One of my pet theories is that only actions in which their is a potential for really bad consequences also have the potential for really good consequences. Take judicial power. I am a supporter of judicial interventionism. I recognize that this could potentially lead to catastrophically bad results (e.g., Dred Scott). But I see it as the only way to lead to good/right results. That is to say, a non-interventionist approach, to me, is a guarantee of moderate suckiness. The same discretion that enables wildly unjust results also unlocks the potential for achieving just results. Since I want to preserve the potential for justice in the system, I support judicial power, but keep a careful eye on it to make sure it's being used for good and not evil (I recognize that these are hotly disputed terms, but that's a subject for another post). Similarly, Ian F. Haney Lopez observed that any use of race conscious thinking could theoretically be perverted to racist ends, but if we're serious about ending racism, race conscious thinking is absolutely necessary, so that's a risk we're going to have to take. Focusing solely on when it goes wrong means foreclosing the only options that offer the chance of getting things right.
An interesting example of this is Connecticut Senator Joe Lieberman, the Democrat most hated by Democrats this side of Zell Miller. I'm kind of ambivalent to old Joe. On one hand, he's been far too willing to defend really bad government policies, serving as a GOP foil to legitimate Democratic attacks on the Bush administration. I think the charges of "Fox News Democrat" are overstated, but not completely drawn from whole cloth either. I'm certainly less of a fan than I was even a few years ago. If The New Republic was revisiting its presidential endorsement issue from 2004, I'd expect and hope that they would not give it to Lieberman (of course, I supported Clark in 2004).
On the other hand, the same maverick streak that places Joe on the side of Bush on issues I'd rather he'd not be, also means that he's been ahead of the curve on a bunch of issues I'd like the Democratic party to push harder on. The Department of Homeland Security? His idea. And in general, Lieberman's constant press for more security funding has been superb. So all in all, I'm willing to overlook, if not forgive, Lieberman's flaws as a politician. I don't support the primary campaign in Connecticut to knock Lieberman out of office (and it's not based off a generic opposition to challenging one's own incumbents--I support Ciro Rodriguez's effort to take back his seat from Henry Cuellar). The attributes that make him sometimes do really dumb things also sometimes make him do really awesome things--I want to preserve that.
I look at Lieberman and see a flawed but ultimately defensible politician. Sure, when he's wrong, he's wrong in a much bigger way than Senator Mainstream Democrat. But on the other hand, he's right bigger too. One can debate about where we should draw the line--but I think it's unfair to cast Lieberman as some sort of uniquely evil man. So when someone makes a Nazi analogy to Joe, calling him "Herr Lieberman", I think that crosses a very serious line. Godwin's Law aside, I blogged specifically on why, in "ordinary political disputes" (which, for better or worse, the anti-Lieberman campaign is), ethnic slurs (by which I mean epithets designed to have particular potency based on the target's race, religion, or background) should be considered out of bounds. See the linked post for the full argument, but implicitly comparing a Jew to a Nazi obviously qualifies--even if one doesn't think that Nazi comparisons are per se wrong, it's qualitatively different when one does it to a Jew because of their unique history. That it was endorsed by one of the more popular liberal blogs on the web is even more distressing, and shows an inability of some persons to divide between political opposition and personal slurs (H/T: The Plank).
Of course, like the proverbial coin that flips tails fifty times in a row, there are those people whose "maverick" streak causes them to be consistently, extremely, and transcendentally wrong on almost every issue. Cindy Sheehan jumps immediately to mind. Even though we both identify as progressives, she still manages to take that value system and morph it into complete idiocy. I probably feel about Sheehan what many people feel about Lieberman (of course, I think I'm right and they're wrong, but whatever), but I'm not going to engage in any sort of "hate speech" against her (calling her a "bitch" or "pseudo-Stalinist pinko" or however one puts down a white female leftist these days). I'll just keep on saying that I think Sheehan is clearly, completely, indisputably wrong about nearly every issue she opens her mouth about. Despite what the right would like, that doesn't make me question progressivism inherently. It just reminds me that any good theory (like progressivism) has the potential to be used for evil. If it doesn't, then it likely isn't flexible enough to actually be a good theory.
So to recap: strong theories will inherently risk being wrong big sometimes (Lieberman) or even all the time (Sheehan). But that isn't, by itself, a reason to reject the theory. It's just a reason to be more vigilant in its application.