"We learn from those with whom we disagree"

In yesterday's Australian Frank Devine discusses the views presented by Owen Harries, who supported Australia's involvement in the Vietnam War but who has opposed its involvement in Iraq. Devine's position on each is the opposite of Harries's. Apart from the substance of the two arguments it's unusual these days to see one person criticising another's views so politely. Perhaps it's easy for me to say this because I agree with parts of what each of them says, even if I'm more inclined to agree with most of Harries's seven points (read the transcript for yourself t see them). As Devine, quoting Geoffrey Blainey, acknowledges "we learn from those with whom we disagree".