Good advice on how to treat those who disagree with you

From Greg Mankiw:

I have found that to convince other people, it is usually best not to assume your own moral superiority but rather to talk with them as equals who just happen to have a different point of view.

He also addresses a logical fallacy.

After the first session was over, one of the hecklers came up to me and asked, “How much money have the Koch brothers paid you?”

If I am wrong, it is sincere wrong-headedness, not the result of being on some plutocrat’s payroll, as some on the left want to believe.

I agree.  Address the argument, not the motives. But I’m not so sure about this:

The hecklers probably limit their own effectiveness by questioning the motives of those who disagree with them.

I think they have found that tactic works extremely well to gain acceptance with those who hold similar views. It may also work well to convert those who are on the fence and searching for an easy excuse to decide one way or the other.

And, unfortunately, it’s an effective defense mechanism that prevents the hecklers themselves from evaluating the issue.