The Language of Argument

2 2 8

C H A P T E R 1 0 ■ C a u s a l R e a s o n i n g

Nonetheless, if our background assumptions are justified, the fact that

conditions 1–5 are all met can still provide a strong reason for the positive

conclusion that candidate C is a necessary condition for target G.

The SCT and NCT themselves are still negative and deductive; but that does

not make them better than the positive tests encapsulated in conditions 1–5.

The negative SCT and NCT are of no use when we need to argue that some

condition is sufficient or is necessary. Such positive conclusions can be reached

only by applying something like condition 5, which will require background

information. These inductive arguments might not be as clear-cut or secure

as the negative ones, but they can still be inductively strong under the right

circumstances. That is all they claim to be.

Applying These Methods to Find Causes

In stating the SCT and NCT and applying these tests to abstract patterns

of conditions to eliminate candidates, our procedure was fairly mechanical.

We cannot be so mechanical when we try to reach positive conclusions that

certain conditions are necessary, sufficient, or both. Applying these rules

to actual concrete situations introduces a number of further complications,

especially when using our tests to determine causes.

Normality

First, it is important to keep in mind that, in our ordinary understanding of

causal conditions, we usually take it for granted that the setting is normal.

It is part of common knowledge that if you strike a match, then it will light.

Thus, we consider striking a match sufficient to make it light. But if someone

has filled the room with carbon dioxide, then the match will not light, no

matter how it is struck. Here one may be inclined to say that, after all, strik-

ing a match is not sufficient to light it. We might try to be more careful and

say that if a match is struck and the room is not filled with carbon dioxide,

then it will light. But this new conditional overlooks other possibilities—for

example, that the room has been filled with nitrogen, that the match has

been fireproofed, that the wrong end of the match was struck, that the match

has already been lit, and so forth. It now seems that the antecedent of our

conditional will have to be endlessly long in order to specify a true or genu-

ine sufficient condition. In fact, however, we usually feel quite happy with

saying that if you strike a match, then it will light. We simply do not worry

about the possibility that the room has been filled with carbon dioxide, the

match has been fireproofed, and so on. Normally we think that things are

normal, and give up this assumption only when some good reason appears

for doing so.

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