Perhaps it’s better to view debates as providing social evidence in both directions, rather than anything actually persuasive.

Eliezer and Gary, follow the link for the titles.

blink, watch or listen to a debate to find out what folks were told.

About the idea that it’s easier to steal votes from the other side if they have a large initial lead: shouldn’t the arguments of a position with, for example, 90% support be good enough to convince 9 people for every 1 the other side convinces? If they’re not, why does the position deserve to have 90% support?

…and where is *your* “economist’s hat”? Please provide pictures!

Each debate reports the polling results before and after, as percent favoring, percent opposed, and percent undecided. The “contrarian” position is whichever has the smaller percentage supporting it initially, and the “favorite” position is the one with the larger percentage. Because the percent undecided changes before and after, contrarian and favorite positions do not move the same amount or even necessarily the same direction. So we see rather different effects in the two charts.

The red lines are not fits, they are the X=Y lines; if people’s positions did not change at all, all of the points would be on a red line.

One thing I saw (not shown in the charts) is that undecided seems to (at least, almost) always decrease. People feel that they are becoming more certain in their views. That argues against interpretations where people get confused by being exposed to both sides.

It seems plausible that much of the change in position comes from undecided people adopting one of the two sides. That wouldn’t explain all of it but it could explain a lot. Taborek argues that the before-undecided are lying, and were not really undecided. (Maybe they are following a social convention of adopting an unbiased stance before hearing the arguments.) Then you have to assume that these pseudo-undecideds have more moderate views than those who are willing to admit to having made up their minds beforehand.

Visually, the effect looks stronger with the contrarian than the favorite position. That would mean (in this interpretation) that people with the unpopular view are more likely to lie and claim to be undecided beforehand. That could make sense if people are used to hiding unpopular views.

I would expect a debate between two qualified opponents to present a mutually comparable number of arguments that the presenters have researched and understand, to an audience who does not. As a result, the real state of people’s minds after a debate is not a changed opinion, it is confusion. When asked what opinion they now lean to, people will respond as if they were asked the question “which side’s arguments do you recall the most right now”. If the debaters were equally good, this is probably a linear function of how much time each debater got to speak.

Weighing the merits of substantive arguments is a bit like compiling code. It requires time, attention and precision, and cannot be done on the fly during a debate.

Measure people’s opinions a week or a month after the debate, and you will know how much they were really affected.

Also, it looks like the source data includes percent undecided. Does your analysis change if you consider these percents? (If the only effect of the debate were to cause undecided people to commit randomly, then that would increase the percentage for the underdog position, but probably should not be interpreted as an increase in support.)

Nevertheless, did the audience know whether they are on the favourite or contrarian side? Are there any data about strength of their beliefs before and after the debate? Has the audience consisted of people who are aware of cognitive biases or it has been a typical sample of general public?