At an everyday level, we seem to subscribe to a from of strong realism which doesn't leave any room for skepticism. We are certain that individuals who hear voices in their heads or who have hallucinations are dysfunctional and something is wrong with their sense data. We can immediately attribute such occurrences to some neurological problem or drug that needs to be cured medically.
Similarly individuals or groups who claim to be communicating with the dead or with extraterrestrials, or with the Valhallic deities, are deemed to be dysfunctional, even if their sense data per se is not faulty. We know for certain that there is something irrational/non-logical about their interpretation of their sense data and that they need to change their worldview.
On an every day level, we are subscribing to a hard realism and some sort of correspondence theory of truth.
And yet at the philosophical level, it is very hard, maybe even impossible to have such epistemic certainty. There are serious challenges to metaphysical realism, scientific realism, the existence of other minds, the existence of matter, etc...and there is also the fact that all observations are theory laden, and that all theories are underdetermined. Skepticism and relativism seem very difficult or impossible to refute.
- What is the difference between common sense everyday realism and metaphysical realism?
- If X has consumed LSD (unbeknownst to me) and now sincerely claims that he is flying around the park, I know for certain that the problem is with his perceptual apparatus (even if I might not know the cause of the problem), not with me and him having competing theories about gravity and how each of us perceive the park. Why is such certainty possible?