Realism in general is the position that whether a statement is true or false is something that depends directly on an independently existing reality. For example, to be a mathematical realist is to believe that mathematical entities have their own existence. Since this seems relatively absurd most people are not mathematical realists, but are instead mathematical irrealists, believing that the truth of mathematical statements is decided by some other criterion, such as the ability to construct a valid proof, which doesn’t imply that the mathematical entities themselves have an independent existence.
Here I will defend scientific realism from some of its critics. Scientific realism is the position that the only independently existing entities are those that are involved in the ultimate scientific explanations*, and that nothing else besides them has an independent existence. Scientific realism has some obvious attractions. Since it can explain everything (everything that happens), in principle, it is hard to see what role any other independently existing entities could play. Certainly they couldn’t be required for an explanation, and thus we couldn’t be required to admit that they exist. (Note that we can still talk about other things besides the fundamental scientific objects, we just have to avoid making them something above and beyond those objects; instead identifying particular occurrences of them with particular arrangements of the fundamental scientific objects.) And it certainly seems like a better idea to allow ontology to rest on the objectively sound foundation of science instead of some more questionable category scheme.
But some have misgivings about the way scientific realism does away with the existence of ordinary objects. After all “there is a chair in the corner” is a statement that is not true, strictly speaking, under scientific realism. And realism in general was supposed to be a position that saves our common way of speaking about things from philosophical positions like idealism. But I think this complaint is too hasty. Yes, scientific realism does force us to reconsider our everyday use of language, but unlike idealism it doesn’t force us to view it as completely mistaken. Instead our common use of language can be seen as roughly correct, as simply being too imprecise, but not out-right wrong.
Instead of understanding an utterance such as “there is a chair in the corner” to mean that there is literally some single object, a chair, in the corner, we can instead understand it to indicate that there is some collection of “real” (described by fundamental physics) objects that have the property of appearing like a chair to us. This captures both the ordinary claim that the chair exists, because our new understanding still tells us that something, some collection of particles, exists and the claim that it is a chair by describing this thing as seeming like a chair. So, unlike idealism, this understanding of the “real meaning” of the sentence is not a radical reinterpretation (idealism would tell us that “there is a chair in the corner” means only that we perceive a chair in the corner), rather it is more of a clarification of our original intent, capturing basically the same meaning in terms of the entities accepted by scientific realism.
Of course even this kind of reinterpretation of sentences may leave some feeling uncomfortable with scientific realism, feeling that it has somehow pulled the rug out from under ordinary discourse. But of course this isn’t the case. Even though we aren’t mathematical realists we don’t have problems talking about numbers as if they existed, for convenience. And so there is no problem with talking about chairs, and solidity, and all the familiar components of our world even if we accept scientific realism. We just have to remember that these things exist only as chairs, as solid objects, in the context of our discourse, and that in certain contexts we can’t appeal to things like the property of being a chair, or the property of being solid, except as an abbreviation for a certain scientific description. But this distinction isn’t too hard to make.
* If the physics we have today was the ultimate scientific explanation then these entities would be various fundamental particles. However we don’t know where science will come to a rest, and so we can’t say what exactly the fundamental entities are, but even so there is good reason to believe that at some point there will be theories that explain everything.