Infinite regress.

Here is an image that tries to describe this concept. It indicates a way of logically arguing when, to explain something, one uses a term, which it makes necessary to refer to a new term, and this to a further term. Plato, the pioneer, deals with it in the problem of the third man. In this undertaking follow Davidson, Frege, Wittgenstein, Quine, Russell and Strawsone.