Ryerson University SSH 105 Critical Thinking Mistakes

Personalizing Reasons

It is a mistake to personalize reasons by treating them as if they belonged to someone. Epistemic reasons are universal and objective, but personalizing reasons obscures this fact and allows emotion to get in the way.

Appeal to Relativism

It is a mistake to just assume that truth is relative without powerful reasons to. It is best to assume that Realism is the appropriate attitude for most topics, because in most topics, truth is the same for everyone.

Appeal to Emotion

It is a mistake to base our beliefs only on our emotions. For a belief to be justified enough for knowledge, it must be based on good epistemic reasons - but how a belief makes us feel does not relate to whether it is true or if there is evidence for it.

Privileging Available Evidence

It is a mistake to assume that evidence that we currently have is better than evidence we might later collect. If one did collect more evidence, this evidence could override or undermine the evidence we currently have - so current evidence may not be true. A good critical thinker keeps an open mind.

Appeal to Tradition

It is a mistake to believe something just because that belief is traditional, i.e. that people have historically always had that belief. This is not an epistemic reason, and tradition may not always be based in truth.

False Definition

It is a mistake for a definition to be too broad or too narrow, or both. This would make the definition technically false. In critical thinking, we are concerned with finding the truth. A false definition could include or exclude factors that could be important to the argument.

Equivocation

To equivocate is to use words in different senses without realizing it. This is a mistake because if two parties are using words in different senses, they are actually arguing over different premises and conclusions and so the argument is not productive. Or, if one party uses the word in multiple senses and the word must be one thing to maintain true premises but another to maintain validity, then the argument cannot be sound.

Straw Man Fallacy

It is a mistake to distort or misrepresent another's argument when criticizing it. It is rude and not productive because you cannot work from the other's actual argument to get to the truth together. Good critical thinkers are accurate and charitable with others' arguments, so that everyone may build off of them.

Post-hoc Fallacy

It is a mistake to believe that one thing is the effect of another just because that thing happened after. While all effects do follow its cause, this order of events is not sufficient to indicate a causal link.

Appeal to Ignorance

It is a mistake to believe something just because you have no evidence that is is false. If one collected even more evidence, it could possibly show that the belief is false (e.g., by overriding or undermining it or showing another possibility). Good critical thinkers must look for evidence when one can.

Unacceptable Testimony

It is a mistake to accept testimony from a witness if the topic is inappropriate, the witness is not properly trained or not properly informed, or if the witness is biased. When using testimonies for evidence, one bust consult an appropriate, trained, and informed expert without biases.

Ad Hominem Fallacy

It is a mistake to believe a piece of testimony is false just because the witness is unreliable or biased. Even if evidence is undermined, it can still be true. When making this mistake, one is criticizing the source of the testimony instead of the testimony itself and ignoring the argument itself.

Bad Question

It is a mistake to ask a question that is ambiguous, contains charged or slanted words, or that hides a controversial presupposition. These questions obscure the actual beliefs that the person answering the question holds, because they influence the answer. Good critical thinkers ask open-ended questions.

False Disjunction

It is a mistake to reason with a false disjunction, because an argument with a false premise is not sound. If the argument reasons by denying a disjunct, then the conclusion might be false as well.

Denying the Antecedent

It is a mistake to believe that a consequent Q did not occur just because an antecedent P did not. P is sufficient for Q, but P is not necessary for Q, so this argument is sometimes invalid. Something else could have caused Q.

Affirming the Consequent

It is a mistake to believe that an antecedent P occurred just because a consequent Q occurred. This argument is not always valid, because P is sufficient for Q, but not necessary. Q could have been caused by something else.

Affirming a Disjunct

It is a mistake to conclude that one disjunct is false just because the other one is true. This is mistake because some disjunctions may be inclusive (i.e., both disjuncts may be true), so this is not always valid. Reasoning by this means there's a missing premise: that the disjunction is exclusive (which you must add to make the argument valid only if you have good reason to believe the disjunction is exclusive).

Red Herring Fallacy

It is a mistake to raise irrelevant matters when criticizing someone's beliefs or reasons. This is a mistake because it distracts from working towards the truth together, which is rude

Hasty Generalization

It is a mistake to rely on an unrepresentative sample when reasoning using samples. This is a mistake because the analogical premise is then false, meaning the argument is not sound. There was not enough care to make sure that the sample represents the greater population that the argument concerns.

False Analogy Fallacy

It is a mistake when reasoning by perfect analogy for the analogical premise to be false, because the argument would not be sound. Many pairs of things are alike in many ways, but a perfect analogy requires that the two analogues be exactly alike in all respects relevant to the relevant property.

Slippery Slope Fallacy

It is a mistake to reason with a false causal conditional that is extreme in nature. If the argument includes such a false premise, then it could not be sound.