Rhetoric in logical discourse
In The Myth of the Rational Voter, Bryan Caplan has a short section on the role of rhetoric in discourse, which is something that I’ve been thinking about for a long time now. In Caplan’s analysis, he makes the case that since people have preferences over beliefs, being right isn’t sufficient to convince them that what you are saying is true – you also have to make your case in a way that takes into account their preferences. Consider someone who holds two contradictory beliefs – you could start by attacking the one that you think is wrong, or you could start by providing support for the one that you think is right, then pointing out that the beliefs are contradictory. In the first case, you’d be putting them on the defensive, while in the second case you are appealing to their desire to be correct.
Overall, you could say that people analyze arguments on (at least) two dimensions – the rhetorical dimension and the logical dimension, and how likely you are to convince someone that you have a valid point depends on some weighted sum of the two. As far as I can tell, this can cause serious problems for the use of logical discourse to aggregate information. In the most simplified case, you have on piece of information – whether or not your opponent agrees with you – but two variables – how effective your rhetoric was and how good your logic and information are. Without knowing how these factors are weighted, you can’t reliably use discourse to aggregate information.
I’m not really sure how everything plays out, though. The nature of the effect of rhetoric on someone’s analysis of a given topic is not well-defined in this model and as such it is hard to determine what the possible aggregate effects are. This does, however, lead me to a much softer stance on failing to concede than I once took. A few years ago, I was frequently extremely frustrated by the fact that many people would concede the fact that they could not offer a counter-argument to points that I made in debate, but they also refused to change their belief. If their belief was rational, they should be able to defend it. If not, they should give it up. However, this ignores the fact that it is possible that they found my arguments convincing for some rhetorical reason. Perhaps I used some subtle wordplay to distract them from the weak points in my arguments (maybe even without knowing about it). Without knowing how much of my argument was strong because I am good at debate and how much was strong because I am good at logic, the fact that they could not win an argument with me did not necessarily mean that I was right. Hopefully the fact that I bested you weighs in favor of re-analyzing the beliefs that you found yourself unable to defend, but it need not mean that you should immediately switch sides.
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