Existence of an external reality

How often do you run across someone who insists that "so-called reality" is an illusion, that we can't prove that it exists, that everything might be a dream or hologram or hallucination, or that "your reality is not my reality"? Actually, in Boulder, CO, quite a lot. The reason this keeps coming up (as it has for centuries) is that it is difficult, if not impossible to prove beyond a shadow of a doubt that the reality that seems to be around us actually exists independently of us. In the next few sections, I will outline the many ways that have been presented over the years to give us confidence that it really is there.

It’s hard to imagine how anyone could question reality’s existence, which is close to questioning existence itself. But they are out there: solipsists who doubt all existence, and even doubt that minds other than their own exist, Idealists, some mystical eastern religions like Advaita, and adherents to fringe pseudo-religions like the Unitarian Church's “Course In Miracles” who at least agree that we all have minds, but that the physical world might be an illusion. One could wisecrack that this tendency to deny reality might have been bred out of the human race over time if there were a genetic component to such beliefs – that they would have stepped off the curb in front of a car (or chariot, or saber toothed tiger). But I imagine that even these people look both ways before crossing the street. When it comes to actually living in the world, we all interact with it as if we were realists, regardless of what other philosophies we may profess.

Fair warning - I approach this discussion from the point of view of a Philosophical Realist, also called Metaphysical Realism. I believe that "truth" is measured by the mind's correspondence to reality. I accept that the world is pretty much like our senses, and our science shows it. To give it another name, I am also a Philosophical Naturalist - I think that the observable universe is all there is, and is all that we need to concern ourselves with. There is an external reality that exists independent of our senses, and is there when we are not present to observe it. Other metaphysics (Idealism, Subjectivism, Relativism, Solipsism, Dualism, Monism, etc) so blatantly contradict common experience or are so obscure that I can't accept them. The only philosophical choice which the evidence of our experience supports with every action we take is Realism. When we look both ways when we cross the street it is because at our core, we are all realists.