Empiricism is the use of observation of the physical universe as a way to know about it. The opposite approach is to try to divine truth about the universe just by thinking about, using pure logic, without recourse to direct observation.
Empiricism is one of the founding principles of the modern scientific approach.
This philosophy is known as materialism, and excludes the appeal to something outside the physical universe as an explanation for a physical phenomenon. It does not exclude the existence of something outside the physical universe, but only holds that we cannot know about such things with scientific reliability, and therefore they cannot be invoked as special explanations for physical phenomena. Myers-Briggs Naturalism Description Materialism and empiricism together are referred to as the philosophy of naturalism. Naturalistic philosophy does not exclude new and unexplained phenomena, such as ESP, UFO's, or Astrology, but it does hold that any phenomena which is said to exist must have some observable or measurable effect on reality. Special pleading as to why a phenomenon cannot be observed is not acceptable as it violates empiricism, and appealing to forces outside the physical universe violates the principle of materialism.