What is the false dilemma (false dichotomy / black-and-white thinking) fallacy?

Presenting only two options as if they were the only possibilities, when others exist, then forcing a choice between them.

The pattern: "Either X or Y; not Y; therefore X" — which is valid only if X and Y truly are the sole options. The fallacy is artificially shrinking the range of possibilities so that ruling one out "proves" the other.

"Either we ban this app entirely, or we accept that our children's data is harvested. We can't accept the data harvesting, so we must ban it."

This ignores middle paths — regulation, privacy settings, age limits, alternative apps. Contrast a genuine dilemma: "Bill is either dead or alive; he's not dead; so he's alive" — there really is no third option there.

Tip: Counter it by asking "Are those really the only two choices?" Real either/or splits exist (on/off, alive/dead); the fallacy is manufacturing one where reality offers a spectrum.