Defeater

Defeater is like when you are playing a game and someone shows you why your plan won't work, and now you need to figure out a new plan. Defeat means you lose or fail.

In an argument or debate, a defeater is when someone presents a reason or evidence that makes you need to change your thinking or admit you were wrong. For example, if you think that all birds can fly but someone shows you a picture of an ostrich and explains that it is a bird that cannot fly, that would be a defeater. It defeats your original belief that all birds can fly.

Defeaters can be important because they help us make sure we have good reasons for thinking the things we do. If we don't consider defeaters, we could believe things that aren't true, which can be a problem in many areas of our lives.