Philosophy has perennially relied on what seems intuitively right to the reflective mind. It did so already with paradoxes such as the liar or the sorites, and with hypothetical examples like the Ring of Gyges, or the knife withheld from its rightful owner gone mad, or the statue and the lump. And it does so today with trolley cars, split brains, Matrix scenarios, fake barns, and Twin Earth. It is such reflection that drives philosophical controversies concerning reference, or personal identity, or propositional knowledge, or essentialism, or externalism and internalism, whether in philosophy of mind, or in ethics, or in metaphysics or epistemology. What then is intuition? What accounts for its probative force? How is intuition related to truth? This chapter addresses these questions. It articulates and defends an account of intuitions according to which, roughly, to intuit is to be inclined, on the basis of a reliable ability, to believe a modally strong or self-presenting proposition without appeal to the usual sorts of evidence. As such, intuitions can be gainfully used as evidence for and against philosophical positions, and philosophers should therefore not shy away from their use of intuitions as a methodological strategy.