Two things in particular. In one sense, "culturally liberal" refers to the cultural milieu of self-identified liberals, that is, the culture of political liberalism. If you grew up liberal and hung out with liberals most of your life, you know what I mean - the social circle, the music, the food, the clothes, and so on. And in another sense, I'm referring to cultural pluralism - I'm carefully avoiding the term "multiculturalism", which has come into well-deserved contempt, but I do mean respect for multiple cultures in a genuine and ethically positive sense. (As opposed to the shallow, value-neutral foolishness that excuses Islamic fascism as just another "cultural expression".)
I'm bringing this up because both of these ideas will figure into my response to the much-discussed study by Robert Putnam on cultural diversity which was recently linked at The Belmont Club. As might be expected, social conservatives are reading the study's findings as a broad indictment of diversity, but I don't see it that way. I'll post more fully on it later, but I think commenter American Fool gets it right:
These results are common sense... who isn't more comfortable around like-minded people? It would be rather lonely to be the only family celebrating Christmas... or the 4th of July. On the other hand, growth derives from stepping outside of our confort zone. The point I think is that our society has, in a simplistic manner, pushed for a semi-valid "end" without appropriate discussion of the "means". I like people with different backgrounds; but I do want to watch the Superbowl with my buds... and maybe a new friend or two. And I'd like to see the World Cup with new friends that are soccer enthusiasts. That's called assimilation, and reciprocity. It's building a community. What I don't want is to be forced to watch the Tour de France in a room full of strangers from different cultures (I might on many occasions choose to do this, but I don't want it forced upon me. No matter how enthusiastic one is to experience other cultures, it is an inherently stressful experience for most people.) Multiculturalism as it has been practiced in western societies has resulted in the latter situation. It does not account for the natural distrust and fear of the unfamiliar we all experience, and that we all need a safe space to call home...
Go to the Belmont Club link for the rest of AF's comment. Also, another commenter refers us to Norm Geras for a responsible, liberal understanding of the study.