I need some help from Philosophy-oriented folk in answering this question, which I've been sounding off about in the Relativity forum in the thread "Raindrops and Gravity". After having a few of my deviant ideas ironed out there by people who know much more than I do, I've arrived at the following understanding: First, there is no need to doubt a bricklayer's view of "reality" in his immediate vicinity. He is likely to answer by hefting a brick, and tell you "that's what's real". And you'd better believe him. Second, you may describe this definition to a friend, and ask him to give you a more sophisticated example of reality. He could describe the new Ferrari he has over at his house, and tell you that it is "really" there. If you doubt him, you could go over and drive it around, if he'd let you. Third, if you ask a physicist whether a magnetic field is "real", he could try to convince you that it is by showing you iron filings sprinkled on paper above a magnet. You might then believe his claim. Fourth, you could approach an engineer who is building a machine to accelerate particles. He will tell you that Special Relativity (SR) requires him to take into account an increase in mass of the particles as they are accelerated. If you ask him whether this is "really" so, he would assure you that his pay cheque depended on his accepting that SR describes an observer-dependent reality. Fifth, you might ask a General Relativist if Spacetime, or the Riemann curvature tensor, were part of objective reality. He would insist that the latter is a geometric object in the former, that both are part of a four dimensional reality which is independent of any observer. Sixth. I don't know how a mathematician or a string theorist would define reality. I've arranged these "straw views" in increasing order of abstraction regarding a definition of reality. I don't which, if any of them are true. But my own conclusion is that in the end reality is nothing but a Platonic model in one's mind that matches, in as many ways as one can devise, the fullness of experience. I'd like to know if philosophers consider such simple-minded views on the subject.