Page "Epistemology" Paragraph 48

Externalists think that factors deemed " external ", meaning outside of the psychological states of those who gain knowledge, can be conditions of knowledge.

For example, an externalist response to the Gettier problem is to say that, in order for a justified true belief to count as knowledge, it must be caused, in the right sort of way, by relevant facts.

Such causation, to the extent that it is " outside " the mind, would count as an external, knowledge-yielding condition.

Internalists, contrariwise, claim that all knowledge-yielding conditions are within the psychological states of those who gain knowledge.