What is this common logical fallacy called?

It’s called truthiness.

Sounds like a tautology or an ad hominen argument to me; I don’t know if there is another term.

Argument by assertion?

I don’t think it’s an ad hominem, that’s a personal attack on the opponent.

@the100thmonkey Copy that. :-)

@janbb Not exactly an ad hominem either, but it has an element of that in it, as it implies “I am right in what I say because you are stupid to oppose it.”

@Fyrius That works! Exactly. Thanks.

Anytime. :)

Ah – logical terms are not my strong suit, @Fyrius, I thought it was an argument based on personal authority which is what he (or she?) was getting at in the second statement. I learn so much here! Thanks.

I think a lot of it will depend on the parties beholden to that blanket statement of it is true because I say so. I feel it is a relative again with in the context and mindset of the person who uttered those words. Kids will say that a lot because they simply do not posses the knowledge yet to better understand what it is they believe to be true…it just is to them. This bring relativism to play where all things could be true within the context of that persons world and then it becomes what is the upside to engaging that persons relative view of their world.

@janbb it can also be an authority fallacy.

@ETpro reading suggestion: Crimes Against Logic written by a Cambridge philosophy prof. very reader friendly, lots of humor, and loads of info packed into a very tiny book (157 pages to be exact)

I have no idea what ya’ll are talking about, and that’s the truth!

It is called “Bull Shit.’

@ChazMaz Now it’s clear! Thank you so much!

my mom calls it being “wrong and strong”

@alive Thanks for the reading suggestion. Crimes Against Logic: Exposing the Bogus Arguments of Politicians, Priests, Journalists, and Other Serial Offenders by Jamie Whyhe. I’ve added it to my list.

@ChazMaz Isn’t that kind of the exact same sort of argument applied in reverse? :-)

@ninjacolin That has a nice ring to it.

@ninjacolin
It’s a fallacy too if you’re right, though.

I believe that you are referring to an Argumentum ad verecundiam, or “argument from authority”.

Appeal to force, unqualified authority, or hasty generalization are the most likely candidates in my opinion. Probably unqualified authority would be the best fit.

This is something I said.
Things I say are true.
Therefore, what I said is true.

Would this be an invalid inductive or deductive argument?

@jerv Generally the appeal to authority is an argument where I say:

1—Dr. X says Y is true
2—Dr. X is an authority
3—Therefore Y is true.

It is not inherently fallacious. In today’s complex world, we can’t all be authorities on everything, and we often correctly cite what an authority says. It only becomes a logical fallacy when we insist our dear Dr. X in infallible and his conclusions unassailable. But what I am talking about is when people who are clearly NOT authorities on Y make the claim “Y is true.” and just leave it hanging there as if their belief that it is true settles the matter for all time.That;s more what @Fyrius said, Argument by assertion.

@cockswain Yes, that is indeed where those who use argument by assertion without recognizing its logical weakness generally respond when their assertion is rebutted..And yes, it is a form of begging the question, in that a propositin which requires proof is stated as if it needs no proof.