Instrumentalism

Karl Popper defined instrumentalism as follows:

By instrumentalism I mean the doctrine that a scientific theory... should be interpreted as an instrument, and nothing but an instrument, for the deduction of predictions of future events (especially measurements) and for other practical applications; and more specifically, that a scientific theory should not be interpreted as a genuine conjecture about the structure of the world, or as a genuine attempt to describe certain aspects of our world. The instrumentalist doctrine implies that scientific theories can be more or less useful, and more or less efficient; but it denies that they can, like descriptive statements, be true or false.

- Popper 1983, 111-12