Aristotle (384-322 BC)

On Interpretation

Translated by E. M. Edghill

Chapter 10

An affirmation is the statement of a fact with regard to a subject, and this subject is either a noun or that which has no name; the subject and predicate in an affirmation must each denote a single thing. I have already explained what is meant by a noun and by that which has no name; for I stated that the expression ‘not-man’ was not a noun, in the proper sense of the word, but an indefinite noun, denoting as it does in a certain sense a single thing. Similarly the expression ‘does not enjoy health’ is not a verb proper, but an indefinite verb. Every affirmation, then, and every denial, will consist of a noun and a verb, either definite or indefinite.

There can be no affirmation or denial without a verb; for the expressions ‘is’, ‘will be’, ‘was’, ‘is coming to be’, and the like are verbs according to our definition, since besides their specific meaning they convey the notion of time. Thus the primary affirmation and denial are as follows: ‘man is’, ‘man is not’. Next to these, there are the propositions: ‘not-man is’, ‘not-man is not’. Again we have the propositions: ‘every man is’, ‘every man is not’, ‘all that is not-man is’, ‘all that is not-man is not’. The same classification holds good with regard to such periods of time as lie outside the present.

When the verb ‘is’ is used as a third element in the sentence, there can be positive and negative propositions of two sorts. Thus in the sentence ‘man is just’ the verb ‘is’ is used as a third element, call it verb or noun, which you will. Four propositions, therefore, instead of two can be formed with these materials. Two of the four, as regards their affirmation and denial, correspond in their logical sequence with the propositions which deal with a condition of privation; the other two do not correspond with these.

I mean that the verb ‘is’ is added either to the term ‘just’ or to the term ‘not-just’, and two negative propositions are formed in the same way. Thus we have the four propositions. Reference to the subjoined table will make matters clear:

Here ‘is’ and ‘is not’ are added either to ‘just’ or to ‘not-just’. This then is the proper scheme for these propositions, as has been said in the Analytics. The same rule holds good, if the subject is distributed. Thus we have the table:

Yet here it is not possible, in the same way as in the former case, that the propositions joined in the table by a diagonal line should both be true; though under certain circumstances this is the case.

We have thus set out two pairs of opposite propositions; there are moreover two other pairs, if a term be conjoined with ‘not-man’, the latter forming a kind of subject. Thus:

This is an exhaustive enumeration of all the pairs of opposite propositions that can possibly be framed. This last group should remain distinct from those which preceded it, since it employs as its subject the expression ‘not-man’.

When the verb ‘is’ does not fit the structure of the sentence (for instance, when the verbs ‘walks’, ‘enjoys health’ are used), that scheme applies, which applied when the word ‘is’ was added.

Thus we have the propositions: ‘every man enjoys health’, ‘every man does-not-enjoy-health’, ‘all that is not-man enjoys health’, ‘all that is not-man does-not-enjoy-health’. We must not in these propositions use the expression ‘not every man’. The negative must be attached to the word ‘man’, for the word ‘every’ does not give to the subject a universal significance, but implies that, as a subject, it is distributed. This is plain from the following pairs: ‘man enjoys health’, ‘man does not enjoy health’; ‘not-man enjoys health’, ‘not-man does not enjoy health’. These propositions differ from the former in being indefinite and not universal in character. Thus the adjectives ‘every’ and ‘not-’ have no additional significance except that the subject, whether in a positive or in a negative sentence, is distributed. The rest of the sentence, therefore, will in each case be the same.

Since the contrary of the proposition ‘every animal is just’ is ‘no animal is just’, it is plain that these two propositions will never both be true at the same time or with reference to the same subject. Sometimes, however, the contradictories of these contraries will both be true, as in the instance before us: the propositions ‘not every animal is just’ and ‘some animals are just’ are both true.

Further, the proposition ‘no man is just’ follows from the proposition ‘every man is not-just’ and the proposition ‘not every man is not-just’, which is the opposite of ‘every man is not-just’, follows from the proposition ‘some men are just’; for if this be true, there must be some just men.

It is evident, also, that when the subject is individual, if a question is asked and the negative answer is the true one, a certain positive proposition is also true. Thus, if the question were asked, ‘Is Socrates wise?’ and the negative answer were the true one, the positive inference ‘Then Socrates is unwise’ is correct. But no such inference is correct in the case of universals, but rather a negative proposition. For instance, if to the question ‘Is every man wise?’ the answer is ‘no’, the inference ‘Then every man is unwise’ is false. But under these circumstances the inference ‘Not every man is wise’ is correct. This last is the contradictory, the former the contrary. Negative expressions, which consist of an indefinite noun or predicate, such as ‘not-man’ or ‘not-just’, may seem to be denials containing neither noun nor verb in the proper sense of the words. But they are not. For a denial must always be either true or false, and he that uses the expression ‘not-man’, if nothing more be added, is not nearer but rather further from making a true or a false statement than he who uses the expression ‘man’.

The propositions ‘everything that is not man is just’, and the contradictory of this, are not equivalent to any of the other propositions; on the other hand, the proposition ‘everything that is not man is not just’ is equivalent to the proposition ‘nothing that is not man is just’.

The conversion of the position of subject and predicate in a sentence involves no difference in its meaning. Thus we say ‘man is white’ and ‘white is man’. If these were not equivalent, there would be more than one contradictory to the same proposition, whereas it has been demonstrated that each proposition has one proper contradictory and one only. For of the proposition ‘man is white’ the appropriate contradictory is ‘man is not white’, and of the proposition ‘white is man’, if its meaning be different, the contradictory will either be ‘white is not not-man’ or ‘white is not man’. Now the former of these is the contradictory of the proposition ‘white is not-man’, and the latter of these is the contradictory of the proposition ‘man is white’; thus there will be two contradictories to one proposition.

It is evident, therefore, that the inversion of the relative position of subject and predicate does not affect the sense of affirmations and denials.

Chapter 9

Chapter 11