Task: Text Categorization
Input (English): The definition of this concept was called into question by Edmund Gettier, who attacked the established doctrine that had dated back to Plato's Theaetetus. Externalists argue that it is possible to possess it unawares, while internalists deem it a matter of the correct relation of ideas in the mind. Foundationalists claim that one must have correct basic beliefs to possess it, while coherentists argue that it is a matter of the interlocking of beliefs. FTP, identify this concept which, according to Cartesian skepticism, humans entirely lack.
Output (English): Social Science