Joshua M. Brown quotes Charlie Munger from his 2007 USC Law commencement speech:

“Another thing I think should be avoided is extremely intense ideology because it cabbages up one’s mind. … When you’re young it’s easy to drift into loyalties and when you announce that you’re a loyal member and you start shouting the orthodox ideology out, what you’re doing is pounding it in, pounding it in, and you’re gradually ruining your mind.”

Brown underscores:

The mark of a successful investor, or at least one of the marks, is the ability to maintain two opposing thoughts in one’s head – especially these days. But if you’ve already decided what you think about every issue based purely on what your preexisting ideology demands of you, how can you possibly do that?

You can’t.

Munger is talking about life, and Brown is applying that to investing. But really, it’s an insight into how to lead a well-lived life.

It’s important to be able to wade into any ideology—any faction’s camp—and to develop an acquaintance with the people living there. It’s also important not to get lost in that camp, and to remember that the fervor and insularity of ideological approaches to the world are always examples of people living in the present, on what I’ve heard described as “the lip of history,” thinking their insights are universal whereas so many of their dead ancestor’s were simply passing fashions in comparison.