I have often heard this type of argument:
You are criticizing X using well-researched facts and arguments.
Your interlocutor states that Y is much worse, with equally well-researched facts and arguments.
Your interlocutor uses their argument that Y is worse to suggest that X is, in fact, good.
X and Y are linked in a general sense:
- two alternative medicines (homeopathy & chiropractics).
- two politicians (May & Corbyn).
- two historical figures (Hitler & Stalin).
This logical fallacy asserts that because Y is much worse than X, therefore X is good. What is this logical fallacy called?
Clearly in a binary choice, the lesser evil should win: X is bad, Y is worse therefore you should chose X. ⚠ This is not what this question is about.⚠ Please re-read the last sentence.
This logical fallacy asserts that because Y is much worse than X, therefore X would be a good thing. Not that it is a better choice, less-worst choice, the only choice but that it is a worthwhile choice on its own.
In addition, there might not be just two choices or one might not even be asked to make a choice: the fact that Y is worst makes X good regardless of X's merits.