Another: two polar opposite political stances can be true at the same time. Immigraton can be and is both good and bad. So are social help programs. Guns. Government intervention. Surveilance. Etc. Your truth is not the only truth. There are an infinite true perspectives on a issue. Another perspective is not false just because it opposes yours and yours is true.
I don't think this is a helpful way of saying this. There is, in fact, only one truth in terms of what the facts are. All of us have different models in our head of what the world is like; these models are incomplete and often wrong. But the weakness of our models of the world won't stop reality from coming and biting us when we make bad decisions.
It is true, that sometimes when people disagree on a political idea, that what's happened is that one person believes A (which is true) and hasn't considered B; and another person believes B (which is true) and hasn't considered A. In that case, the best thing is for both people to learn both A and B (see a "perspective [which] is not false just because it opposes yours"), and revise their plan accordingly.
But in the case of polarized opinions, what normally happens is that at least one side believes X, which isn't true, (or is a gross exaggeration). In that case, while it may help to understand where the other person is coming from, it remains the fact that the right thing is for that person to stop believing that X is true.
So take immigration. Some people claim immigrants "take jobs away" from the native population; others claim that they 1) take jobs that the natives don't want, and 2) create as many jobs as they take by being customers as well as workers. All of these individually can be true; but at the end of the day, there will be a "number of jobs" and "number of unemployed" which is a fact, and will or will not be higher. That's the number that actually counts, not these hand-wavy predictions.