only acquire meaning when put into a context which, with them, forms a proposition. Thus such pairs of words can be applied to descriptions,[1] but not to proper names: in other words, they have no application whatever to data, but only to entities or non-entities described in terms of data.
Let us illustrate by the terms "existence" and "nonexistence." Given any datum x, it is meaningless either to assert or to deny that x "exists." We might be tempted to say: "Of course x exists, for otherwise it could not be a datum." But such a statement is really meaningless, although it is significant and true to say "My present sense-datum exists," and it may also be true that "x is my present sense-datum." The inference from these two propositions to "x exists" is one which seems irresistible to people unaccustomed to logic; yet the apparent proposition inferred is not merely false, but strictly meaningless. To say "My present sense-datum exists" is to say (roughly): "There is an object of which my present sense-datum is a description." But we cannot say: "There is an object of which 'x' is a description," because 'x' is (in the case we are supposing) a name, not a description. Dr. Whitehead and I have explained this point fully elsewhere (loc. cit.) with the help of symbols, without which it is hard to understand; I shall not therefore here repeat the demonstration of the above propositions, but shall proceed with their application to our present problem.
The fact that "existence" is only applicable to descriptions is concealed by the use of what are grammatically proper names in a way which really transforms them into descriptions. It is, for example, a legitimate
- ↑ Cf. Principia Mathematica, Vol. I, * 14, and Introduction, Chap. III. For the definition of existence, cf. * 14. 02.
