When Hilary Putnam died recently, a common theme in the many tributes offered was his well-known willingness to change his mind. I can no longer track down the remark and so cannot quote it exactly, but I remember some place where he spoke frankly of these about-faces, strongly commending the capacity to say things in the form: "I once thought.... I now think....".
This came back to me recently while reading R.G. Collingwood's Autobiography. Collingwood is reminiscing about of John Cook Wilson, a professor of logic at Oxford:
"I rewrite, on average, one third of my logic lectures every year," said he. "That means I'm constantly changing my mind about every point in the subject. If I published, every book I wrote would betray a change of mind since the last."For Putnam, it simply meant he was willing to conduct his shifts of position in public. For Cook Wilson, it was (according to Collingwood) a reason not to publish at all. (In fact, Cook Wilson did publish -- mainly articles, many of which were collected in the posthumous Statement and Inference in 1926). There are others who fit these profiles: Socrates in the agora, (supposedly) constantly changing his position, is a model of continual public revision; Wittgenstein pruning and re-arranging the Investigations until there was no realistic chance of making them public in his lifetime is on the other extreme. But most thinkers fall somewhere between.
Collingwood remarks that
I already knew that there are two reasons why people refrain from writing books; either they are conscious that they have nothing to say, or they are conscious that they are unable to say it.For almost the first two decades after I came of age intellectually, I was haunted by the first reason. But I begin to wonder if it won't be the second that really gets me.