The Principle (or Law) of Identity is usually stated as 'A is A', which can be understood as 'Everything is what it is'. Bradley (PL, Ch. V, p. 141) remarks that, in this form, it is a tautology and says nothing at all.
It does not even assert identity. For identity without difference is nothing at all. It takes two to make the same, and the least we can have is some change of event in a self-same thing, or the return to that thing from some suggested difference. For, otherwise, to say "it is the same as itself" would be quite unmeaning.Stebbing (MIL, p. 470) says
The traditional interpretation of the law is metaphysical. If "A" be regarded as symbolizing a subject of attributes, then the formula may be interpreted as expressing the permanence of substance, or the persisting of something through change.
In referring to Loyola and Bodhidharma in my last letter, I had in mind two 'wilful abandonments of the Principle of Identity'. (i) Loyola: 'In order never to go astray, we must always be ready to believe that what I, personally, see as white is black, if the hierarchical Church defines it so.' (ii) Bodhidharma (or, rather, a modern disciple of his, in an article—'Mysticism & Zen', I think—in The Middle Way): 'The basic principle of Zen is "A is not A".' (Note, in parenthesis, that once people start denying the Principle of Identity the question may arise whether the bare statement 'A is A' is quite as meaningless as Bradley supposes. A lot has been made in modern French writing, philosophical as well as literary, of Audiberti's imaginative phrase la noirceur secrète du lait; and this suggests that it may not be altogether meaningless to assert the contrary, 'white is white'. This might perhaps seem trivial, except that a great deal of modern thinking—including mathematics—is based on a deliberate rejection of one or another of the Laws of Thought, of which Identity is the first. This may be all very well in poetry or physics, but it won't do in philosophy—I mean as a fundamental principle. Every ambiguity, for a philosopher, should be a sign that he has further to go.)
[5.1] The Middle Way: the organ of the London Buddhist Society. [Back to text]
[5.2] Audiberti: the secret blackness of milk. [Jacques Audiberti—1899-1965—was a French poet, playwright, and novelist noted for his extravagance of language.] [Back to text]