from: Seven Tools for Thinking, as quoted by Daniel Dennett
How to compose a successful critical commentary:
1. Attempt to re-express your target's position so clearly, vividly and fairly that your target says: "Thanks, I wish I'd thought of putting it that way."
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
One immediate effect of following these rules is that your targets will be a receptive audience for your criticism: you have already shown that you understand their positions as well as they do, and have demonstrated good judgment (you agree with them on some important matters and have even been persuaded by something they said).