori employment of a synthesis. Its employment in reference to representations which are not empirical. Kant, Kritik, p. 99.

      A priori knowledge “embraces those principles which, as the conditions of the exercise of the