H. P. Grice, "Aristotle on the ambiguity of 'is'"

is Logic, metaphysics The third-person singular form of the verb “to be,” generally held to have three distinct senses: (1) the copulative sense with the syntactical function of joining subjects to predicates in sentences, for example, “This house is white”; (2) the sense expressing identity, for example, “The Morning Star is the Evening Star”; and (3) the existential sense, for example, “There is a house.” There are also other attempts to classify the meaning of “is.” There have been disputes over whether these senses are connected, whether some of them can be reduced to others or are really irreducibly different. Many contemporary analytical philosophers, especially Wittgenstein and the logical positivists, argue that traditional metaphysics is wrong to take being (the participle of to be) as a subject-matter, because doing so confuses the copulative sense and the existential sense of “is.” “Thus the word ‘is’ figures as the copula, as a sign for identity, and as an expression for existence.” Wittgenstein, Tractatus