Kevin Drum comments on Matt Yglesias' suggestion that "there’s often a tendency to systematically underrate the extent to which it’s possible to change minds over time" and notes the following of public opinion:
But at its core, it's an argument that we should spend more time trying to change public opinion, and when I've talked about this in past I've found that most people (including Matt, I think) aren't really very persuaded, preferring to argue that institutional or demographic or economic forces are really all that matters. And they do matter, of course. But in the end, long-term public opinion is pretty important too, and we liberals ought to pay more attention to it. We've done a good job over the past decades moving public opinion on social issues, but not so good a job on anything else. That really needs to change.
Another way of saying this is that if a given "social issue" doesn't affect somebody's pocketbook, opinion on it will become more "liberal" over time. Even though the right wing and House Republicans are gearing up to fight the noble fight to "defend" marriage, this is not something moneyed interests are going to waste their time on (deep-pocketed evangelicals excepted, of course). Conservatives are simply on the wrong side of history but either sincerely believe civilization is in peril or are pandering to their base. Moreover, public opinion on non-social issues already largely favors liberal positions. The public loves their Medicare and Social Security. The public would love to increase taxes on the wealthy. Open-ended, pointless, and costly wars are not favored. Hell, even employees in public unions turned out to be popular.
So I'm not convinced that there is all that much point in trying to mold public opinion, especially when decisive political action gets better results. Public opinion isn't responsible for our failure to enact meaningful climate change legislation. The structure of the U.S. Senate is. And lo and behold, in bad economic times, skepticism about climate change has risen, aided by deep-pocketed interests opposed to tackling it. Besides, even if public opinion is on your side on specific policy issues, this does not necessarily reflect a coherent worldview that is broadly sympathetic to your own ideological leanings. The same public that's on your side for reducing dependency on foreign oil thinks foreign aid is responsible for the deficit.
It's not that liberals shouldn't be making the case for social progress and economic justice. It's just that I'd rather see political parties that take clear policy positions and then fight like hell for them. It's much easier to make the claim that the public is on your side when the parties offer a clean contrast with one another.