What a Good Argument Isn't and What a Good Argument Is

It is sometimes claimed that a good argument is whatever would compel a rational inquirer — or perhaps, most among a group of rational inquirers — to accept the truth of its conclusion.

Philosopher Tim McGrew says this should not be the criterion for what counts as a good argument.¹ He offers three reasons:

First, many bad argument often do persuade the majority of inquirers. The history of philosophy and science are littered with instances of this.

Second, there are may well be recognizably good arguments which do not (and perhaps should not) persuade most inquirers of the truth of their conclusions.

Third, “… it does not provide the conceptual resources to represent the fact that the goodness of arguments, like the goodness of many other things, can come in degrees.”

In place of the aforementioned criterion, McGrew offers the following:

“First, an argument may be good in the sense that it shows, from premises widely available available to rational inquirers, that its conclusion has a nonnegligible probability. That probability need not exceed 50%.”

“Second, an argument may be good in the sense that to the extent it shifts the ratio of probabilities in favor of its conclusion…. For example, an argument that lifts the probability of C from 1% to 25%… even though 25% is not a probability that would underwrite belief in C, the evidence E provides significant confirmation for C. A number of such arguments taken together may provide a cumulative case of great power for C.”

Personally, I find McGrew’s account the more satisfying of the two.

1. All found in Four Views on Christianity and Philosophy.