When is it worth it to argue over definitions?

It’s almost always a waste of time debating definitions with people (“semantic debates”).

Just stop for a moment to define terms or switch to using the other person’s definition so you don’t talk past each other. Definitions can be whatever we want them to be, and most of the time the important thing is just that our definitions match closely enough so that we can communicate effectively. Attempts to argue about definitions usually are a fool’s errand.

And yet… there are some situations where disagreeing about definitions or trying to convince the other person to adopt a different definition may be wise:

1. Ambiguity. When someone attempts to use an ambiguous definition, that can cause reasoning about the topic to become sloppy. You can suggest an alternative, more precise definition.
2. Nonstandardness. When someone uses a word in a way that is out of sync with how most people use that word, it can create a lot of confusion. You can suggest switching to a standard definition or using a different word/phrase for what they are referring to.
3. Emotionality. Sometimes, people sneak judgments, offensiveness, or slants into arguments with an emotion-laden word. For instance, “slut” will sound negative to many, even if the speaker insists on giving it a neutral definition. You can suggest switching to a neutral word. Sometimes this can also go in the reverse direction, where someone tries to make something awful sound okay by giving it a very benign phrase.
4. Centrality. Sometimes, a definition is too broad or does not capture the core of what’s under debate. For instance, defining “criminal” as anyone who’s broken ANY law may make it hard to discuss “criminal justice reform.” You can suggest a new definition that’s better focused.
5. Circularity. Sometimes, people will try to win an argument by using an unusual definition that makes them right by definition. For instance, in a debate about the cost-effectiveness of medical care, if someone defines “routine medical care” in such a way as to exclude all non-cost-effective medical care, then, by definition, routine medical care will be cost-effective. In such cases, you can suggest using a widely accepted definition that doesn’t make the other person automatically right (by definition).
6. Benefits. Sometimes, using one definition is more useful or more beneficial to the world than using another definition. In such cases, it might be valuable for you to argue that the other person should switch to using a different definition just for these pragmatic benefits.
7. Shifting. Sometimes people make an unreasonable or false claim using one definition but then, when they’re challenged, they’ll switch to using another definition that makes their claim much more easily defensible (a “motte-and-bailey” fallacy). In such cases, you can argue against their usage of the fallback definition so as to pin down their claims.
8. Objective. There are some special situations (though they’re rare) in which there really is only one good way to define something. For instance, this sometimes happens in physics and mathematics, where any other definition (that’s not equivalent) fails to have the properties we want. I would argue that “evidence” is like this too – I believe there is only one definition that has all the properties we’d want “evidence” to have.

So, most of the time, when disagreements over definitions come up, you shouldn’t debate definitions. It’s simply a waste of time. These conversations usually are unresolvable because there are no agreed upon criteria for deciding which definition is better, and the conversation amounts to pointlessly trading intuitions. Fundamentally, definitions are things we make up, so it’s usually best just to agree on definitions upfront or to adopt the other person’s definition so effective communication can happen.

But, as we‘ve seen here, there are a handful of interesting cases where it’s actually helpful to propose a potentially “better” definition and to try to get the other person to agree to it before proceeding with the discussion!

This piece was first written on March 16, 2025, and first appeared on my website on April 10, 2025.