One who thinks that all human knowledge is gained through experience. This bit of epistemology
is known, believe it or not, as Empiricism
. John Locke
, David Hume
, and George Berkeley
* were empiricists. John Stuart Mill
was even more of one, as he did not even believe that the rules of math
could be known a priori
See also Logical Positivism, Positivism, Verification Criteria of Meaning
If all of this sounds terribly wrong to you, you might be a Rationalist.
If those weren't enough for you, here's a list of some other famous empiricists.
Willard van Orman Quine
Clarence Irving Lewis
A.J. Ayer (Alfred Jules Ayer)