2.10: Locating Unstated Conclusions

Just as we detect missing premises by using our knowledge of indicator terms and of what is needed for deductive validity and inductive strength, so we can also use that knowledge to detect missing conclusions. What is the implicit conclusion in the following argument?

All insects have exactly six legs, but all spiders have exactly eight legs, so now what do we know about whether spiders are insects?

You, the reader, have to figure out the conclusion for yourself: that spiders are not insects.

Figure \(\PageIndex{1}\)

People who are unwilling to do this detective work will miss the point of many passages. Here is a slightly more difficult passage that expects you to find the implicit conclusion. What is it?

The Academy of Motion Picture Arts and Sciences was formed, in 1927, with a brief “to raise the cultural, educational, and scientific standards” of film. That noble purpose was sustained until July 12, 2013, the release date for the film “Grown Ups 2,” in which a frightened deer urinates on Adam Sandler’s face. In the animal’s defense, one could argue that it was merely taking movie criticism to a higher and more clarifying level.

A “brief” is a directive. That final comment about the deer taking movie criticism to a higher and more clarifying level was a humorous remark, not meant to be taken literally. The implicit conclusion is that the noble purpose of the Academy of Motion Picture Arts and Sciences was no longer sustained after July 12, 2013. One of the major reasons in support of this conclusion is also implicit: that the deer’s urinating on Adam Sandler’s face in the film “Grown Ups 2” on July 12, 2013 did not achieve the noble purpose of the Academy.

Exercise \(\PageIndex{1}\)

What is the implicit conclusion you are supposed to draw in the following joke?

My father had a lot of patience with me when I was growing up. Whenever he got mad at me he would slowly count to ten. Then he'd lift my head out of the water.

a. All people have fathers.
b. My father had a lot of patience with me when I was growing up.
c. My father was impatient with me when I was growing up.
d. My father would lift my head out of the water after a slow count to twenty.

Answer

The argument is an indirect way of saying my father was impatient, so the answer is (c).

Unstated premises are very common. Unstated conclusions are less common and more difficult to uncover. If you were presented with the following conditional and knew nothing else, then it wouldn’t be an argument. It would just be a claim. But let’s suppose you can tell from the background situation that an argument is intended. If so, what’s the conclusion and the key missing premise?

If it looks like a duck, walks like a duck, and quacks like a duck, then it's a duck.

Figure \(\PageIndex{1}\)

The unstated conclusion is that it’s a duck. All you have explicitly is one premise. The other premise is that it does look like a duck, walk like a duck, and quack like a duck.

What is the unstated conclusion you are supposed to draw from the following piece of reasoning by an upset American?

Figure \(\PageIndex{1}\)

I can't feed my kids, and whitey’s on the moon. Rats bit my little sister. Her leg is swelling, and whitey's on the moon. The rent is going up. Drug addicts are moving in, and whitey's on the moon.

The unstated conclusion is that the government’s spending priorities are faulty, specifically that the government, which is run by white people, spends too much on moon shots and not enough on social services for poor non-white people. It can be very difficult to distinguish a jumble of statements from a group of statements intended to have a conclusion that you draw yourself. There is no mechanical way of telling which is which. However, it often can be done, and in this group of statements about whitey on the moon, no one would have said them this way unless they expected their reader to draw that conclusion about the government’s spending priorities.

Later in this book we will be analyzing arguments and not simply finding them, but while we have this argument in front of us, let’s briefly analyze it. At a deeper level, the argument is one-sided because it finds many reasons for why we should think the spending priorities are faulty while paying no attention to reasons for why the government might be making the right decision in sending a person to the moon. A high-level analysis would try to uncover what those reasons might be, then weigh the pros and cons of changing government spending priorities. Also, a good reasoner will not simply attack the argument in the passage, but also should mention how the arguer could make an improved case for the conclusion. We won’t stop here to make that improved case. If we turn now from analysis to rhetoric, it should be pointed out that the argument is very eloquent, not the kind of dry writing one finds in a philosophy journal. This eloquence will help a reader remember the argument long after a similar argument written in the usual newspaper-ese is forgotten.

OK, let’s return to the problem of uncovering arguments. Occasionally a clever or diabolical speaker, will present all sorts of reasons for drawing an obvious conclusion but will never quite draw that conclusion for you. The speaker is disguising an argument. On the other hand, the speaker could get defensive and say, "I didn't make that argument, you did." Speakers who are good with innuendo do this to you.

When you are in that situation and faced with some statements that could constitute an argument with an implicit conclusion, but maybe do not, then how do you tell whether you have an argument or not? There is no simple answer to this question; it is a matter of the delicate application of the principle of fidelity. If it is clear what conclusion the writer hopes you will draw, then there is an argument; if not, there is no argument. But there can be borderline cases where it is just not clear what the answer is, and so you need more information.