Critical Thinking Lecture 12 Causal Arguments By David Kelsey

Causal Arguments Causal claim: states or suggests the presence of causation. Examples: A causal argument has as its conclusion a causal claim. A cause is an event, person, place or thing X without which some other event, person, place or thing Y, X’s effect, would not occur, exist, etc. A cause necessitates its effect such that without the cause, the effect would not occur. Causes can’t just be correlations though. Causal powers

Post Hoc Fallacy Post Hoc Fallacy: When one thinks that just because X is followed by Y this must mean that X causes Y. Post Hoc is short for Post Hoc, Ergo Propter Hoc which translates: The mistake is Thinking Correlation entails causation: Accidental correlation: this is a mistake because X could play no role in Y’s coming to be. X could merely be accidentally correlated with the occurrence of Y. 3 pennies example: Other possibilities besides X causing Y or X and Y being accidentally correlated:

Hypotheses Hypothesis: a supposition offered as a starting point for further investigation. When hypothesizing you are conjecturing, I.e. making a guess about some way the world is. How do we test a hypothesis? Look for counterexamples to it. What is a Counterexample? A counterexample to: Vitamin C cures colds

Relevant difference reasoning If some effect, Y, occurs in one situation & Y doesn’t occur in other situations similar we can try to find something that is different about this situation, I.e. X. We then suspect this difference X is the cause of Y. To find X, simply look for the differences between this situation and those situations that are similar but in which Y doesn’t occur. Use relevant difference reasoning when:

Which difference is relevant? Question: how do you know which is the relevant difference? Engine overheating:

Examples of Relevant difference reasoning Headaches: Post Office:

Common Thread Reasoning When do we use this kind of reasoning? Look for a common thread: some event, person, place or thing that is common to all the occurrences of the effect. Mosquito example:

Common mistakes in informal causal reasoning 1.) We can overlook alternative common threads or differences: If one difference or thread seems particularly relevant, don’t overlook others as you may miss the real cause in doing so. Example: 2.) We can focus on irrelevant differences or common threads: To know that a difference or thread is relevant you must have some knowledge of the situation, its causes and its effects.

3 more mistakes 3.) We can overlook the possibility that causation is the reverse of what has been asserted: Climbing a rope: 4.) We can overlook the possibility that the asserted cause and effect are both the effects of some third underlying cause: The leaves turning yellow: 5.) We can fail to consider the possibility of coincidence: The cancer example:

Doubtful causal claims 1. Appeal to Anecdotal evidence: watch out for a causal claim when the evidence is one or two cases only. Smoking doesn’t cause cancer: To show smoking doesn’t cause cancer we need to show that even if everyone smoked, the cancer rate would not increase. Can you do this with 1 piece of evidence though? 2. Circularity: The cause cannot merely restate the effect for if so we haven’t learned anything new. Insomnia example: 3. Excessive Vagueness: if a causal claim is too vague we won’t know exactly how it is to be tested. Bad Karma example:

Doubtful causal claims #2 4. Nontestability: we can’t have a causal claim for which testing is isn’t possible. Aids example: 5. Unnecessary assumptions: why needn’t make any unnecessary assumptions in asserting a causal claim? Déjà vu example: 6. Conflict with well-established theory: as a general rule, we don’t really want our causal claims to conflict with our theories. We can have theoretical advances, but… Height example:

Causal Explanations vs. Arguments A causal explanation is an explanation of the cause of something. Explanations vs. Arguments: while causal explanations can look superficially like arguments, explanations assert cause and effect while arguments try to prove that something is the case. Explaining causes: When we try to justify or defend or excuse something we or someone else did, we sometimes explain its causes. Bread example: But not every attempt to explain behavior is an attempt to excuse it: One might be simply trying to offer an explanation without any sympathy at all for the actions being explained. Nazi Germany example: