On the one hand, it is claimed that one should not depend solely on the judgement of people of authority, but rather try to verify their opinions and learn independent thinking. It is claimed that the fact that a person of authority says X does not yet constitute an argument for X.

On the other hand, many times it would seem that the contrary is true. Trying to apply one's own reasoning can lead to preventing from learning; as it would seem that, especially in the first stages of learning, absorbtion of other people's knowlege, rather than questioning it, is a necessity - even if the learner cannot yet prove this knowledge themselves. Also, insisting on proving or understanding each piece of accepted knowledge is practically infeasible.

In some areas, proponing the recourse of authority has been brought up to eleven. In cryptography, for example, it is strongly encouraged to only use tools brought by experts. This general prohibition of doing virtually anything on one's own seems even more harsh than the usual recourse to authority, which only prohibits doing what experts explicitly discourage. (source: see eight numbered links in the top of this question).

It would seem that statements really are much more likely to be true just because an expert said them, as opposed to statements said by the ignorant - and this seems precisely what argument from authority fallacy disclaims.


The word "fallacy" gets bantered around in lots of ways (See this meta question for more on that). But on the simplest level in common parlance "that's a fallacy!" is an awesome weapon that wins arguments; in philosophy, it usually just starts an argument or shows that two people greatly disagree.

Before I go on, I should mention there's a special group of fallacies that occur in deductive arguments. In these cases, someone has made a traceable error where they claim they've justified a premise that they haven't (e.g. affirming the consequent, denying the antecedent). In this case, if it's formal logic, people agree that someone made a mistake a move on.

For almost all other types of fallacies, things are not simple. Instead, they are "informal fallacies" which is to say mistakes people make (or others purport they make) in making arguments with words).

In the case "appeal to authority", the question at hand is whether both parties to an argument should/do consider someone to be an authority.

  1. Jeff says you have cancer.
  2. ???
  3. Therefore, you have cancer.

Is an argument that goes very differently depending on whether 2 is "Jeff is a oncologist looking at your chart" or 2 is "Jeff is a three year old". If we think whatever is behind 2 is not a valid authority or source, then we would call it an "appeal to authority" or more precisely "a fallacious appeal to authority." The problem comes in when people genuinely disagree about what counts as expert knowledge or authority on a problem -- or if we think it's even possible or necessary for some type of argument.

In the place you link presumably the point is that you want an argument that doesn't appeal to any authority to explain why scrpyt(bcrypt(x + salt)) is bad security and most people are instead giving arguments about why some authority thinks this type of thing is bad. The people offering these presumably think they are sufficient; you don't -- ergo you fight about whether this is fallacious.

It would seem the way to prove it without using any authority in the case you care about would be a mathematical proof, but then (and I have no idea) a challenge is whether (a) anyone can offer one, (b) you (or I) could understand it. Finding a mutually accepted authority is a way to skip the impossible task of getting everything without accepting authorities.


The fallacy has to do with the idea of appealing to an authority being applied to deductive reasoning. A deductive argument, or a valid logical argument, is one where if all of the premises are true, then the conclusion has to be true. In a literal way, it is assured to be true as well. This property is sometimes called the preservation of truth. Arguments that have this property are valid arguments, fallacies do not have this property, and the appeal to authority is an example of a fallacy because of this.

So how this applies to the fallacy of appeal to authority is that it is not the case that an authority will always be correct about a subject. The argument looks like this:

Premise: Jane Smith is an authority on Psychology.

Premise: Jane Smith says that the human mind is not complex.

Conclusion: Therefore, the human mind is not complex.

We can see that this argument does not work. First, there is a hidden assumption, along the lines of “whatever an authority says about a subject is true” but this is obviously false, there are many examples of authorizes being wrong. Without that hidden assumption, it is possible for the two premises to be true but the conclusion to be false. The human mind is complex, we know that much about neuroscience and psychology. Jane could conceivably be an expert and hold an incorrect view about the subject, so the argument is not valid. Notice that in this example, I chose a pretty extreme case (it’s unlikely that an expert is psychology would believe that the human mind is not complex), but there are many examples from, say, mathematics where an authority believed they proved something that they actually didn’t, so they held a similar false belief about their field even though they’re an authority on it.

Additionally there is a stronger, a little more informal, justification for why the argument is a fallacy: the fallacy asserts that because someone is an authority, the statement is true. As in, what makes the statement “human minds are not complex” true? The fact that an authority, Jane, said it. If that statement were true, it would be because of facts about the human brain, not just the fact that some person said it was so.

The appeal to authority fallacy doesn’t mean that we shouldn’t trust authorities, it means that the fact that an authority says something is not the reason that statement is true, nor does it mean that statement is true.

Premise: Frege is an expert in logic

Premise: Frege believes Basic Law V is consistent

Conclusion: Therefore Basic Law V is consistent

It is a fallacy to say that because Frege is an expert and believes Basic Law V is true, then it is true. What Frege believes is not what gives the truth value to the statement, and it is of course possible for experts to be wrong.

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    It took me several reads to decide I agreed with what you've got here. The main struggle was the structure of the first paragraph. (I personally think the point about the fallacy itself could be made clearer -- which I will try myself). – virmaior Jun 6 '18 at 5:23
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    @virmaior I was drunk when I wrote this, I have been meaning to come back and restructure it. The main point I want to stress is that saying "the reason something is true is because an expert said so" is fallacious. – Not_Here Jun 6 '18 at 5:30

There's nothing wrong with referring to experts in the field to support your reasoning. In fact it's how our society builds knowledge. The appeal to authority fallacy occurs when the expertise of the cited "authority" is not relevant. For example a commonly cited "authority" that denies anthropogenic climate change is William Happer, but Dr. Happer studies physics, not climate, so it is fallacious to suggest that his thoughts have merit just because he's a scientist.


Aristotle was a proponent of the view that heavier bodies fall faster than lighter bodies.

His view was taken up and propagated again by "philosophers" of other generations and societies; all without checking whether this was actually the case. One simply did not question Aristotle, because he was an authority.

This, in a nutshell is the problems with appeals to authority - it does away with the need for re-validation. It becomes especially problematic when views become dogmas and questioning dogma results in getting your head chopped off. Happily, this tends not to happen anymore, which is not to say that academia is not littered with political reprisals triggered by challenging entrenched views.

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