Concepts
Also, in our daily lives, we're presented and sort of approached by concepts. Concepts are those categories of objects, events, ideas that have some sort of common property; and there are two types we talk about in the book. One is formal concepts. These would be clearly defined by a very strict set of rules or properties. Any number of that formal concept has all of the defining properties, and nonmembers do not. So examples of formal concepts might be a square, what constitutes a prime number, or what constitutes an inert gas. These are things where you either meet the requirements and you are a member, or you don't and you're not. So this certainly exists in our lives, but more often than not we're dealing with and presented with natural concepts. So, as you might imagine, these have no fixed set of defining features; but there might be typical or characteristic features. A member of a natural concept that might possess all or most of those characteristic features is called a prototype. So perhaps a natural concept would be a chair. A prototypical chair, we might think of as kind of L-shaped, with four legs, possibly with arms on either side. If you were to think of a chair, maybe that's the image that came up into your mind; but we can also start thinking about a lot of different types of chairs—those with wheels, those that have sort of strange designs, perhaps artistic designs. Perhaps it's amorphous, sort of like a bean bag, or a nice plush couch that you sit on. Or it could be a straight-backed, hard chair. On and on the list could go. Again, these are examples of natural concepts; and the closer something is to the prototype the more likely it is to sort of evoke that concept in your mind; or you're going to associate it with that thing. But we can also think of natural concepts in terms of games or family, again, to revisit that idea. Depending on your experience with, say, family, or games, that might very heavily influence what that natural concept is to you, what those properties might be.