Full Idea
The process of pure intuition does not measure up to the standards required of a priori warrants not because it is sensuous but because it is fallible.
Clarification
'Warrants' are guarantees of knowledge
Gist of Idea
Intuition is no basis for securing a priori knowledge, because it is fallible
Source
Philip Kitcher (The Nature of Mathematical Knowledge [1984], 03.2)
Book Reference
Kitcher,Philip: 'The Nature of Mathematical Knowledge' [OUP 1984], p.53