Do Chairs Exist?

[vulcanlogician]

Why?

I didn't realise that anyone took the idea of universal-forms-out-there-somewhere seriously.

Shows what I know.

I don't, really. At least, not exactly how Plato articulated them. 

I find Plato enjoyable to read, so I've probably given the idea more consideration than most. You gotta factor that in as well. He's an excellent writer who really likes to get his reader considering his positions. For that reason alone, he's a great philosopher. Way more about engaging his readers' intellects than he is about convincing them of his positions.

When a modern reader contemplates Plato's forms, it's never about accepting his entire theory as presented. Instead it's about discovering if there are things that are universally true and immutable. Do such things exist? 

It's not too hard to find examples of universally true things if you start thinking about it. For instance, you can come up with immutable "eternal" truths about Euclidean space. For right triangles you can say, if angle A and B equal x, then angle C must equal y. This is an immutable truth about Euclidean space, and very much something Plato would consider a truth gleaned from an understanding of a form.

Above the entranceway to Plato's Academy stood a sign which read, "Let no man enter who is ignorant of geometry." Plato prized mathematics and thought it was key to understanding the universe. I think Plato would be quite pleased to see that we have an enterprise called "science" in which we use mathematics to describe everything in nature. Plato would look at the various equations we use to understand physics and say, "this equation expresses a fundamental truth..."

Now many scientists will point out that no equation we have today explains nature fundamentally. Even Einsteins equations (as good as they are) are ultimately inaccurate. Afterall, they can't describe the physics within a singularity of a black hole. A scientist might want to say that we never arrive at universal Platonic forms, and dismiss the idea for that reason. But even Plato understood that we cannot have perfect knowledge. 

Merely by saying "one theory is better than another" or "this theory is more true than that theory" we are invoking Plato's forms to some degree. It means that there is some kind of metaphysical thing called "truth" or "accuracy" which we perceive via our rational intellects that guides the process of science and allows us to distinguish good theories from bad ones. That is the main thrust of what Plato put forth. And I think there's something to it.