With an eye to the alleged power of inference to prove the existence of God or personal survival, the Cārvāka materialist school recognizes perception as a knowledge source but not inference nor any other candidate. Inference depends upon generalizations which outstrip perceptual evidence, everything F as a G. No one can know that, Cārvāka claims. Testimony is also no good since it presupposes that a speaker would tell the truth and thus is subject to the same criticism of lack of evidence. And so on through the other candidates (Mādhava, Sarva-darśana-saṃgraha). The standard response is pragmatic. We could not act as we do if we could not rely on inference (etc.) albeit inference does depend on generalization that (often, not invariably) outstrips experience. The skeptic himself relies on such generalizations when he opens his mouth to voice his skepticism, by using words with repeatable meanings (Gaṅgeśa, inference chapter, Tattva-cintā-maṇi).