Attacking your opponent’s character or personal traits instead of engaging with their argument.
The billboard above was erected in an attempt to draw a connection between people who commit terroristic atrocities, such as Ted Kaczynski (the unibomber) and belief in global warming. Since he is a terrorist, his opinion on climate change just can’t be right.
The direct translation is “to the man”. I think everyone knows how easy it is to fall into this trap, and also how often this fallacy is misused.
You can’t be good at managing finances, you live in your Mom’s basement!
A common form of this fallacy is also frequently present in the arguments of conspiracy theorists (who also rely heavily on ad-hoc reasoning). For example, they may argue that the government must be lying because they are corrupt.
It should be noted that simply calling someone a name or otherwise making an ad hominem attack is not in itself a logical fallacy. It is only a fallacy to claim that an argument is wrong because of a negative attribute of someone making the argument.
“John is a jerk.”
Although this may or may not be true, this is not a fallacy because it does not assert the conclusion is false as a result of John being a jerk..
“John is wrong because he is a jerk.”
This is an ad hominem fallacy because it claims John being a jerk is related to his conclusion being true.