Concise Guide to Critical Thinking Chapter 7

Causal claim—A statement about the causes of things Causal claim—A statement about the causes of things. Causal argument—An inductive argument whose conclusion contains a causal claim.

Mill’s Methods Method of Agreement: If two or more occurrences of a phenomenon have only one relevant factor in common, that factor must be the cause. Method of Difference: The relevant factor present when a phenomenon occurs, and absent when the phenomenon does not occur, must be the cause.

Joint Method of Agreement and Difference Mill’s Methods Joint Method of Agreement and Difference The likely cause is the one isolated when you: Identify the relevant factors common to occurrences of the phenomenon. Discard any of these that are present even when there are no occurrences.

Method of Concomitant Variation Mill’s Methods Method of Concomitant Variation When two events are correlated—when one varies in close connection with the other—they are probably causally related.

Mill’s Methods Caution: Correlation does not always mean that a causal relationship is present. A correlation could just be a coincidence. For example: An increase in home PC sales is correlated with a rise in the incidence of AIDS in Africa, but this doesn’t mean that one is in any way causally linked with the other.

Causal Confusions Misidentifying Relevant Factors Mishandling Multiple Factors Being Misled by Coincidence Confusing Cause with Temporal Order Confusing Cause and Effect

Causal Confusions Misidentifying Relevant Factors Your ability to identify relevant factors depends mostly on your background knowledge—what you know about the kinds of conditions that could produce the occurrences in which you’re interested. Lack of background knowledge might lead you to dismiss or ignore relevant factors or to assume that irrelevant factors must play a role.

Causal Confusions The rule of thumb: People are especially prone to “it can’t be just coincidence” thinking because they misjudge the probabilities involved. The rule of thumb: Don’t assume that a causal connection exists unless you have good reason for doing so.

The truth about coincidences: Causal Confusions The truth about coincidences: Given the ordinary laws of statistics, incredible coincidences are common and must occur. Any event, even one that seems shockingly improbable, is actually very probable over the long haul. Given enough opportunities to occur, an “unlikely” event is virtually certain to happen to someone.

Causal Confusions The fallacy of post hoc, ergo propter hoc: The fallacy of reasoning that just because B followed A, A must have caused B.

Instances of post hoc, ergo propter hoc? Causal Confusions Instances of post hoc, ergo propter hoc? Argument 1 After the training for police officers was enhanced, violent crime in the city decreased by 10 percent. So enhanced training caused the decline in violent crime. Argument 2 An hour after Julio drank the cola, his headache went away. The cola cured his headache.

Necessary and Sufficient Conditions Necessary condition—A condition for the occurrence of an event without which the event cannot occur. Sufficient condition—A condition for the occurrence of an event that guarantees that the event occurs.