When in a debate, someone claims it must be true because smart people believe it, which logical fallacy is that?

I see it as a version of appeal to authority.

Thanks. That seems to be the closest thing I found, though it doesn't really fit the definition.

I don't know which logical fallacy, but it clearly has a tie in to peer pressure. Also, the most desperate phrase for trying to prove A point without having actual proof is, "Everybody knows that . . ."


Something is true because "it is" and no matter how many believe or how many disbelieve, that something is still true. There may be safety in numbers, but it does not follow that there is automatically truth in numbers.

It's an appeal to irrelevant authority, to be exact.

Mormons just love this one, don't they? But they totally forget that even extremely intelligent people can be indoctrinated, and are just as susceptible to cognitive dissonance. All the smarts in the world don't matter when a person is brainwashed from birth to believe in nonsense, and furthermore are taught never to question that nonsense.

Thanks. Yes, they do love it and it's annoying as hell.

All smart would agree on every issue if being smart meant infallibility. The reality is that opinions among smart people are as wide and far reaching as they are with those of average or below intelligence.

Plus, you can always come up with someone even smarter that doesn't believe or accept it.

It begs the question as to what defines a "smart" person.

Does the speaker mean "popular?" The two are often confused. That would be ad populum.

Then, there's the ill-conceived basis of "smart people."

Really? Which ones? All of them?

Some smart people may believe it, but some smart people most decidedly do not.

And this-

https://en.wikipedia.org/wiki/Existential_fallacy

Just because someone says IT does not make IT true!

Just because many people believe IT does not make IT true!

Only when supported by unchangeable evidence can the possibility of IT being true be considered

This argument doesn't work because you find smart people in ALL religions, churches, and cults. A Muslim can claim there are many smart Muslims so Islam must be true.

It could also be argumentum ad populum (argument to the the people or argument by consensus), unless what you refer to as "smart people" exclusively means "experts" or "authorities".

I don't think they meant experts exclusively but they would be included.

You're dealing with a fallacy combo. Argumentum ad populum + appeal to authority.