This post is from a few years ago, but Bob Sutton blogged about the idea that one should have strong opinions, weakly held. From the post:
…weak opinions are problematic because people aren’t inspired to develop the best arguments possible for them, or to put forth the energy required to test them.
But at the same time:
…(it is) just as important, however, to not be too attached to what you believe because, otherwise, it undermines your ability to “see” and “hear” evidence that clashes with your opinions. This is what psychologists sometimes call the problem of “confirmation bias.”
Now, I wouldn’t go as far as Sutton does in tying this notion to the concept of wisdom, but you can see in all walks of life and just about every field of endeavor where not following this behavior can lead to problems. As I’ve blogged about previously and use as a common example, Agile fanatics seem to fall prey to confirmation bias all the time (“I tried Agile techniques on this project and it failed”…”Well, then you weren’t really doing Agile”), and it is also seems pretty common when it comes to unit testing and TDD, where even the possibility that unit testing might not be useful in some contexts boggles some minds. Which is silly, and really unnecessary. If unit testing helps (making up a number) 87% of the time, then you are still better off doing it, most of the time. Refusing to acknowledge counter-examples just makes one look foolish.
There are, of course, times when the proper course to take is of having strong opinions, strongly held, but it is generally good advice to consider following the path of strong opinions, weakly held.