Why did I make a website to write about definitions, especially since all these words have already been defined in the dictionary?

Most existing definitions are completely acceptable—they’re simple and straightforward and unambiguous. But there’s also a surprising amount that don’t quite work. I’d be reading an article, on the ways marriage is changing for example, and the author would argue something that would make me think, “Well, that depends on what the definition of marriage is.” So I’d do a little googling and find the definition: “the state of being united as spouses.” That would then prompt me to look up “spouse” in the dictionary, which is defined as “a married person.” Now I’m back to square one. I don’t have any better understanding of what a marriage is now than when I started.

In everyday usage, these kinds of things generally aren’t a problem, but then sometimes there are arguments based entirely on people using different definitions of the same word. If two politicians are arguing over marriage, and they have different ideas of what the word means, then they’re unlikely to find common ground. I’ve also found that if I explore a term and really try to craft a good definition, I often discover an underlying logic to the idea that doesn’t always come through in the dictionary version.

Let’s define the word chair to see what this is like. It should be straightforward, right? The dictionary definition is “a separate seat for one person, typically with a back and four legs.” This isn’t circular, but are there situations where this definition wouldn’t work? Are there examples where the answer to the question “Is this a chair?” might not be obvious, where most people wouldn’t agree on the answer, or, more interestingly, where people would agree but wouldn’t be able to explain why? Here are some examples where our instincts about what a chair is might not match the dictionary definition:

• Take a park bench. Maybe it’s cast iron with four legs and a back, for two to three people. Now imagine making it thinner until it can only fit one person. Is this a narrow bench now, or has it become a chair?
• Imagine a barstool. It’s probably a high seat with three legs. Now add a back to it. Has it become a chair, or is it still a stool?
• What about a “kneeling chair,” which doesn’t have a back at all, rather just extra pads to lean on? Should that really be called a chair?

Even though we might think it’s easy to define chair at first, it’s also just as easy to think of examples where the definition doesn’t work. What is it that makes these examples not clear? Often a definition will include too much description, too much about what things are usually like, instead of focusing on what is universal. When I first read the dictionary definition of chair, I immediately had a problem with the word “typically,” since it really gives us no useful guidance. If I see something without a back or without four legs is it just a non-typical chair, or is it something else entirely?

If we get rid of “typically,” does that improve things? It’s a good start because now we’ve got three concrete features a chair needs to have:

• For one person
• Four legs
• A back

Unfortunately now it’s easier to think of things we’d all call chairs, and yet they don’t fit this definition, such as an office chair with five legs on wheels. I think the only universally accepted feature of a chair that’s not going to give us any problems is that it’s “for one person.” Here’s a simple thought experiment: imagine a couch, which clearly isn’t a chair, and then picture it getting narrower and narrower. At some point, it becomes a seat for two people, which we’d call a love seat, which is also “definitely not a chair.” If it gets even narrower, it would become an upholstered chair or an armchair—definitely something we’d all recognize as a chair now.

The switch to being designed for one person is key here, so that’s a good part of the definition to keep. And now we’ve got the idea of “designed for” as part of it too. For example, if two people squeeze onto a single chair that was designed for one person, it doesn’t stop being a chair. It’s not how it’s used or what it’s capable of but rather what it was designed for that matters, so we’ll include that as well.

Let’s explore the idea of “being designed for something” further. Why are chairs often designed with four legs and a back? Some seats, like park benches, are meant to be bolted or cemented in place and will often only have one or two legs; they don’t need more legs to stand. A chair needs to have at least three legs because it’s designed to be moved around. It could easily have five or more legs—the number isn’t important. What is important is that it can be moved and not tipped over easily.

Of course a seat only needs three legs to be stable, so why do chairs usually have four? Looking at the design of most chairs, it’s probably because they almost always have backs. A stool can have three legs because the person sitting on it isn’t exerting any sideways forces. A chair would often need four or more legs to support those forces without typing over. This becomes clearer when we look at office chairs that swivel and have wheels. If you don’t know which way the person is going to be moving or leaning back in a chair, then you’d want to design extra legs to make sure it doesn’t tip over. Again, the key idea for a chair isn’t how many legs it has—it’s that it’s been designed to provide stability as people lean back in them. So, we don’t care so much about the number of legs, but that people will be leaning against some part of them.

While we’re looking at different kinds of chairs, we could try to see if we can make the definition encompass “kneeling chairs,” as well. It could be that kneeling chairs aren’t chairs at all though; maybe they’re just seats that we’ve been calling chairs by accident because we didn’t have a better definition before? Or perhaps there’s some underlying reason why we’ve all wanted to call them that even though they don’t look like other kinds of chairs. If our definition can include kneeling chairs without messing with the other aspects of the definition, it would be much more useful.

So, what makes a kneeling chair a “chair” and not a “seat”?

Kneeling chairs don’t have backs, but they do support us. Instead of saying “with a back,” a simple change is to be a little more general with this idea and say that a chair “provides support.” This is why chairs usually have more legs, they’re supporting someone, and have to be stable even with those sideways forces. Though it’s tough to tell immediately if this is a good modification. On the one hand, using more general terms like this could capture “truer” examples in the definition. On the other hand, it might open up the definition too much to include items we don’t want to call chairs. But I think this works because there are more extreme variations of chairs that could fit now too, like bean bag chairs. They don’t have any legs or a back, but they do offer support for one person, and they’re just amorphous blobs! Using this new definition it makes sense why people would want to call them chairs. And I can’t think of any other unusual things that would count as chairs under this broader description, so replacing “with a back” with “provides support” seems like a great change.

Making these kinds of adjustments to include kneeling chairs and discovering that it means we also get to include bean bag chairs is what I like about exploring definitions. Most people would’ve probably agreed that the original definition of chair (“a seat for one person with four legs and a back”) was fine, but then they’d also agree that bean bag chairs should be classified as a kind of chair. Our new definition, “a seat designed for one person, to be movable and provide support,” solves this conflict. And it solves the problem in a way that makes it easy to explain why everyone refers to kneeling chairs and bean bag chairs as “chairs,” and there are no contradictions or vague terms or circular logic. If two politicians were to get into a heated argument about what counts as a chair, I’d hope that this definition would help resolve it for them. A narrow park bench isn’t a chair because it isn’t designed to be moved around, but a chair with a single leg on a weighted base would be. A bar stool with a back is a chair—as long as it doesn’t tip over when you actually use the back, otherwise the back doesn’t really provide support; it’d just be there for looks.

Chair: a seat designed for one person, to be movable and provide support

My goal with this site is to create clear definitions for complex terms, terms a lot more complicated than chair. I want to dig into the universal concepts that we all intuitively understand when we use a word but that haven’t been clearly articulated before. Some of the definitions will be fun, some might be controversial, and I’m sure I’ll have to go back and revise some after thinking about them more. But I hope you’ll find the process as fun and interesting as I do.