Twitter reminds me of this 2006 post, which I linked at the time: On Morality,
written by an ethicist in an attempt to provide a primer on moral thinking for those liberals who might be squeamish about making moral judgements.
There is a straightforward moral case to be made not just against the current crop of Republican politicians, but also, I think, for liberal values. But as long as we cede moral language to conservatives, we will not be able to make this case effectively. Nor will we be able to speak to the legitimate fears of people who (correctly) think that morality is extremely important, who are worried that it's under seige, and who (mistakenly) suppose that only conservatives are willing to speak up for them, or that defending morality involves an obsession with preventing gay marriage, or something like that. [...]
We all perform actions. And whether or not we reflect on the kinds of actions we think we should perform ... we will end up performing some actions and not others, living in accordance with certain principles, and developing a particular character. It will be true of one person that she ruthlessly pursues her own interests; of another that she drifts along, allowing her actions to be determined by the preferences of those around her; of another that she tries to preserve her image of herself as 'virtuous' only as long as it is not too inconvenient to do so; and of another that she tries to respond to others with generosity and honesty and respect, even when this is difficult. [...]
This being the case, it makes sense to try to figure out which principles we think should try to live by and which sorts of persons we think we should try to be.