Our Logic is Better Than Yours
Have you ever heard an argument that didn’t seem right? Maybe you disagreed with the speaker’s logic but couldn’t put your finger on the problem. You likely encountered a “logical fallacy,” which is an occurrence of bad or incorrect reasoning. Explore this site to learn more about all the informal fallacies you may encounter! Once you understand the informal fallacies, you'll be able to sniff them out and utilize sound logic to discredit them.
Meet the Fallacies
Fallacies of Relevance
Fallacies of relevance have premises that do not “bear upon” the truth of the conclusions. In other words, they introduce an irrelevancy into the argument.
Ad Fontem Arguments
(Arguments against the Source): The Latin phrase ad fontem is literally translated as “to or from the fountain.” Ad fontem arguments are a subgroup of the fallacies of relevance, and they consist of arguments that focus on discrediting the source of the argument instead of analyzing the argument itself.
Ad hominem abusive arguments are derived from the Latin phrase ad hominem, which is literally translated “to the man” or “against the man.” Ad hominem abusive arguments are the most obvious of all personal attacks and are committed when a speaker attempts to avoid the issue by insulting an opponent with abusive language rather than focusing on the merits of the argument under consideration.
Ad hominem circumstantial arguments are a kind of ad fontem argument. The speaker attacks his opponent by saying or implying that his rival’s circumstances make his argument untrustworthy.
The Latin phrase tu quoque means “you too.” The tu quoque fallacy is a type of ad fontem argument. The person committing this fallacy assumes that his rival’s recommendation should be discounted because he does not always follow it himself.
This is a very tricky type of ad fontem argument. A genetic fallacy is an argument that states that an idea or belief should be discounted simply because of its source or origin.
Appeal to Emotion
All fallacies appeal to our emotions in some form, but these kinds of fallacies do so in particularly irrelevant and obvious ways. Appeal to Emotion arguments are a subgroup of the fallacies of relevance and consist of arguments that focus on emotional manipulation rather than the issue at hand.
The Latin phrase ad baculum means “to the stick.” The appeal to fear fallacy is one kind of appeal to emotion. This fallacy can be easily confused with an actual physical threat of impending harm. A person committing the appeal to fear fallacy references the potential for bad consequences that might occur if the person to whom they are speaking does not agree with them. In this way, the speaker appeals to the audience’s fear.
My political views align the most with the Libertarian political platforms. However, I realize the two larger political parties (Republican and Democrat) are often the more successful here in the United States. If I’m registered as Libertarian, then I won’t have a chance to impact the primary election tickets for either of the larger parties, one of which will eventually be the winner. That makes me afraid that I’m not influencing the candidate pool, so I’m going to register as a member for one of the larger parties so I can impact the candidate choices in the primary election.
The Latin phrase ad misericordiam means “to pity.” This fallacy is an appeal to the emotion of pity. Using this type of argument, the speaker tries to convince others of his point of view by making them feel sorry for him or for other people.
Ad populum is Latin for “to the people.” Ad populum is an appeal to emotion fallacy that tries to make up for a lack of solid evidence and sound reason by appealing to the emotions of the crowd or to the “common man.”
This fallacy is an appeal to a sense of elitism or to those of “discriminating taste.” The speaker might appeal to a person’s desire to be seen as someone who appreciates fine things, as someone who is part of a special group, or as someone who is set apart and distinctive so as to be considered extraordinary or better than others.
A type of Appeal to Illegitimate Authority fallacy that suggests the listener should accept the opinions of one who has no expertise in the topic being discussed.
A type of Chronological Fallacy which holds that a traditional belief, practice, or institution is good or bad simply because it is old.
A type of Chronological Fallacy which holds that a traditional belief, practice, or institution is good or bad simply because it is new.
Red Herring arguments are a subgroup of the fallacies of relevance and include types of proofs that don’t attack the source or play on our emotions but nevertheless introduce points that are irrelevant to the issue under consideration.
The Appeal to Ignorance fallacy is a kind of red herring fallacy that occurs when a speaker attempts to suggest that “if you can’t prove me wrong, I must be right.” This fallacy makes the mistake of saying that because a proposition cannot be proven false, it must therefore be true or likely.
The irrelevant goals or functions fallacy is a kind of red herring fallacy. A speaker using this fallacy argues that a practice or policy fails to achieve some goal or function when, in fact, it was never intended to achieve that goal or function. The speaker argues that because of this supposed “failure,” the practice or policy is not acceptable.
A very common red herring argument, the straw man fallacy is an attempt to disprove an opponent’s beliefs by reframing his argument and presenting his beliefs in an overly simplistic, unfair, and inaccurate light. We call this kind of argument a “straw man” fallacy because it reminds us of a scarecrow. On the surface, it appears to resemble the opponent’s position, but in reality is a flimsy representation of the real argument.
Fallacies of Presumption
Fallacies that make unwarranted assumptions about either the data or the nature of a reasonable argument.
Fallacies of Presupposition
Fallacies of Presupposition are a subcategory of Fallacies of Presumption. They are derived from the verb “pre-suppose” and are the hidden, predetermined ideas or assumptions that an individual brings to an argument. A presupposition is an assumption that is hidden and that we unknowingly bring with us before we ever encounter any evidence (some might call these our biases).
A type of Begging the Question fallacy that creates a circular argument by presenting a conclusion while trying to convince the listener they are being given a real premise that leads to this conclusion.
A type of Begging the Question fallacy which asks a question that already assumes what the speaker wants others to accept without providing any evidence.
Prosecutor: Where did you hide the gun after you fired it at Mr. Johnson?
Defendant: I didn’t hide it anywhere!
Prosecutor: So you still have it!
Defendant: No, I don’t have any guns!
Prosecutor: But you just said you didn’t hide it, so you must have it. May I remind you that you are under oath to tell the truth?
A type of Begging the Question fallacy that is also called a question-begging definition. It occurs when a presenter tries to define the terms of his argument in a way that assumes a conclusion that he is obligated to prove.
A type of Begging the Question fallacy which is also called the question-begging epithet (epithet is another name for label) and occurs when someone labels another person or thing in a way that assumes a conclusion without offering any evidence.
A kind of fallacy of presupposition, the bifurcation fallacy attempts to frame the debate in such a way that makes only two options possible when, in fact, other possibilities may exist.
Isabela Island, one of the islands which makes up the Galapagos Islands, has a problem with the indigenous giant tortoise population being at odds with the introduction of goats into the ecosystem. Clearly, we have to sacrifice one species or the other. I suggest we eradicate the thriving goat population in order to preserve the giant tortoise population on the island.
One of the most common fallacies of presupposition, the fallacy of moderation is based on the assumption that the correct answer is always the middle ground or a compromise between two extremes.
A fallacy of presupposition that assumes that just because something is a certain way, it ought to be that way.
The fallacy of division is another kind of fallacy of presupposition. The fallacy of division is an argument based on the assumption that individual parts of a collective whole will necessarily have all the characteristics of the collective whole.
The fallacy of composition is another type of fallacy of presupposition. The fallacy of composition is an argument based on the assumption that a collective whole will necessarily share all of the characteristics of its individual pieces.
Fallacies of Induction
Fallacies of Induction are a subcategory of Fallacies of Presumption. These fallacies make unnecessary (or unwarranted) assumptions about empirical data or they fail to use proper inductive reasoning from that data. These fallacies are often hidden behind seemingly concrete facts and data.
The hasty generalization fallacy is another kind of fallacy of induction. This fallacy makes a generalization (that may or may not be true) about a class of things on the basis of too few examples or not enough evidence.
The sweeping generalization fallacy is another kind of fallacy of induction. This fallacy takes a generalization (that may or may not be true) and extends it to cases that are legitimate exceptions to it.
A form of False Cause fallacy that is Latin for “after this, therefore because of this.” It simply means that people are prone to think that because one event follows another event, the first event must have caused the following event.
A type of False Cause fallacy which assumes that because something cannot occur without a certain factor or condition being present, it will necessarily occur if that factor is present.
A type of False Cause fallacy in which a causal relationship exists between two elements, and an argument is based on the misunderstanding that the effect is the cause and the cause is the effect.
A type of False Cause fallacy that occurs when the speaker believes that one thing is causing another thing, when in fact a third factor is causing both.
Perhaps the most data-driven fallacy of induction, the fake precision fallacy uses numbers or statistics in a way that is too precise to be justified by the situation.
Fallacies of Clarity
Arguments that fail because they contain words, phrases, or syntax that distort or cloud their meanings.
A fallacy of clarity that fails because a key term upon which the argument rests is employed more than once with several different meanings.
School District Board Member: I don’t see any reason why we should listen to the superintendent of schools on the textbook issue. We need to hear from someone who has some authority in the field of education. Our superintendent doesn’t even have the authority to keep the students in line. Nobody respects her orders.
C.S. Lewis is misquoted in María’s comment: “I know a lot of folks really admire renowned author and theologian C.S. Lewis. But I’ve read some of his writings and he said, ‘Do not waste time bothering whether you ‘love’ your neighbor…’ Clearly, he’s a selfish, old erudite and I’m not inclined to take life lessons from such a person.”
A fallacy of clarity that makes a linguistic distinction between two things that are in reality not distinct from each other