PROPOSITIONS. 67 



exists. This, however, only shows that there is an ambiguity in the word 

 is ; a word which not only performs the function of the copula in affirma- 

 tions, but has also a meaning of its own, in virtue of which it may itself be 

 made the predicate of a proposition. That the employment of it as a cop- 

 ula does not necessarily include the affirmation of existence, appears from 

 such a proposition as this, A centaur is a fiction of the poets ; where it can 

 not possibly be imphed that a centaur exists, since the proposition itself ex- 

 pressly asserts that the thing has no real existence. 



Many volumes might be filled with the frivolous speculations concerning 

 the nature of Being {to 6v, ovala, Ens, Entitas, Essentia, and the like), which 

 have arisen from overlooking this double meaning of the word to be; from 

 supposing that Avhen it signifies to exist, and when it signifies to be some 

 specified thing, as to be a man, to be Socrates, to be seen or spoken of, to be 

 a phantom, even to be a nonentity, it must still, at bottom, answer to the 

 same idea ; and that a meaning must be found for it Avhich shall suit all 

 these cases. The fog which rose from this narrow spot diffused itself at 

 an early period over the whole surface of metaphysics. Yet it becomes 

 us not to triumph over the great intellects of Plato and Aristotle because 

 we are now able to preserve ourselves from many errors into which they, 

 perhaps inevitably, fell. The fire-teazer of a modern steam-engine produces 

 by his exertions far greater effects than Milo of Crotona could, but he is 

 not therefore a stronger man. The Greeks seldom knew any language but 

 their own. This rendered it far more difficult for them than it is for us, to 

 acquire a readiness in detecting ambiguities. One of the advantages of 

 having accurately studied a plurality of languages, especially of those lan- 

 guages which eminent thinkers have used as the vehicle of their thoughts, 

 is the practical lesson we learn respecting the ambiguities of words, by find- 

 ing that the same word in one language corresponds, on different occasions, 

 to different w^ords in another. When not thus exercised, even the strong- 

 est understandings find it difficult to believe that things which have a com- 

 mon name, have not in some respect or other a common nature ; and often 

 expend much labor very unprofitably (as was frequently done by the tw© 

 philosophers just mentioned) in vain attempts to discover in what this com- 

 mon nature consists. But, the habit once formed, intellects much inferior 

 are capable of detecting even ambiguities which are common to many lan- 

 guages : and it is surprising that the one now under consideration, though 

 it exists in the modern languages as well as in the ancient, should have 

 been overlooked by almost all authors. The quantity of futile speculation 

 which had been caused by a misapprehension of the nature of the copula, 

 was hinted at by Hobbes ; but Mr. James Mill* was, I believe, the first who 

 distinctly characterized the ambiguity, and pointed out how many errors in 

 the received systems of philosophy it has had to answer for. It has, indeed, 

 misled the moderns scarcely less than the ancients, though their mistakes, 

 because our understandings are not yet so completely emancipated from 

 their influence, do not appear equally irrational. 



We shall now briefly review the principal distinctions which exist among 

 propositions, and the technical terms most commonly in use to express 

 those distinctions. 



§ 2. A proposition being a portion of discourse in which something is 

 affirmed or denied of something, the first division of propositions is into 



* Analysis of the Human Mind, i., 126 et seq. 



