In this short piece I will attempt to convince you that you already hold a philosophical position on the question: “what is there?”, and that this position determines significantly the way you conceptualize your interactions in the world.
Chances are, you think of yourself as either an empiricist or an idealist. By empiricism I mean that what you think really exists are things, out there in the world, and we learn about them through science. We can know about these things to an extent, but we always must admit that its at least possible we could be wrong. It must be the case that we could be wrong about our theories because we only know them through experimentation, and further experimentation could always call into question aspects of laws, or even the endurance of those laws through regions which were previously untested. What it means for a theory to be true for empiricism is not for it to correspond to the inner workings of reality, but for it to make correct predictions when asked.
On the other hand, you might be an idealist. There are two distinct kinds of idealism: either the entire world is, in a sense, “in your head”, or, your head is the kind of thing the world produces so it can know itself. If you’re an in-the-head idealist you think that your mind or brain or self takes in undifferentiated intuition and applies laws to it such that it appears to have the forms of space and time, length and extension, gravity, taste, etc… Or, if you’re a head-in-the-world idealist, you think the world is the kind of thing which produces heads which have in them the ability to learn the right categories to grasp the inner workings of things. On both of these accounts truth means knowing what really is, the difference being what is, “what really is”? – the world or the head.
These might seem to be differences only philosophers care about – “What exists – the world or your head, or is the world the kind of thing which begets heads for its own purposes?” However, you might notice that they also have implications on how we come to know things, and knowing things is interesting to everyone (and beneficial to the human race). For the empiricist, knowing things just means knowing that the theory one has does the best in experiments. For the idealists, on the other hand, knowing things has more to do with discerning the concepts and categories we use to discuss and interpret the world – because it is actually concepts out of which the world is built. Religious world conceptions generally fit the head-in-world idealist stance, by the way.
One question often posted by empircists is why do they need to take the other two situations seriously, as they don’t seem to benefit us. The reason that the empiricist needs to take seriously the idealist positions is that if they mean what they say when they say they could always be wrong, then they could be wrong about the empiricism as well. Many successful predictions were made by science through the first millennium, for example Ptolomaic astronomy worked brilliantly. No one would take this seriously as an argument that we should not have adopted empiricism in the 17th century as the benchmark way of doing science. So, if we’re serious about getting things right, and more right in the future, we have to be serious about calling our most fundamental beliefs about what there is into question from time to time.