Any L-argument that supports a conclusion based on the authority, or reliability, of the source from which it came is inductive Argument from Authority/from a Source.

Arguing from a source generally has the pattern, at least implicitly:

X asserts p
X is a reliable source
Therefore, p is probably true (credible)

This is generally the sort of argument you make when you cite your sources in a research paper.

This sort of argument can include citing books, articles, speakers, street signs, honest eyewitnesses, the medical community, authoritative web pages, etc.

For example, you might correct someone, “The Vomitorium was not a room where ancient Romans went to throw up.” Then they ask, “How do you know (what support do you have)?” If you say you read it in an article in Scientific American (click for article), you are arguing in support of your claim by citing a reliable source.

This sort of argument depends on crucial skills of assessing the credibility of various sources of information.

One the one hand, this plays out in a more “academic“ style akin to writing research papers.

On the other hand, this plays out every day in the social skills of assessing where one can find reliable information on any sort of topic.

This is INDUCTIVE argument, because no source is perfect. But remember, don’t let the perfect be the enemy of the good!!!

Just because no source is perfect does NOT mean that you should disregard how good a source is. Constantly work to find the bestsources, and give more weight to better sources when comparing different sources.

Appropriate Appeal to Qualified Authority = Good Research, logically relevant to your topic.

KNOW YOUR SOURCE!!!
Excellent sources should be open, transparent, with nothing to hide. Excellent sources include:

The best news organizations. Newspapers have a history of being the best sources for original reporting; television and radio never have been as thorough. Here’s a recommended ranking of news sources. And one more, from Forbes.
Fact-checking web sites such as Factcheck.org and Politifact.com., and Media Bias Fact Check.com You can also fact-check images to see if they’ve been altered by doing a reverse image search on Google or TinEye.com, for example.
Non-partisan (not affiliated with a political party) data collecting agencies, such as the Census Bureau, Federal Trade Commission, Centers for Disease Control and Prevention, the Government Accounting Office, etc.
Scholarly publications, academic journals, research institutes.
Textbooks, non-fiction books from established publishers.
Eyewitnesses who can be impartial and not subject to distorting influences.
Wikipedia is a useful tool, but should not be cited as an original source of information. It is basically second-hand information.
Consumer Reports is a great non profit source for impartial, objective reviews of a large array of products.

Recommended: The SIFT method for checking sources. https://bbc.com/future/article/20240509-the-sift-strategy-a-four-step-method-for-spotting-misinformation

https://youtu.be/q1k8rcYUmbQ

The imposters

HEARSAY, 2nd-, 3rd-, 4th-hand information (gossip, rumors, etc.) is not reliable. It is usually easy enough to track things down to the original source.

UNQUALIFIED SOURCES. Unqualified sources are useless, making it a false appeal to authority. This amounts to, “Some guy told me...” And “I saw it on a social media post” has equally low status.
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Extraordinary claims require extraordinary evidence, so no single person or group is qualified in a way that we should just “take their word for it.” (For criminal prosecution, it is very unfortunate to rely only on a single witness, with no corroborating material evidence. Imagine how easily you could be prosecuted for a crime you didn’t commit with that sort of evidence!) Conspiracy Theories are extraordinary claims, often supported with nothing more than an argument that they are possibly true.
Mistaken (but sincere) sources. Unqualified sources can be sincerely mistaken rather than lying. They might sincerely believe what they are telling you, but you have to ask whether they are really in a position to know. Ask whether their perception, memory, or judgment could have been compromised, for example. (Remember how Jennifer Thompson’s memory of her rapist was distorted by the line-up process, and how the eyewitness’s testimony in 12 Angry Men was weakened because of the marks on her nose.)
Outside their area. Sources can be highly qualified in one area, but sometimes make claims outside their area of expertise. In that case, their opinion has no more weight than any one else’s, making it a false appeal to authority.
Non-Expertise Topics. On some issues, such as the meaning of life, there is no authority we should submit to, but at best sage advice, to be thoughtfully considered.

CHERRY-PICKED SOURCE. Cherry-picked sources are no better than a biased sample in inductive generalization, making it a false appeal to authority. It’s possible to find someone with impressive looking credentials to support almost any claim. It is always much stronger to argue from a broad consensus, agreement among a large majority, of experts.

BIASED SOURCE. Avoid a likely biased, co-opted or lying source

People who have something to gain or lose based on the truth of a certain claim are not impartialsources. They are biased, either consciously or unconsciously, making it a false appeal to authority.
Paid endorsements are one type of bias — the endorser gains financially by supporting a product or candidate, so we have no good reason to believe what they say. They might not even believe it themselves.
Some sources might be pressured(co-opted) into saying something that’s not true, making it a false appeal to authority.

MISQUOTED SOURCE. Beware of someone using a misquoted source, or quoting out of context, to back up their position. This is an easy, but totally dishonest and childish game to play, making it a false appeal to authority.

As David Hume writes, “We entertain a suspicion concerning any matter of fact, when the witnesses contradict each other; when they are but few, or of a doubtful character; when they have an interest in what they affirm; when they deliver their testimony with hesitation, or on the contrary, with too violent asseverations. There are many other particulars of the same kind, which may diminish or destroy the force of any argument, derived from human testimony.”

The scarecrow fallacy

In Argument from a Source, we saw the mistake of supporting a claim by misquoting or misrepresenting a source.

Another common mistake is to misquote or misrepresent someone else’s position or argument while attacking it.

This is called the Scarecrow (or Straw Man) Fallacy. The idea behind the name is that, instead of addressing an actual person’s position, you address an imitation (fake version) of the person.

It is one version of committing a fallacy while interacting with someone else’s position or argument.

For example: arguing against someone who supports lowering the drinking age to 18 by claiming (misrepresenting) that they support letting children drink alcohol.

l.

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You shouldn’t attack scarecrows!!

Appeal to the people

Citing what “the People” say is not a strong source. This mistake is the fallacy traditionally called Appeal to the People. This is sometimes called the Bandwagon Fallacy, mindlessly going along with what you hear other people saying or doing. Citing social media posts, even viral posts, is the latest version of this age-old mistake.

For example, “I had so many people tell me COVID-19 was a fake disease.”
For example, saying “Of course Vikings had horns on their helmets! Just ask anybody,” is not a good argument. “Everybody knows the color red makes bulls angry.” It is widely believed, but nobody really knows it. Bulls are partially color blind and can’t distinguish red.
Check Snopes.com for fact-checking thousands of things that “people say.”
This fallacy also includes to what “the people” have said or did over history. This is the so-called Appeal to Tradition, and it is weak! People down through history have done and believed all sorts of stupid things. Consider bloodletting, for example!
[Beware also of the opposite of the Appeal to Tradition, The Shiny-New-Thing Effect, mindlessly hopping on the bandwagon for something just because it’s new and different. Always ask whether it is actually better than what’s came before it.]

:-/

For a good rundown of several widely-believed but nonetheless false claims, see: https://www.geekwrapped.com/myth-infographic

and https://www.informationisbeautiful.net/visualizations/common-mythconceptions/

Evaluating a source vs. ad hominem fallacy, a.k.a. attacking the person

As we’ve seen, to make an Argument from a Source, you must evaluate your source. You should nottrust unqualified, biased, cherry-picked, or misrepresented sources. You should not cite “people say ...” as a source (Bandwagon Fallacy, Appeal to the People)

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Unfortunately, many people apply the mindset of evaluating sources to evaluating someone’s argument.

Rejecting someone’s argument based only on criticisms of the person giving the argument commits the AD HOMINEM FALLACY.

For this reason, it is very important to distinguish people simply making assertions, giving testimony (saying in effect “take my word for it”) from people citing independent evidence in an argument!

“Ad Hominem” is Latin for “to the person,” and it refers to the mistake of directing criticism to the person making an argument rather than toward the argument itself.

This differs from the Straw Man (or Scarecrow) Fallacy, which fails to address an opposing argument by misrepresenting it, addressing a fake.
Ad Hominem fails to address an opposing argument because it directs criticism to the person giving the argument.

ALWAYS REMEMBER, An argument stands or falls on its own merits, regardless of the character or motives of the person presenting the argument!!!

BEWARE! People often apply the term ‘Ad Hominem’ to criticisms of people that are not fallacies. NOT every personal attack is the Fallacy of Ad Hominem. If you criticize another person and support it with strong evidence, that is not the Fallacy of Ad Hominem.

AD HOMINEM - personal attack

Rejecting an argument based on an irrelevant attack of the arguer’s character is the fallacy of Ad Hominem-Personal Attack. The arguer’s character is logically irrelevant to the quality of the argument itself.

Bad people can give good arguments, and
Good people can give bad arguments!

As a humorous example:
Stephen Colbert: Have you ever done drugs?
Nadelmann: Well...I...Stephen...I have smoked the occasional joint when I'm ---
Colbert: So YOU are a criminal, and none of your arguments have validity now.

Correct Argument, by contrast: If someone is NOT giving an argument but only making a claim/giving testimony/saying “take my word for it,” it is relevant to assess the person's character in deciding whether to “take their word for it.” If you know, for example, that they have the character of a well-known liar and manipulator, you’d be a fool to take their word for it!

AD HOMINEM - attacking the motive

Some books call this “Ad Hominem-circumstantial”

This fallacy consists in rejecting an argument based on irrelevant criticism of the arguer’s motivation for giving the argument (usually claiming the argument is motivated by self-interest. — they stand to benefit (in their circumstances) if the conclusion is true). The arguer’s motivation is logically irrelevant to the quality of the argument itself.
In fact, self-interest can be a powerful motivator leading someone to construct very good arguments!!

(Sometimes you see the reverse – a person uncritically accepting an argument just because it goes against the narrow self-interest of the person giving it. I don’t know of a good name for that one.)

Correct Argument, by contrast: If someone is NOT giving an argument but only making a claim/giving testimony, it is relevant to consider whether they have a motive to lie or distort the facts before you “take their word for it.”

AD HOMINEM - Look who’s talking

Some books use the Latin phrase “tu quoque.” There’s no need for you to remember that Latin name.

Rejecting an argument because the arguer is being hypocritical (inconsistent in their behavior — failing to practice what they preach) commits this fallacy. Whether the arguer follows their own conclusion is logically irrelevant to the quality of the argument.

Someone can give a perfectly good argument for brushing and flossing daily, but if they don’t do it themselves, they are the ones who will go under the dentist’s drill!! That definitely does not mean they made a bad argument (it just makes their rotting teeth quite ironic).

See, for example: “Fifa president Gianni Infantino accuses West of 'hypocrisy'” https://www.bbc.com/sport/football/63687412Links to an external site.

[Of course, if the argument itself contains a logically inconsistent claims, that is a relevant criticism.]

Correct Argument, by contrast: If someone is NOT giving an argument but only making a claim/giving testimony, it is relevant to note inconsistency. The fact that they don't “practice what they preach,” or that they made a contrary claim elsewhere, undermines their testimony.

The case of expert testimony

Typically, we determine whether to accept an expert’s testimony based only on their qualifications, making most character issues and whether they follow their own advice logically irrelevant (as if they were giving arguments). Citing well-qualified experts counts as a strong Argument from a Source.

However, it can be relevant to question whether they are notorious liars, guilty of breaching professional ethics, or have a motive to (consciously or unconsciously) misrepresent the facts. Any Argument from a Source should beware of potential bias.

Thus, it is always a good idea to get testimony or advice from several independent experts. As they say, “Get a 2nd (and 3rd and 4th) opinion!” This minimizes the chances that one individual’s bias or mistakes would undermine the claim they all independently verify