The Language of Argument

2 4 2

C HaP Te r 1 1 ■ C h a n c e s

Th e av a i l a b i l iT y he uR i sT i c. Because sampling and taking surveys is

costly, we often do it imaginatively, that is, in our heads. If you ask a base-

ball fan which team has the better batting average, Detroit or San Diego, that

person might just remember, might go look it up, or might think about each

team and try to decide which has the most good batters. The latter approach,

needless to say, would be a risky business, but many baseball fans have re-

markable knowledge of the batting averages of top hitters. Even with this

knowledge, however, it is easy to go wrong. The players that naturally come

to mind are the stars on each team. They are more available to our memory,

and we are likely to make our judgment on the basis of them alone. Yet such

a sample can easily be biased because all the batters contribute to the team

average, not just the stars. The fact that the weak batters on one team are

much better than the weak batters on the other can swing the balance.

Linda is thirty-one years old, single, outspoken, and very bright. As a student,

she majored in philosophy, was deeply concerned with issues of discrimina-

tion and social justice, and also participated in antinuclear demonstrations.

Rank the following statements with respect to the probability that they are also

true of Linda, then explain your rankings:

Linda is a teacher in elementary school.

Linda works in a bookstore and takes yoga classes.

Linda is active in the feminist movement.

Linda is a psychiatric social worker.

Linda is a bank teller.

Linda is an insurance salesperson.

Linda is a bank teller and is active in the feminist movement.^1

Discussion Question

In four pages of a novel (about 2,000 words), how many words would you

expect to find that have the form _ _ _ _ _n_ (seven-letter words with “n” in

the sixth place)? Write down your answer. Now, how many words would you

expect to find that have the form _ _ _ _ing (seven-letter words that end with

“ing”)? Explain your answers.^2

Discussion Question

The point of examining these heuristics and noting the errors that they

produce is not to suggest that we should cease relying on them. First, there

is a good chance that this would be psychologically impossible, because

the use of such heuristics seems to be built into our psychological makeup.

Second, over a wide range of standard cases, these heuristics give quick

and largely accurate estimates. Difficulties typically arise in using these

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