In some cases, your goal is to figure out the “correct” political position to hold (based on your ethics, goals, and other beliefs). In that scenario, what any particular person believes is, logically speaking, irrelevant[1]. (If you’re debating a certain person, then it’s probably rude and possibly against the rules of the debate (if there are any) for you to spend all your time talking about positions your opponent doesn’t hold, and never engage with their actual views; so that’s a reason to talk about their actual views, but not a reason to believe them any more than other potential views you find equally plausible.)
In other cases, your goal is to decide if some political movement is a good one, or whether to support a political party or coalition or group. In that case, questions like “How many of you actually support position X vs position Y” are relevant. (And “How much better is X than Y” is also relevant, if there are enough supporters of those positions to be worth considering.)
Truthseekers do well to bear in mind the difference between these goals, and when questions bear on one but not the other.
In some cases, your goal is to figure out the “correct” political position to hold (based on your ethics, goals, and other beliefs). In that scenario, what any particular person believes is, logically speaking, irrelevant[1]. (If you’re debating a certain person, then it’s probably rude and possibly against the rules of the debate (if there are any) for you to spend all your time talking about positions your opponent doesn’t hold, and never engage with their actual views; so that’s a reason to talk about their actual views, but not a reason to believe them any more than other potential views you find equally plausible.)
In other cases, your goal is to decide if some political movement is a good one, or whether to support a political party or coalition or group. In that case, questions like “How many of you actually support position X vs position Y” are relevant. (And “How much better is X than Y” is also relevant, if there are enough supporters of those positions to be worth considering.)
Truthseekers do well to bear in mind the difference between these goals, and when questions bear on one but not the other.
Except to the extent that person X believing Y is taken as evidence that Y is true. That would apply where X is known to be an expert on Y.