I have noticed that people use 'debatable' a lot, while 'arguable' is used quite less.
What's the difference and when should one use one or the other?
According to Merriam-Webster, both these words can be used to refer to something the truth of which is in doubt:
2a : open to dispute : questionable
1 : open to argument, dispute, or question
However, a second meaning for arguable is
that can be plausibly or convincingly argued
That is, arguable can be used to describe a proposition which someone wishes to present as true. Debatable, on the other hand (especially in light of the apparent synonymy of questionable), is often used to describe a proposition which someone wishes to present as false or at least unlikely; see for example Merriam-Webster's sample phrase
the debatable wisdom of going back for another helping from the buffet
which, it seems, would indicate that going back is presented as unwise.
Debatable means it could go either way. Arguable means that one can make a good case to support the issue/opinion.
In some meanings, and idioms
- A debate is a friendly discussion where people take sides.
- An argument, is what happens on Facebook - not very friendly.
In person, a debate is polite speech, yelling indicates arguing.