By Arnold Kling
If virtually everyone just argues for whatever position he was born into, a truth-seeker should hold the gladiators for popular views to higher standards.
I have a slightly different way to arrive at this position. Consider the following matrix.
|Ideas that are||Popular||Unpopular|
Ideas that are in quadrant I are popular and empirically valid. Think of the law of gravity. Those ideas have the best survival characteristics.
Ideas that are in quadrant II are unpopular but empirically valid. I would put the proposition that “immigration hurts the economy very little, if at all” in that quadrant. These ideas are always a threat to take over for popular ideas, should people adopt an empiricist approach to the issue.
Quadrant III is the mirror image of quadrant II. Creationism is popular, but not empirically valid. These sorts of ideas are threatened by empiricism.
Quadrant IV are ideas that are neither popular nor empirically valid. They threaten to become extinct once their few adherents change their minds or die. Freudian psychology was in quadrant III 50 years ago, and is in quadrant IV today.
If we look at ideas that are alive at any one point in time, they are alive either because they are popular, because they are empirically valid, or both. So if an idea is very popular, you should hold it to a high standard of empirical validity. If it is somewhat less popular, then there is a good chance that the only reason it survived is that it has some empirical validity.
The old joke says that as a lawyer, when you have neither the facts with you nor the law with you, you pound the table. There are table-pounding methods of argument in ordinary discussions, and when you observe people using them, you should assume that the empirical evidence runs the other way.