Logic and Dialogue

by Scott F. Aikin and Robert B. Talisse

PlatoIn last month's post, we contrasted a formal conception of argument with a dialectical one. We claimed that a dialectical model must be developed in order to capture the breadth not only of the good arguments we give, but also the bad. To review, the formal conception takes arguments as products, specifically as sets of claims with subsets of premises and conclusions. These arguments are understood as abstract objects, and they are, as one might say, purely logical entities. By contrast, the dialectical perspective sees arguments as more like processes; they happen, unfold, emerge, and they take various twists and turns. They erupt, get heated, go nowhere or cover ground. In short, on the dialectical conception, arguments are events of reason-exchange between people. And just as there are rules for argument-construction as formal entities, there are rules for good argument-performance as interpersonal processes.

The first thing to note is that argument-as-process is a turn-taking game. Alfred and Betty may disagree – perhaps Alfred accepts some proposition, p, and Betty rejects p. They aim to resolve their disagreement through argument. They could, of course, resolve the disagreement through other means – Alfred could threaten Betty, or bribe her – but they, instead, decide to enact a means of deciding the matter according to their shared reasons. That's argument, and the point is to share and jointly weigh the reasons. That's where the turn-taking is important. Alfred presents his reasons, and Betty presents hers. They respond to each other's reasons in turn.

A few things about the turn-taking are worth noting. When the sides present their respective cases, they present arguments in the formal sense – they articulate sets of claims comprised by premises and conclusions. The other side, then, may accept the premises but hold they don't support the conclusions, or they may hold that the premises themselves are false or unacceptable. Or they may change their minds and accept the conclusion. In that case, the argument concludes: Dispute resolved. Otherwise, what the two sides do is give each other reasons and then take turns giving each other reasoned feedback about how to change their arguments so they can rationally be better, or how they can change their views to fit with the rationally better reasons. When it's well-run, argument is a cooperative enterprise. Hence it's not uncommon to use the term argumentation in discussions of the dialectical conception of argument.

The turn-taking element of argumentation makes the feedback process possible. And this feedback process is what separates argumentation from simple speechmaking or sermonizing. But there's no guarantee that things will work out like they should. Sometimes, there are misfires in argumentation. One common misfire involves misrepresenting the other side in providing critical feedback. The straw man fallacy occurs specifically when one side strategically misrepresents the other side's arguments as weaker than those they actually gave. Straw-manning is a dialectical fallacy par excellence – it is a failure of the turn-taking element of proper argumentative exchange; it's a turn that doesn't properly respond to the contents of the previous turns.

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Winning at Argument

by Scott F. Aikin and Robert B. Talisse

Lo Cole ArgumentWe’re currently finishing work on the manuscript for our forthcoming book, Why We Argue (And How We Should), so we’ve been thinking a lot recently about argumentation. We’ve been especially concerned with how arguments can go wrong. When evaluating an argument, one of the central questions to ask is whether the stated premises support the proposed conclusion. When the premises fail to provide the right kind of support for the conclusion, we often call the argument (and its form) fallacious. Fallacies are so pervasive precisely because they are cases in which it looks as if the stated premises provide propose support for a proposed conclusion, but in fact they don’t. Take, for example, a simple textbook fallacy, that of asserting the consequent:

If Bill’s a bachelor, Bill is male.

Bill is male, therefore Bill is a bachelor.

The trouble with an argument of this form is that it presents an invalid inference — the premises, if true, don’t guarantee the truth of the conclusion. So even were the premises and the conclusion true, the proposed argument fails. Note that the failure is a matter of the proposed argument’s form rather than its content. The objective of fallacy detection in the formal mode is to reveal cases in which the truth of the stated premises fail to provide the proper kind of support for the conclusion.

In the formal mode, we also can identify different degrees in which premises provide support for a conclusion. The highest degree of support that premises can provide for a conclusion is the guarantee of its truth, given the truth of the premises. Arguments that manifest that feature are called deductively valid. But note that deductive validity does not depend on the stated premises actually being true. That is, with a valid argument, the conclusion is guaranteed to be true, if the premises are true. Accordingly, an argument can be deductively valid even if every one of its stated premises is false.

Thus we require an additional metric of formal success. It would seem that an argument that is both deductively valid and has premises that in fact are all true would be bombproof. Such arguments are called deductively sound. Notice that deductive soundness encompasses deductive validity in that every sound argument is valid. A deductively sound argument is a deductively valid argument that has true premises. Since a deductively valid argument is one that guarantees the truth of its conclusion provided that its premises are in fact true, it should be no surprise that deductive soundness is often considered the gold standard for argumentative success. Every deductively sound argument actually establishes the truth of its conclusion. Who could ask for more than that?

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