What is a computer? You’d think that would be a fairly simple question. After all, I’m using one to type this up, I ought to know what it is, right? I mean obviously, it’s a…computer! I mean, it’s got a keyboard, and a monitor, and there’s that box down there…
But what is it that makes all that stuff a computer? Why do we look at it and go, “Oh yeah, that’s a computer,” as opposed to, say, “Oh, that’s just a TV,” or “That’s where I keep the leprechauns at night.”?
Some people try to define the word “computer” just by saying “it’s got such and such parts and they all work this way,” but that’s like saying “airplanes have two wings and jet engines.” It’s true, but I could build an airplane that didn’t have two wings or jet engines. The way something works is not a definition for that thing.
Others try to define it mathematically, but that can also be somewhat limiting, because then only the devices that fit into your mathematical scheme are computers, and there are multiple mathematical models that would all be considered “computers.”
So I turned to the dictionary. That was fun for me–I’m a dictionary fanatic. I’ve got lots of great dictionaries, and there are even more online. The Compact Oxford English Dictionary had the best definition, as it turned out.. I was very happy with it at first, but when I started to think about it, it didn’t quite work. For example, it calls computers “an electronic device,” and we know that computers can be built without electronics.
So I worked to come up with a definition of my own. Strangely enough, the key question that it boiled down to was “Why is a player piano not a computer?” It “processes information” by playing notes from its roll. If you gave it an etching machine, it could “store information” back on to the roll. But despite all that, it’s clearly not a computer. What is a computer doing that is fundamentally different from a player piano, that a player piano could never do?
After about two years, I finally came up with an answer that was both simple and all-encompassing. A computer is:
Any piece of matter which can carry out symbolic instructions and compare data in assistance of a human goal.
And that, my friends, is really it. My only thought left is whether I should say “a series of symbolic instructions” to more clearly differentiate it from a calculator. What do you think?