Some people want to be politicians. They do best by joining an existing party or movement and adopting all their political opinions except for maybe one or two issues they personally care about.
Other people want to affect policy on a certain issue, and they decide to do so via politics. But once they enter politics, to get things done and based on the personal contacts they develop, I think most of them (not all) tend to affiliate with a party and again adopt their other opinions.
And yet other people (the majority, I think) try to affect policy without becoming politicians. Most changes in effective policy happen because a new product becomes available on the market, because someone expands or curtails a service, because someone changes prices by R&D or by contributing money to an existing concern. And these people can remain free of politics if they want to.
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.