Someone on Quora asked this question: can every philosophical debate be ruined by simply asking to provide a definition of the debated topic?
I think that a lot of people get carried away by talk of “defining your terms” because it seems to make things simpler. It’s easy to see people constantly talking past one another and think that the whole problem could have been avoided if they had both just defined their terms in the first place. It’s even more tempting to look back at the history of ideas — which, after all, is mostly written by people in funny clothes who couldn’t even build computers — and dismiss it all as a failure to define one’s terms, or as some other obtuseness of method. And you’d hardly be the first person to dismiss history in this way. Ever since the dawn of modernity, it has been fashionable to declare all of history up to the present as the history of errors and claim to have found a method sufficiently acute to refute them all. Part of transitioning to postmodernity is understanding how dumb it really is to say something like that, but that’s another discussion.
Unfortunately, this misses the point: definitions emerge as the outcome of a process of deliberation, not at the outset. That is to say, by the time we get to a definition, we already have a whole body of prior judgments that make that definition possible. If you define knowledge as justified true belief, you’re presupposing that your audience knows what justification, truth, and belief are. Moreover, you’re presupposing that they have a particular understanding of those terms, one similar enough to your own that you can make that definition and they’ll get what you mean. The meaning of a word is not an “atomic” thing that inheres in the word itself. Words take their meaning from context, and this context includes both words and the practical contexts they occur in; “check” means something very different in chess than it does in hockey because you don’t play those two games the same way.
If that’s all too abstract for you, then think of it this way: suppose you’re speaking with Socrates. You say that you know something. Socrates responds, “But what is knowledge?” You can’t very well respond “Silly Socrates! Define your terms! Just give me a definition of knowledge and I’ll tell you!” because that misses the point. It misses the point because, by asking you what is knowledge, Socrates is inviting you to participate in a discussion where the whole point is defining knowledge, or investigating its nature in a way that leads to a definition. The definition cannot emerge at the outset of this process, but must emerge as the outcome. If I invite you to a discussion where we define knowledge, you can’t respond by demanding a definition. It’s as if I were to invite you to cook a meal with me and you responded that I must give you the cooked meal first. It completely misses the point.
This is where someone might stop me and say something like this: “Now wait a minute! How am I supposed to deliberate about something if I don’t know what it is? Without a definition, you cannot possibly know what a thing is, so how can you deliberate about it?” But of course, that isn’t true at all. You absolutely can know what something is without a definition; as a child, you understand words like “yes”, “no”, “dog”, “cat”, “water”, “thirsty”, “food”, and “eat” without your parents needing to define them for you. At most, maybe somebody pointed at a glass of water and said “That’s water” — what philosophers call an ostensive definition — but for the most part, you just picked up your vocabulary by osmosis. For that matter, humanity existed for thousands of years without dictionaries and we did just fine. The presence of dictionaries and definitions has ruined many people’s understanding of language; we think that the dictionary dictates how language works, when really it’s the other way around. Talking about something without knowing the definition isn’t some kind of exercise in absurdity. It’s the default way of speaking. And a whole lot of talking has to happen before there can be a definition.
(Incidentally, the concise definition you get in a dictionary does not capture the fullness of a word. “Ruthless”, for example, is defined as “Without mercy” but it has connotations of persistence that the dictionary never mentions. To “ruthlessly hunt them down” means to hunt them down with cruelty and persistence. You don’t “brutally’ hunt someone down, even though many dictionaries list “brutal” as a synonym of “ruthless”.)
Once you realize how artificial definitions really are, and once you realize that they do not really capture the living core of language (which is intimately connected to praxis), you see how silly it is to demand a definition right at the beginning of a discussion. The only time you can ask for a definition is when you can reasonably expect everyone to agree on what the definition is. And that, in turn, assumes that we either implicitly know it already and haven’t articulated it, or that we’ve never heard of it and are willing to believe whatever you say about it. So no, asking for definitions is not a panacea that cures the illness of philosophy. Believe me, better men than you have tried.
Your definitions may not be even close to mine.