A real disagreement over politics is almost never about the goals themselves. It's almost always about either methods, priorities, or both. What means will really achieve this or that goal? And, on which of these goals should we put the strongest focus? One person (usually speaking on behalf of some team who they root for, whose aims they believe in and whose strategies they agree with) believes X goal is most important for human benefit - but you may be sure that the other side is also arguing hard for human benefit! They just don't believe X is the most important component we need, to move towards it. They think K is the most important component. Or maybe they say it's a balance, that we need X and K, but that B is more important than either of them, and if we go deeper we'll see we need a suite of other things besides. But good news! They say: if only we follow This Route, "it's all going to be achievable!"
Now this doesn't sit well with you at all. First of all, X is way more important than those other things, even if you agree those are good things. But secondly, you dispute that That Route is even the best way to get there! Even if that's where you're trying to get, you could think of two other better ways, which of course you don't advocate either. Because again, X is what we should be focusing on, not these other things. It's undeniable that we NEED X - how can anyone ignore or dispute it? To dispute it, why, they must be a BAD PERSON right? They'd have to be a bad person to be against X, it's just too obvious. All these other things will be helpful as well, but Good News! You'll see that if you focus on X, many other goods will follow in its wake. And great news, you say: we know how to get X, here's the method we've been pounding home. We need to do this.
To which the other person chimes in, no, I don't agree with you. I don't think your method will do what you say it will (get X), I think you're ignoring some of the bad consequence that will follow from your method, and I still don't think getting X is the real solution here. Also, I really don't appreciate you calling me out, implying that I must be a bad person - how dare you dismiss my commitment, devalue my experience and marginalize my oh no there it went.
Let's just...step back a sec, to catch sight of why both of these people are willing to argue so passionately, even to the point of ruining relations with someone. It is because they are both almost fanatically in favor of human benefit. Of doing things the best way to get people's suffering diminished and their needs managed, while to the greatest extent possible, freeing people's lives from fear of tyranny, and freeing their minds from whatever keeps them from seeing or seeking happiness. BOTH people want ALL THAT most, most, most.
And so at its every point, their conversation becomes a process of losing sight of that biggest goal, in a disagreement over priorities and methods. Priorities: because resources are finite. We need to put our strength where it gets the most and best goods. Which good things do we most need to stress? What bad things are risked - and which risks are most important to manage? Methods: because not all plans work as advertised. Not all plans even appear to be designed to do what they say they will do. We need to question, pick holes, suggest alternatives. Our two disputants disagree on priorities and on methods, because they do both want to get there. Human benefit. Where almost always, they both have a shockingly similar idea of what that is. You could put it in a very old school way: freedom from want. Freedom from fear. A world within which people are free to pursue happiness. Pretty much the whole disagreement is over different ways to get there, and which is most important to stress.
Yet despite their quite lofty and shared aims, and despite their deep commitment, both of these people are probably going to walk away from this conversation complaining "that other person's an ogre. A bigot. A moron," for not seeing their way my way. Both people will probably walk away saying the other is intolerant, dismissive of my person! - for the ways they each find to subtly imply the other has to be stupid to believe as they do. An uncompassionate person, an apathetic person for not caring enough to see the way it CLEARLY needs to be done. A fascist, or fascist sympathizer - whether the accuser thinks the capitalists or the socialists are the real fascists doesn't really matter, "a tyrant" would be a better word. Someone who wants others to be under their control, or under the control of how they think things be. Some way, any way, based on this or that turn of the conversation, both these people will probably walk away having found a way to dismiss the other as just a BAD PERSON.
And these are people who both, as I noted above, are almost fanatically committed to human benefit. They are both very deeply committed to it. Now I say "almost fanatical," not "fanatical." Neither of these people walks around fanatical. None of their friends would ever say they were fanatics. Neither of them will probably even bring up the topic, unless it comes up - but if it does, they won't shirk. They care, they know what's right and what needs to be done, and they won't shrink from speaking out about it! For the most part, with calm confidence, reasonably, and listing to the other's take as well. Mostly because they expect and know they can refute it, OK, but the point is they do listen. These two would never normally be fanatical about what they believe, under normal conditions. It takes a certain heightened circumstance to get them to escalate from a passionate "almost" to spitting, indignant fanaticism.
Sometimes, all that circumstance has to be is running up against another calm, reasonable, seemingly-intelligent person. Instead of making it easy for you by being the cretin you'd expect would believe a thing like that, this reasonable person inexplicably, impossibly believes the The Stance You Can't Stand. Listens to you and hears you out, but says they can't see it your way, and further, lays out why they say they can't - and it's That Stance You Can't Stand. The one you know back to front, and have a million ways it's wrong, and you trot these out! Smiling, probably - you know you're right, and what can they say to gainsay all these ways you know their stance is wrong? And they keep responding, and making points, and it just suddenly dawns on you that maybe there is a way that even a reasonable person, an intelligent person, can advocate this. And that's when you go ape. You can't accept that. You can't accept the stance whose hordes of faceless abstract adherents you casually revile can be valid for a reasonable human being to believe. A reasonable human being would share your priorities on this. You're pretty sure!
You know the kind of stance I'm talking about. You walk around telling yourself: how can anyone believe that? There's no way anyone believes that, except if they're a moron. Or the other way, if they're actually one of the "bad guys." That's your demographic breakdown of the opposition, in your mind: mostly morons, but controlled and whipped up by a few bad guys, masterminds, fanatic champions, what have you - who drive and exploit the great mass of sheep: the uneducated, the indoctrinated, the just plain ignorant, for the benefit of that nasty agenda. Because no one who is both intelligent and sincerely interested in good could believe That Stance is a good one, if they just looked at it! If they were intelligent and sincerely looked at it from all sides, they'd believe my stance then.
I can't accept you can believe in that stance and be a decent and passionately good, intelligent individual. To believe in The Stance I Can't Stand, you can only be either a dumb sheep or an active agent of evil. Either you're The Ignorant, too ignorant to see how obviously wrong your stance is, or...you must be In On It. You must be the bad guys. In which case you do know your stance is wrong, but you dress it up for the world in your drive to control and get people to conform, you want to oppress and wield power. You must be an agent of deliberate oppression: racial oppression, or sexual oppression, or economic oppression, or religious oppression, or military oppression. You must either be that, or a plain moron to believe that stance, I'm telling you.
See, that's the big breakdown. All these people, all on different sides of the same issues, all telling themselves that human good is CLEARLY best served by their stance, and that all the other people, who believe their b.s. stance (which let me tell you I know back-to-front and can refute standing on my head) are either fools who've been fooled, or the clever fiends who fool them.
If they weren't all such simpleton ignoramuses, you'd think a couple steps back and one good look at it would tell them that hey, all we have here really with these battling stances of ours are just some relatively small disagreements over points of emphasis. Over priorities, and methods.