empiricism

noun

1. A pursuit of knowledge purely through experience, especially by means of observation and sometimes by experimentation.
2. A doctrine which holds that the only or, at least, the most reliable source of human knowledge is experience, especially perception by means of the physical senses. (Often contrasted with rationalism.)
3. A practice of medicine founded on mere experience, without the aid of science or a knowledge of principles; ignorant and unscientific practice; the method or practice of an empiric.