As time goes by

Languages change through time. This simple statement seems to be equally trivial and easy to verify. Actually, it is a major intellectual challenge. For its appreciation requires two things, a notion of time and an understanding of how languages can be distinguished one from another. Just one of them is sufficient to cause a headache, taken together they pose a serious problem. The general form of the problem is this. The statement

(1) x changes in time.

presupposes an existential statement such as

(2) x exists.

But if x changes it is no longer x but x′. To deal with this difficulty, we might just modify our terminology and rephrase (1) as

(3) x is transformed into x′ in the course of time.

However, this is no solution to the problem because we have to come to terms with what distinguishes x from x′ and how we get from x to x′. Our original statement (1) is intuitively cogent, since experience tells us that yesterday's English and even last year's English has a lot in common with today's English.