The difference between having an argument and having a quarrel

Both involve disagreement and raised voices are optional in each, but only one of them can end in somebody learning something.

An argument, in the useful sense, is a claim with reasons attached. Someone says the shorter route is better, and gives grounds: fewer intersections, lower speed limits, no school zone. You can inspect grounds. You can agree that the school zone matters and dispute that the speed limit does. The disagreement has a shape, and the shape tells you where to push. A quarrel has no shape. It is two people asserting positions with increasing volume, and it ends when one of them is tired or the topic is abandoned. Nothing has been tested. The person who spoke last has not been shown to be right about anything except their own stamina.

The tell is usually easy to spot once you look for it. In an argument, you can state the other person's reason in a sentence. In a quarrel, you can only state their conclusion. If you find yourself able to say what someone thinks but not why, either they have not told you or you have not listened, and both are worth fixing before anything else happens. A useful move is to simply ask: what makes you say that? Not as a challenge, in the tone people use when they mean the opposite, but as a genuine request for the missing part.

Quarrels are not always a failure. Sometimes the disagreement is not about facts at all but about what matters, and no amount of reason giving will settle whether you would rather have a quiet drive or a quick one. But it helps enormously to know which of the two you are in. A great deal of frustration comes from running an argument against someone having a quarrel, or from earnestly producing evidence when the real dispute was never about evidence. Naming the situation is not a way to win it. It is a way to stop wasting an afternoon on the wrong activity.