I think we care for others because it is rational to do so. If you are nice to person x, they are more likely to be nice to you. By making this into a pattern, you can maintain a healthy and productive inner circle that helps you achieve your goals in life, whatever those goals are. This is how healthy communities are grown, and why certain people don’t even realize they can exist.
So, we’re not liberal because we care. We care because we’re liberal. We’re liberal because that’s actually the most beneficial way to be, for us personally. It benefits us personally, in a way that is consistent with cold, hard, logic, analyzed after we have killed the input of our feelings and emotions.
Otherwise liberalism wouldn’t even exist, because it’s difficult. Why do the difficult thing, if it’s not any better?