# Name for this logical fallacy? **URL:** \ **Category:** Factual Questions\ **Created:** [August 2, 2020, 11:16pm UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120 "2020-08-02T23:16:10Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![GMANCANADA](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gmancanada/32/2837_2.png) [@GMANCANADA](https://boards.straightdope.com/u/GMANCANADA)\ **Post date:** [August 5, 2020, 10:46am UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120/21 "2020-08-05T10:46:35Z")
I see your point, but I think it’s a pretty subtle distinction. I’ve always understood an ad hominem to mean you are discrediting someone’s ideas based on personal attacks on that person rather than the merits of the idea itself. But I was never taught that ad hominem must _solely_ be rated to a persons character (like your cat example), but it could also be on errors or mistakes they’ve made in the past which call into question their current abilities. I do think it’s illogical to say “because you failed to predict last year’s Oscar winner, your predictions about dark matter are worthless”. That said, in this case the OP’s post seems to be related to retroactively questioning _previous_ good work due to issues _now_. I’m not sure if that time sequence makes a difference in this case. ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [August 6, 2020, 9:11am UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120/22 "2020-08-06T09:11:41Z")
This is why I said “appeal to purity.” It’s pretty much exactly the opposite of “appeal to authority.” ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 6, 2020, 10:55am UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120/23 "2020-08-06T10:55:39Z")
This is the form of _ad hominem_ known as _argumentum ex concessis_. [See here](https://philosophy.lander.edu/logic/person.html#:~:text=He%20adds%20that%20such%20an,has%20taken%20on%20another%20occasion.), for instance: > This form of the _argumentum ex concessis_ occurs when someone is accused of being hypocritical and is personally accused of not believing in, or not acting in accordance with, commitments he has taken on another occasion. ---
**Author:** ![Pantastic](https://avatars.discourse-cdn.com/v4/letter/p/3bc359/32.png) [@Pantastic](https://boards.straightdope.com/u/Pantastic)\ **Post date:** [August 6, 2020, 5:45pm UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120/24 "2020-08-06T17:45:42Z")
> [@griffin1977](#): > > But at the time, as anarchist (or anyone on the left side of the political spectrum) was siding with the western powers (for all their faults) against the militarist German regime such a terrible call? Doesn’t it put him directly at odds with core anarchist principles, specifically opposition to all involuntary coercive forms of hierarchy (like the conscripted armies on both sides) and the existence of states, which all of the Western powers were? I don’t think it’s unreasonable to say “I don’t accept a man who openly rejects the core principles of anarchism as an authoritative source on anarchism”. ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [August 6, 2020, 7:19pm UTC](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120/25 "2020-08-06T19:19:13Z")
> [@Pantastic](#): > > Doesn’t it put him directly at odds with core anarchist principles, specifically opposition to all involuntary coercive forms of hierarchy (like the conscripted armies on both sides) and the existence of states, which all of the Western powers were? I don’t think it’s unreasonable to say “I don’t accept a man who openly rejects the core principles of anarchism as an authoritative source on anarchism”. Yeah in that case I guess it is _argumentum ex concessis_ as Mr Dibble suggests above. Though its difficult to see it as a fallacy really. [Previous page](https://boards.straightdope.com/t/name-for-this-logical-fallacy/917120.md?page=1)