The Language of Argument

8 7

A r r a n g i n g su b a r g u m e n t s

Although it is often illuminating to break an argument into stages and

arrange them in a linear series, this can be misleading if done incorrectly.

For example, the first sentences of Kyl’s speech cited in Chapter 4 read as

follows:

Mr. Speaker, I oppose this measure. I oppose it first because it is

expensive. I further oppose it because it is untimely.

If we try to force this into a simple line, we might get this:

(1) This measure is expensive.

∴(2) This measure is untimely. (from 1)

∴(3) I oppose this measure. (from 2)

This reconstruction suggests that the measure’s being expensive is what

makes it untimely. That might be true (say, during a temporary budget cri-

sis), but it is not what Kyl actually says. Instead, Kyl is giving two separate

reasons for the same conclusion. First,

(1) This measure is expensive.

∴(2) I oppose this measure. (from 1)

Second,

(1*) This measure is untimely.

∴(2) I oppose this measure. (from 1*)

The structure of this argument can now be diagrammed as a branching tree:

(1) (1*)

(2)

The two arrows indicate that there are two separate reasons for the conclu-

sion. Because this structure resembles the way branches split off from the

trunk of a tree, we can describe this structure as branching. We have to be

careful not to confuse branching arguments like this with linear chains of

arguments that do not branch.

We also need to distinguish this branching structure from cases where several

premises work together to support a single conclusion. Consider this argument:

My keys must be either at home or at the office. They can’t be at the

office, because I looked for them there. So they must be at home.

With some clarifications, we can put this argument in standard form:

(1) My keys are either at my home or at my office.

(2) My keys are not at my office.

∴(3) My keys are at my home. (from 1–2)

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