Logical Fallacies

A field guide to arguments that sound persuasive until you look at how they work.

A quick field guide

Everyday examples make the pattern easier to spot. A flawed argument can still reach a true conclusion; the fallacy is in the reasoning used to get there.

Ad hominem

Attacking the person making a claim instead of addressing the claim itself.

“Her proposal about bus routes is wrong; she can’t even organize her desk.”

Straw man

Changing someone’s position into an easier one to attack.

“You want a shorter meeting, so you clearly don’t care about the project.”

False dilemma

Presenting two choices as the only possibilities when other options exist.

“Either we keep this exact schedule or the whole event will fail.”

Hasty generalization

Drawing a broad conclusion from too few examples.

“Two buses were late this week, so the bus system is never reliable.”

Slippery slope

Claiming that one step will inevitably trigger a chain of increasingly extreme events, without enough support for that chain.

“If we move one deadline, soon no deadline will mean anything.”

Circular reasoning

Using the conclusion as its own support instead of giving independent evidence.

“This rule is fair because it’s the right rule to have.”

Post hoc

Assuming that because one event happened before another, it caused it.

“I changed my screensaver, and then the sales improved. The new screensaver did it.”

Appeal to authority

Treating an authority’s view as decisive evidence outside the area they know—or without checking the evidence.

“A famous actor recommends this investment, so it must be safe.”

Spotting a fallacy is a reason to examine the reasoning more closely, not proof by itself that the conclusion is false.