Thanks for pointing this out. I missed this among Xianhang Zhang's posts. He's in good company.

The answer to your question actually lies in Isaiah Berlin's Hedgehog-Fox distinction, riffing on the Greek philosopher Archilocus. This is similar, but subtly different, from Hang's model. A refactoring of sorts.

http://en.wikipedia.org/wiki/The...

Hang's one-thing/many-things distinction, at zeroth order, is basically the hedgehog/fox distinction. More precisely, you can map Philosopher Hang to Philosopher Archilocus as follows: Hang's "single passion" people contains both natural-born hedgehogs, and "converted foxes." His "multiple passion people" contains both hedgehogs with a single meta-passion, and looser right-brained foxes.

Hang's classification leaves out true "foxes"... people who are interested in tons of things without really going meta over connections etc. In a way, these are truer "Berlin" foxes, and I believe this type does exist, though Hang suspects it might be an empty set.

Natural-born hedgehogs are Hang's basic "one, non-meta thing" people. They are not narrow, but they see the world through their one lens. A great example is biologist George Wald, described by Rachel Carson in Silent Spring:

THE BIOLOGIST George Wald once compared his work on an exceedingly specialized subject, the visual pigments of the eye, to "a very narrow window through which at a distance one can see only a crack of light. As one comes closer the view grows wider and wider, until finally through this same narrow window one is looking at the universe."

But converted foxes are way more interesting. Foxes can "convert" in two ways:

First they can "focus" on one non-meta thing. It is rare, but it can happen. The best example I can think of is perhaps Edward Witten, Superstring theory pioneer, who was actually a poli-sci major as an undergrad and wrote articles for Foreign Policy. His work was more math than physics, but it is still "focused" in the same way Wald's work was.

Second, they can "focus" on a single "meta-thing" that turns their right-brained meandering into hedgehog-like unifying passion. Hegel with his self/other and master/slave type ideas might be a good example.

But to me the most interesting is people who, despite severe temptation, refuse to give up true fox-hood. Nietzsche is the best example. He could have easily turned hedgehog over "individualism" (degenerating into an Ayn Rand) or meta-hedgehog over a unifying meta-concept like "creative destruction." He chose to do neither, but remained an elusive, dancing trickster all his life.