Logic and Logical Fallacies

Flashcards on Logic and Logical Fallacies

Logic

The study of correct reasoning, the laws of thought.

Argument

Premises that lead to a logical conclusion, typically in the form of a syllogism.

Deductive Reasoning

Structuring an argument so that if the premises are true, the conclusion must be true.

Inductive Reasoning

Inferences that draw a reasonable, but not necessarily true, conclusion from premises, focusing on argument, fallacies, and reasoning.

Valid Argument

An argument with a correct form or structure, regardless of the truth of the statements.

Form, not the correctness or truth

Sound Argument

An argument that is valid and has true premises, leading to a necessarily true conclusion.

Content/truth of the argument

Ad Hominem Fallacy

Replacing logical arguments with an attack usually about the opponent, distracting from the actual argument.

Person making the argument is irrelevant so the argument is irrelevant too

Strawman Argument

Creating an easier version of the opponent's argument and then attacking it instead of the real one.

Real goal should be to “steelman”

Tu Quoque Fallacy

Distracting from the argument by pointing out hypocrisy in the opponent instead of addressing the argument itself.

“You also do x”

Appeal to hypocrisy

Red Herring Fallacy

Distraction from the argument by raising a sentiment that seems relevant but is not.

Appeal to Authority Fallacy

Asserting a claim is true by relying on an authority figure.

False Dilemma Fallacy

Fallaciously limiting the options to two options when there could be more options to choose from.

Slippery Slope Fallacy

Moving from a seemingly benign starting point and going to an unsupported extreme.

Circular Reasoning Fallacy

Assuming what you are trying to prove in a premise (begging the question).

Genetic Fallacy

Basing an argument solely on the origins of something rather than its actual merits.

Origins of something tell us little about what it would be today

Naturalistic Fallacy

Assuming something is good or right because it is natural.

Burden of Proof Fallacy

Failing to support one's own assertion and challenging others to disprove it; shifting the burden of proof.

• The person making the claim always has the burden to prove it up so… this way would never be ok because it is shifting the burden of proof

Post Hoc Ergo Propter Hoc Fallacy

Assuming that because one event followed another, the first event caused the second.

Hasty Generalization Fallacy

A grossly oversimplified conclusion that is not supported by sufficient evidence.

Whole/Part Fallacy

Assuming that parts or members of a whole will have the same properties as the whole.

Non Sequitur Fallacy

When the conclusion does not logically follow from the premises.

False Analogy

Drawing an analogy between two things that are not alike in the relevant respects.

Equivocation Fallacy

Using a word, phrase, or sentence deliberately to confuse or mislead by sounding like it's saying one thing but actually saying something else.

Appeal to Emotion Fallacy

Manipulation of the recipient's emotions to win the argument instead of addressing the actual argument.

Fallacy Fallacy

Just because an opponent's argument has a fallacy doesn’t necessarily mean that their conclusion is wrong.

Categorical Syllogism

1. All birds have feathers

2. All robins are birds

   • Therefore, all robins have feathers

Conditional (hypothetical) Syllogism

1. If it rains, then the ground gets wet

2. It is raining

   • Therefore, the ground is getting wet

Disjunctive Syllogism

1. Either the light is on or the power is out

2. The light is not on

   • Therefore, the power is out