There’s a good rule of thumb in evaluating your own beliefs that if there is NOTHING that you say would change your mind on something, then you are not thinking well. It’s important to recognize the limits of our beliefs and make sure we establish the guardrails that will help us from running off the cliff like the GOP after Trump.
I think the same must be for our character. It’s important for us to have people that we say “If this person thinks what I’m doing or saying is wrong, then I need to reevaluate.” This could be good friends, life partners, family members, etc.
I think most people have this part down pretty well, actually. What I think we tend to do, however, is find people so much like us that the feedback is easy. And we need these people! People who are going in the same direction we are, aiming at the same goal, using similar methods (have very similar ethics, that is). It’s much harder to be close to people who do not share our ideologies and then take seriously the challenges they present to us in our behaviors.
I have several friends who are very different from me, but very similar to how I used to be. Aka, they are committed to being in a Christian community and instilling biblical verses deep in their subconscious. I disagree with this with almost everything in me. BUT I believe these friends are deeply good people who care about others. So I listen to why they do what they do and I consider their advice. I even accept that there are goods to be found in the communities they put themselves in. Depending on the person (and the specific things I respect and admire about them), I would consider their advice on parenthood, relationships, professional goals, anxiety, fitness, books to read (if I read a book you recommend, you should feel VERY VERY honored), and critiques on my philosophy papers and ideas.
We have this tendency to “chunk” our ethics. We think that every good person must have this particular set of characteristics, and that certain virtues must always attend the whole set of what we happen to find valuable (valuable because it is what we aspire to be or are proud to be ourselves). A problematic person cannot be sincerely kind, or a liberal cannot be patient, or a conservative cannot be compassionate. We believe these things because we like things in black and white, and the world is so rarely that clear cut. People certainly are not clear-cut (at least in most ways). Finding good people who challenge our beliefs about what “good” looks like can be one of the best correctives for our biases. Looking specifically for the thing that would change our minds about what good looks like can enrich our lives in ways we would never be able to imagine on our own, and make us much better people in general.