5. What is a Good Argument (II)?

Now that we’ve discussed the Truth Condition and the Logic Condition in more detail, we can state the conditions for an argument to be good with more precision than in our first attempt.

The Concept of a Good Argument

The basic concept is straightforward:

An argument is good if it offers its intended audience good reasons to accept the conclusion.

What we’ve been trying to do in this lecture series is clarify what we mean by “good reasons”. We broke it down into two different components, one relating to the truth of the premises, another relating to the logical relationship between the premises and the conclusion.

First Pass

Our first pass at a clarification of what “good reasons” means was stated in terms of two necessary conditions that must be fulfilled for the argument to count as good:

The Truth Condition:

The argument has all true premises

The Logic Condition:

The conclusion follows from the premises.

This is helpful, but it needed further analysis to clarify what we mean by “true” and what we mean by “follows from”.

Second Pass

The last four lectures have introduced a set of concepts that let us articulate more clearly the conditions that an argument must satisfy for it to count as good:

The Truth Condition:

All the premises are plausible (to the intended audience)

The Logic Condition:

The argument is either valid or strong.

This is much more specific, and for purposes of argument analysis, much more helpful.

We use “plausible” to highlight the fact that a given premise might be regarded as true by one audience but as false by another, and what we want are premises that are regarded as true by the target audience of the argument. A plausible premise is one where the audience believes it has good reason to think it’s true, and so is willing to grant it as a premise. This helps to distinguish a plausible premise from a reading of “true premise” that’s defined in terms of correspondence with the objective facts. We’d like our premises to be true in this sense, but what really matters to argument evaluation is whether they’re regarded as plausible or not by the intended audience of the argument.

We use “valid” and ‘strong” to help specify precisely what we mean when we say that the conclusion follows from the premises. A valid argument is one where the conclusion follows with absolute certainty from the premises, where the truth of the premises logically necessitates the truth of the conclusion. A strong argument is one where the conclusion follows not with absolute certainty, but with some high probability. Together, these help to clarify what we mean when we say that an argument satisfies the Logic Condition.

Altogether, these definitions of plausibility, validity and strength give us a helpful set of tools for assessing the quality of arguments.