Fundamentally, all ideals are based on ethics. If you go back up the chain underlying assumptions behind everyone's actions and convictions, you will find things like "I think that people dying of hunger isn't great" or "I think that torturing the innocent is bad". On some level basic empathy is natural, as well as a desire to live in a world where people don't have to feel afraid constantly.
Of course being able to debate things is important and leads people to changing their positions on certain issues (see my previous example with Waymar accepting sacrifice because we framed it as something that didn't clash with his fundamental beliefs), but the fundamental underpinnings of people's convictions aren't reasonable.
Otherwise, why would empathy and altruism be a thing? Why would people care about famines in Africa, when they clearly don't affect us in any way? Why would people do things that benefit others at cost to themselves?
Now you could argue that they do this because it brings them satisfaction, but I'm unconvinced. Would people really put their lives in danger rescuing flood victims and whatnot just for personal satisfaction?
My post was literally arguing that deeply-held ideals are fundamentally irrational, so yes. There are people out there who argue that killing all infidels is a good thing. I'm not going to reason that with them, nor will I be convinced that their ideals are morally correct and that I should adopt them.
Therefore yes there are good ideals and bad ideals, and in my opinion good ideals are my ideals and bad opinions are those opposed to mine. Of course not everything is an ideal: my political opinions may change during my lifetime, as the situation changes and people convince me that the best way to apply those ideals isn't what I thought it was.
But
@Azel, fundamentally everyone seems to share basic ideals. What group or party doesn't agree about basic ethical principles? Things like "don't murder people", "it's better if everyone is happy" and "basic security is nice". Of course people don't agree about how to enact this (what is "basic security" ? Should we have social security to make everyone happy, or is that crippling society and the economy and eventually removing basic security and happiness by leading us to collapse ? Is it murder to lynch a lesbian, or is it defending our daughters against the irredeemable?). Maybe such ideals are stupid and naïve, but most people have them. And even getting people to do immoral things that directly benefits them often requires re-framing it and convincing people so that it doesn't clash with these ideals.
I dunno. I think that having ideals you stick to can be a good thing. It makes it harder for you to be swayed towards doing horrible things through fear or coercion. Of course it's important to be willing to talk them though and debate, and to be open to being convinced that in a specific situation it's necessary to do something that you normally wouldn't. But convincing you should be hard, and will require persuading you not only that something is a reasonable choice but also that it will eventually further your ideals in the long run, even if it means its necessary to accept "bad things" in the short term.
EDIT: I also believe that these basic ideals I think most people have are also reasonably correct, and that if you think things through we'll all agree that living in a world that isn't "dog eat dog" all the time is better for everyone (although we may disagree on the exact shape that the world should take and on how our different beliefs should interact with each other). But people don't think things through like that, do they?