What do you call a person who believes only what he sees?

A person that only believes what he/she sees cannot rule out the possibility of seeing God in the future and would probably be called agnostic. == == You could refer to such a person as a skeptic. A skeptic is one who is likely to question very many things. A person who does not believe in the supernatural, but only believes what can be proven is a Bright.

Here is probably what you are looking for:

em·pir·i·cism or em·pir·i·cist n. # The view that experience, especially of the senses, is the only source of knowledge. # ## Employment of empirical methods, as in science. ## An empirical conclusion. # The practice of medicine that disregards scientific theory and relies solely on practical experience.