What is the idea that only visible things are real?

Answer 1

Eliminative materialism is the philosophy that says that only that which can be observed through the senses or experimentation can be said to be real.

In many ways, modern scientific knowledge supports this.

However, there are still certain things that cannot be observed yet, and only hold a basis in terms of effects or mathematical constructs extrapolated from physical effects (such as emergent phenomenon of consciousness from neural activity, superstring theory, etc.). Many of these phenomena are backed on rational bases, and it is believed that we simply do not currently possess the means of testing, observing, and quantifying various aspects of these phenomena yet (emphasis on the word "yet").