Logical Fallacies

Appeal to Ignorance

This fallacy occurs when you argue that your conclusion must be true, because there is no evidence against it. This fallacy wrongly shifts the burden of proof away from the one making the claim.

Ad Hominem

(Attacking the person): This fallacy occurs when, instead of addressing someone's argument or position, you irrelevantly attack the person or some aspect of the person who is making the argument. The fallacious attack can also be direct to membership in a group or institution.

Confusion of Necessary with a Sufficient Condition

A causal fallacy you commit this fallacy when you assume that a necessary condition of an event is sufficient for the event to occur. A necessary condition is a condition that must be present for an event to occur. A sufficient condition is a condition or set of conditions that will produce the event. A necessary condition must be there, but it alone does not provide sufficient cause for the occurrence of the event. Only the sufficient grounds can do this. In other words, all of the necessary elements must be there.

Inconsistency

A person commits the fallacy of inconsistency when he or she makes contradictory claims.

Two Wrongs

If you try to justify an act/belief by pointing out in others a similar act/belief, you are committing the fallacy of "two wrongs make a right." This fallacy can occur by suggesting "if others are doing it, I can too" (common practice). Another form of the fallacy occurs when you dismiss a criticism of your action/belief, because your critic is acting/believing in a similar way (you do it, too).

Slippery Slope

In a slippery slope argument, a course of action is rejected because, with little or no evidence, one insists that it will lead to a chain reaction resulting in an undesirable end or ends. The slippery slope involves an acceptance of a succession of events without direct evidence that this course of events will happen.

Begging the Question

The fallacy of begging the question occurs when an argument's premises assume the truth of the conclusion, instead of supporting it. In other words, you assume without proof the stand/position, or a significant part of the stand, that is in question. Begging the question is also called arguing in a circle.

Equivocation

The fallacy of equivocation occurs when a key term or phrase in an argument is used in an ambiguous way, with one meaning in one portion of the argument and then another meaning in another portion of the argument.

Irrelevant Authority

The fallacy of irrelevant authority is committed when you accept without proper support for his or her alleged authority, a person's claim or proposition as true. Alleged authorities should only be used when the authority is reporting on his or her field of expertise, the authority is reporting on facts about which there is some agreement in his or her field, and you have reason to believe he or she can be trusted. Alleged authorities can be individuals or groups. The attempt to appeal to the majority or the masses is a form of irrelevant authority. The attempt to appeal to an elite or select group is a form of irrelevant authority.

Is Ought

The is-ought fallacy occurs when the assumption is made that because things are a certain way, they should be that way. It can also consist of the assumption that because something is not now occurring, this means it should not occur. In effect, this fallacy asserts that the status quo should be maintained simply for its own sake. It seeks to make a value of a fact or to derive a moral imperative from the description of a state of affairs.

Ought Is

The ought-is fallacy occurs when you assume that the way you want things to be is the way they are. This is also called wishful thinking. Wishful thinking is believing what you want to be true no matter the evidence or without evidence at all, or assuming something is not true, because you do not want it to be so.

Faulty Analogy

This fallacy consists in assuming that because two things are alike in one or more respects, they are necessarily alike in some other respect.

Red Herring

This fallacy consists in diverting attention from the real issue by focusing instead on an issue having only a surface relevance to the first.

Questionable Cause

This fallacy occurs when a causal connection is assumed without proof. All too often claims to a causal connection are based on a mere correlation. The occurrence of one event after the other or the occurrence of events simultaneously is not proof of a causal connection

Unwarranted Generalization

This fallacy occurs when we we make a generalization on the basis of insufficient evidence. This may occur when we rely on too small of a sample or an unrepresentative sample to support the generalization.

Straw Person

This fallacy occurs when, in attempting to refute another person's argument, you address only a weak or distorted version of it. Straw person is the misrepresentation of an opponent's position or a competitor's product to tout one's own argument or product as superior. This fallacy occurs when the weakest version of an argument is attacked while stronger ones are ignored.

False Dilemma

When you reason from an either-or position and you haven't considered all relevant possibilities you commit the fallacy of false dilemma.