Two of the three main parts of the course are now done: logical preliminaries, reconstruction and evaluation. We have all the basic techniques. What remains is to apply this to reasoning of various kinds. In the next several weeks we will apply the techniques already developed to arguments of these different kinds. Some of this is in the text, but some is not. The text covers:

testimonial arguments, statistical arguments (including “past-to-future” arguments), causal arguments, and moral arguments. There will be little discussion of testimonial arguments in class.

 

It will be useful to put all of this into a larger context. Arguments and explanations are connected in important ways. When you know that something has happened, and you know that something else provides a good explanation of why it happened, then you can have a good argument for the conclusion that the something else did happen. E.g., if on a snowy winter day I get home from work and see tire tracks in my driveway going right into the garage, I will think that my wife already got home and drove through the snow. I make an inference from what I observe to the truth of what explains it. This is often called “inference to the best explanation.” The various arguments types we will discuss can be seen as being of this type.

 

I. Preliminaries

Typically, explanations answer “why” questions. They can be introduced with the word “because”.
Some technical terms: explanandum - the thing being explained; explanans - the thing that does the explaining.

 

II. Three Kinds of Explanation

A. General patterns - explain something by showing that it fits under a general pattern. “Why is class meeting at 11:00 today? Because that is when it always meets.” These explanations are often not terribly helpful, they don’t go very deep. But they are not empty, since they do provide some information.

 

Statistical explanations can be seen as fitting under this heading. Suppose I notice that 10% of the students in my class showed up the day before break. I wonder why that is. A colleague might say that about this percentage showed up in all classes that day. And that would be a kind of explanation.

 

Consider next samples and polling. Suppose we call up a bunch of people and ask who they are going to vote for. And 52% say that they will vote for candidate A. We sometimes generalize from this, and conclude that 52% of all people will vote for candidate A. And you can think of this as an inference saying that the best explanation of the sample is that it fits the general pattern.

 

B. Causal - explain something by identifying its causes. “Why did ‘Million Dollar Baby’ win the Academy Award?” Because people are suckers for sappy stories about underdogs. We will say a lot more about this sort of explanation later. They are perhaps the most important kind of explanation.

 

C. Teleological - explain something in terms of goals or purposes. “Why did you give your dog a treat when he sat down (after you said “sit”)?” Explanation - to reward him. This explains in terms of goals or purposes. And notice that the goal can explain even if it is not achieved. “Why did you pay so much for that haircut?” Explanation - in order to look good. “Too bad. It didn’t work.”

 

There is much discussion of these kinds of explanations. But they, too, are best seen as causal explanations.

 

He got an expensive haircut in order to look good

 

is equivalent to

 

He got an expensive haircut because he wanted to look good and believed that getting an expensive haircut would make him look good.

 

And this is a causal explanation. So teleological explanations of human behavior make clear sense - they are just alternative statements of causal explanations. These causal explanations do bring in the goals of agents with intentions and plans. We can say that they are causal/teleological explanations. Lots of causal explanations are not like this - no reference at all to anyone’s goals or plans.

 

III. Best Explanations

 

Inference to the best explanation. (IBE)

 

Suppose you observe something, O. And you say that E best explains O. And you conclude that E is true.

 

Note: a) This is not a valid argument. But, as we will see, we can spell out the details of arguments to make them valid or cogent.

 

b) The conclusions of these arguments are hypotheses or theories. We could worry a lot about just what these words mean, but the main point is that they contrast with observations. Observations are things that you directly perceive yourself. (That’s not assumed to be very informative.) But the idea is that there are certain things that you perceive and other things that go beyond your perceptions or observations. You perceive tire tracks in the snow, and infer that a car drove through.

 

c) There is a question about observation that should be noted. The question concerns how much you really observe in any particular situation. Did you really observe tire tracks in the snow, or merely an impression of a particular shape and size? Or, to take another case, witnesses to crimes are often called upon to say what they saw or observed. And careful questioning, often by defense attorneys, gets them to say that what they really observed is less than they might have initially claimed. Thus, a witness, W, might say that he saw A kill B. But he might have to admit that all he “really” saw was that A shot B and then B fell down while bleeding heavily. He didn’t “see” that the shot caused B’s death. B might have independently had a heart attack just before the shot, or died from poisoning, etc. These (typically implausible) alternatives are possible, in the sense that they are compatible with what W observed. So W retreats in what he claims to observed. It can go back further. Did W really observe that A shot B, where this implies that a bullet from A’s gun entered B. Well, he saw A squeeze the trigger, heard the sound, and then saw what happened to B. But maybe there was another unheard shot at just the same time from someone out of view, and this other one actually hit B.

These thoughts are not intended to make you skeptical. But they show that there is more inference in what is ordinarily regarded as observation than is ordinarily thought. To the extent that you think W is well justified in initial claims, it is in part because you accept the IBE argument from his more minimal observation to the conclusion that A killed B. So these thoughts really help you to see that you in effect presuppose that IBE arguments can be good ones. And there’s no reason to think that you are mistaken about that.

 

d) But the considerations just mentioned also give you reason to question IBE arguments in some cases. If someone offers one (or you yourself think of one), you can ask whether it’s really true that O was observed or that it is a reasonable inference from what is observed

 

e) People sometimes use “theory” and “hypothesis” as ways to diminish the status of something - “It’s just a theory”. Sometimes the idea seems to be that when it comes to theory, you can reasonably believe any one that you like, or that all theories are equally reasonable. (Naive contributions to the evolution/creationism debate sometimes seem to say something like that. Thus, people think that because evolution is “just a theory” and creationists have another theory, both should be taught in schools. Whatever the merits of evolution and creationism, this particular line of thought seems to rely on the idea that all theories have equal status. If it does, then it’s mistaken.) This is wrong. IBE arguments can be good ones. When a strong IBE arguments supports one explanation, it is unreasonable to believe some competing explanation.

 

f) It’s worth emphasizing that IBE arguments are not valid. This implies that it is possible for the premises to be true and the conclusion false. It’s no good criticism of such an argument to point out an alternative possibility. What must be shown is that the alternative is good enough to diminish the reasonableness of the conclusion.

 

g) A main thing to think about in all these cases is whether there is some other reasonably plausible explanation. Could the observation plausibly not come from the general pattern or the cause that the explanation appeals to?