I think that humility promotes understanding, and so promotes wise judging. Some years back Brett Scharffs argued this point at length and with eloquence, in "The Role of Humility in Exercising Practical Wisdom," 32 U.C. Davis L. Rev. 127 (1998). But he acknowledges that "[o]ne might question whether, as a matter of historical or contemporaneous fact, the judges we consider great were or are humble." (At 171 n.108.) Later he discusses Justice Holmes, who on occasion was credited with a form of humility, but also (according to a scholar named Yosal Rogat) described "his work on the Court as 'preparing small diamonds for people of limited intellectual means.' In a humility contest, Rogat concluded, Holmes would 'tie for last with General DeGaulle.'" (At 185-86 n. 148, quoting Thomas C. Grey, "Unrepeatable Lessons," 70 N.Y. U. L. Rev. 524, 527 (1995).)
Scharffs rightly suggests that perhaps some judges we don't think of as humble actually were so, at least in their work as judges, and also that some judges who aren't humble no doubt are, in part for that very reason, not admirable judges. Still, he does not go so far as to reject the possibility that great judges typically are not humble people.
One might accept this possibility as fact, and still say that humility is an integral virtue for judging in general. The argument would be that most people are better judges if they bring humility to their work, even though great judges may have such stunning strengths in other respects that their lack of humility isn't a fatal flaw.
One might also say that "greatness" is itself a treacherous quality. Prideful greatness, after all, is essentially hubris, the pride that goeth before a tragic fall. Great judges are not necessarily the best judges for a country to have. They surely are prone to failing, as well as succeeding, greatly -- and while such stories make for great dramas, they probably aren't so good for the citizens living with the results.
But I think there is another possibility which may be more disturbing even than these. This is that it takes so much self-confidence to render decisions that determine other people's fate that for many people pride is simply essential to getting the job done. There are exceptions, undoubtedly -- apparently, as Scharffs also notes, Learned Hand was never sure of anything, though it is tempting to think that this self-doubt contributed to the "legendary temper" that he apparently also displayed. (Scharffs at 197 n.180, 195 n.176). But for most people, the thought of having ruled against someone -- taking that person's money, or liberty, or life -- in error may be very hard to take. (Scharffs points to Robert Cover's emphasis on the violence that is integral to the workings of the law; the anguish of decision may be even greater because of the recognition that litigants do not consent to their suffering, as patients may, but rather are coerced into enduring it.) Doctors have to develop a certain armor against their patients' suffering, as do lawyers, and so, similarly, may judges, and their armor may often be a confidence, a disproportionate confidence, that their decisions were right. If that is so, then although humility may be a great asset for wise decisionmaking, it may be crowded out by pride, a quality that may be a solace, if not a necessity, for any decisionmaking at all.
If pride is such a necessity, the best hope for those who see humility as also valuable is to make the case that people can possess both pride and humility at the same time. I doubt that that is easy, but I think it is possible. Scharffs' ideal of humility may be quite intensely selfless; he quotes C.S. Lewis, who wrote that "a really humble man" is someone who will take "a real interest in what you said to him. If you dislike him it will be because you feel a little envious of anyone who seems to enjoy life so easily. He will not be thinking about humility: he will be thinking about himself at all." (At 162 n.92, quoting C.S. Lewis, Mere Christianity 99 (1965))
But one can imagine people, and judges, whose ability to engage deeply with the perspectives of those before them is not quite so unselfconscious. A judge who takes pride is in his or her ability to listen and understand (and who in fact has and uses that ability) may not be quite so saintly as Lewis' ideal. But this judge is more likely in fact to exist, and we are very fortunate when we have him or her on the bench.