[pdonis]

> GP is correct that the argument contains an informal fallacy

The GP didn't say that.

As for which informal fallacy the GGP's argument contained, I would say it was more like a false dilemma. And the GGP did say "almost tautological", which implicitly recognizes that there might be other possibilities.

> people often express this criticism by saying "your argument is tautological,"

I have never seen this (nonsensical) way of expressing the criticism that an argument is false by saying that it is tautological (and therefore true).

[maxbond]

The point is that it's an overloaded term, which makes it easy to talk past each other.

If you wish to see usages like I described, have a look here.

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...