Lecture Notes

Lecture Notes by Christopher Lay

Los Angeles Pierce College

Department of History, Philosophy, and Sociology

Mathew Van Cleave's 2016 Introduction to Logic and Critical Thinking

https://open.umn.edu/opentextbooks/BookDetail.aspx?bookId=457

Chapter 3 "Evaluating Inductive Arguments and Probabilistic and Statistical Fallacies," § 2 "Inference to the Best Explanation and the Seven Explanatory Virtues"

"Inference to the best explanation is a form of inductive argument whose premises are a set of observed facts, a hypothesis that explains those observed facts, and a comparison of competing explanations, and whose conclusion is that the hypothesis is true."

Reasonable

"[I]n order to make a strong inference to the best explanation, the favored explanation must be the best (or the most reasonable)."

To determine the best explanation, it is useful to compare two or more explanations.

Explanatory Virtues

"There are certain conditions that any good explanation must meet."

"The more of these conditions are met, the better the explanation."

Explanatoriness

Depth

Power

Falsifiability

Modesty

Simplicity / Ockham’s Razor

Conservativeness

Explanatoriness

"[T]he hypothesis proposed must actually explain all the observed facts."

My take: of two explanations, the one that can explain more of the observed facts is superior to one that cannot explain as many.

Depth

"Explanations should not raise more questions than they answer."

An "explanation [that] raises as many questions as it answers ... lacks the explanatory virtue of 'depth.'"

Power

"Explanations should apply in a range of similar contexts, not just the current situation in which the explanation is being offered."

Of two competing explanations, if one can explain the observed facts in question, and other, similar observable facts, then it is superior to the explanation that only explained the observed facts in question.

Falsifiability

"Explanations should be falsifiable—it must be possible for there to be evidence that would show that the explanation is

incorrect."

If a hypothesis appeals to unobservable, or unverifiable evidence, then there is a problem with falsifiability.

If "there is no way to observe [evidence, then the evidence] seems you can never prove nor disprove the existence of the [the evidence]. Thus, you can neither confirm nor disconfirm the hypothesis."

"Any empirical hypothesis (i.e., a hypothesis that is supposed to explain a set of observed facts) must at least be able to be shown false."

"The different between a true hypothesis and a false one is simply that the true hypothesis has not yet been shown to be false, whereas the false one has."

"Falsifiability requires only that it be possible to show that the hypothesis is false."

"If we look for evidence that would show that the hypothesis is false, but we won’t find that evidence, then we have confirmed that hypothesis. In contrast, an unfalsifiable hypothesis cannot be confirmed because we cannot specify any evidence that would show it was false, so we can’t try to look for such evidence (which is what a rigorous scientific methodology requires)."

Modesty

"Explanations should not claim any more than is needed to explain the observed facts."

"Any details in the explanation must relate to explaining one of the observed facts."

"The problem [of modesty occurs when] the hypothesis is far more specific than it needs to be in order to explain the relevant observed facts."

"The details in any explanation should be relevant to explaining the observed facts."

If the "details [do not] help us to understand why the observed facts occurred" then there is a problem with modesty.

Simplicity

"Explanations that posit fewer entities or processes are preferable to explanations that posit more entities or processes. All other things being equal, the simplest explanation is the best. This is sometimes referred to as “Ockham’s razor” after William of Ockham (1287-1347), the medieval philosopher and logician."

"The explanatory virtue of 'simplicity' tells us that all other things being equal, the simplest explanation is the better explanation."

"More precisely, an explanation that posits fewer entities or processes in order to explain the observed facts is better than an explanation that posits more entities and processes to explain that same set of observed facts."

Simplicity in the Sciences

"In the domain of science, upholding simplicity is often a matter of not positing new entities or laws when we can explain the observed facts in terms of existing entities and laws."

"[T]here is nothing wrong with positing new laws or entities—that is how science progresses."

"Simplicity doesn’t say that one should never posit new entities; that would be absurd. Rather, it tells us that if the observed facts can be explained without having to posit new entities, then that explanation is preferable to an explanation that does posit new entities (all other things being equal)."

"Of course, sometimes the observations cannot be explained without having to change the way we understand that world. This is when it is legitimate to posit new entities or scientific laws."

Conservativeness

"Explanations that force us to give up fewer well- established beliefs are better than explanations that force us to give up more well-established beliefs."

"[B]etter explanations are ones that force us to give up fewer well-established beliefs."

"[C]onservativeness is an explanatory virtue only when we are considering two explanations that each explain all the observed facts, but where one conflicts with well-established beliefs and the other doesn’t."

"In such a case, the former explanation would lack the explanatory virtue of conservativeness, whereas the latter explanation would possess the virtue of conservativeness."

Exercise 23