I've just had my 'don't know what I think until I read what I've written' line tested successfully. I read an article in a newspaper, got a bit annoyed about it, and started writing a post about why the author was wrong to say what he did.
In constructing my arguments, I couldn't articulate anything better than the offending article. OK, I don't think he would have argued his case (the one that I now agree with) in the same way that I do, but I'm forced to admit that he was right all along. OK - he should have been a good deal more dismissive of the very idea of group rights, and he should have explained why the encouragement of anti-democratic violence elsewhere is not compatible with liberal democracy here.
But, as I say, he was broadly right to say what he did. And that I've just wasted best part of an hour.