I agree that this probably isn't straight-out lying, in that someone who asks (e.g.) "Will allowing gay marriage decrease the rate of marriage overall?" probably isn't thinking "Of course allowing gay marriage isn't likely to decrease the rate of marriage overall... honestly, how many people will refuse to get married simply because a gay couple down the block is getting married? But if I ask the question, people will start to think that it will, because people are easy to manipulate that way."
Of course allowing gay marriage isn't likely to decrease the rate of marriage overall... honestly, how many people will refuse to get married simply because a gay couple down the block is getting married?
Yes, when you only consider the most straight forward causal path, of course, it seems absurd. (Incidentally, the problem with attempting to think of politics in utilitarian terms is that it makes it easy to make these kind of mistakes.) The causal path is about undermining the Schelling points on which marriage is based.
The reason the institution of ...
So you're playing the credence game, and you’re getting a pretty good sense of which level of confidence to assign to your beliefs. Later, when you’re discussing politics, you wonder how you can calibrate your political beliefs as well (beliefs of the form "policy X will result in outcome Y"). Here there's no easy way to assess whether a belief is true or false, in contrast to the trivia questions in the credence game. Moreover, it’s very easy to become mindkilled by politics. What do you do?
In the credence game, you get direct feedback that allows you to learn about your internal proxies for credence, i.e., emotional and heuristic cues about how much to trust yourself. With political beliefs, however, there is no such feedback. One workaround would be to assign high confidence only to beliefs for which you have read n academic papers on the subject. For example, only assign 90% confidence if you've read ten academic papers.
To account for mindkilling, use a second criterion: assign high confidence only to beliefs for which you are ideologically Turing-capable (i.e., able to pass an ideological Turing test). As a proxy for an actual ideological Turing test, you should be able to accurately restate your opponent’s position, or be able to state the strongest counterargument to your position.
In sum, to calibrate your political beliefs, only assign high confidence to beliefs which satisfy extremely demanding epistemic standards.