Plato was one of the most important philosophers in Western history. Let’s talk about one of his most significant contributions.

Platonic Idealism holds that ideas are the most fundamental form of reality.

The objects around you right now - the screen you’re reading this on, your clothes, nearby furniture - exist in a physical form. But Plato tells us that these are merely physical manifestations of a more essential truth.

Platonic idealism is fundamental to the practice of math. Compare these two math problems:

• 2 + 2 = ?

• Bob has 2 apples. Jane gives Bob 2 apples. How many apples does Bob have now?

The first math problem describes the essential problem. The second describes a physical manifestation of that problem. But Bob, Jane, and the apples don’t make the problem itself more real. The actual 2 + 2 isn’t baked into the apples. The apples merely manifest the more essential math.

Plato famously proved this by pointing to the concept of a tree. Trees exist most essentially as an idea. Nothing perfectly conforms to this idea. But some thing conform to it closely enough that they earn the right to be called trees. Trees aren’t a physical thing; they are a concept that manifests physically.

This allows us to point to things in all kinds of shapes, colors, and sizes, and call them all “tree.”

Some people go a step further, however. They argue that physical things actually arise directly out of ideas.

That’s coming in the next post.