Ad hominem on the LSAT
Attacking the arguer is not refuting the argument.
Fallacy vs. flaw, on this site. Our fallacy page on ad hominem teaches the general error. This page is the LSAT version: Flaw questions phrase it as "attacks the proponent rather than addressing the argument" or "rejects a claim because of its source." Note when a person's mention is NOT ad hominem: expert credentials used as evidence are fine.
Start with the general version: the fallacy page. Then come back here for the test-day version.
What it is
An ad hominem flaw rejects a claim because of who made it rather than engaging with the reasons behind it. The person's motives, character, or background are irrelevant to whether their argument is sound.
Careful: pointing out a genuine conflict of interest as one piece of context is not automatically a flaw. It becomes a flaw when the attack substitutes for any engagement with the argument itself.
An LSAT-style example
This example is original. It is not a real LSAT question.
Councilor Park opposes the development, but she owns property nearby, so her objections about traffic should be dismissed.
The flaw: Her property ownership might explain her motives, but it does not touch the traffic evidence. The objections stand or fall on the traffic data, not on who raised them.
How to spot it on test day
- Find the conclusion: is it about the claim, or about the person? If the conclusion dismisses the person, flag it.
- Distinguish: "She is biased, so her data is wrong" (flaw) vs. "Her data is wrong, and here is why" (fine).
- Expertise cited as support is the opposite move and is not ad hominem.
The right answer vs. the trap
The right answer
Usually "attacks the character of the arguer instead of the argument" or "rejects a position because of its source."
The trap
"The argument relies on an appeal to authority." Citing a relevant expert is legitimate support, not a flaw, unless the authority is irrelevant to the topic.
Find your weak flaws
The free diagnostic scores flaw questions separately and shows whether this pattern is costing you points.