There are seven 'Disagreement Hierarchy' levels from the worst method to the best.
DH1. Ad Hominem.
DH2. Responding to Tone.
DH6. Refuting the Central Point.
I guess its probably unproductive to do anything below level 4.
And level 6 is best. Here is what is said about level 6.
The force of a refutation depends on what you refute. The most powerful form of disagreement is to refute someone's central point.
Even as high as DH5 we still sometimes see deliberate dishonesty, as when someone picks out minor points of an argument and refutes those. Sometimes the spirit in which this is done makes it more of a sophisticated form of ad hominem than actual refutation. For example, correcting someone's grammar, or harping on minor mistakes in names or numbers. Unless the opposing argument actually depends on such things, the only purpose of correcting them is to discredit one's opponent.
Truly refuting something requires one to refute its central point, or at least one of them. And that means one has to commit explicitly to what the central point is. So a truly effective refutation would look like:
The author's main point seems to be x. As he says:
But this is wrong for the following reasons...
The quotation you point out as mistaken need not be the actual statement of the author's main point. It's enough to refute something it depends upon.
However, is it productive even to disagree at all??? Of course, avoiding disagreement maybe looks aloof, but disagreeing is often extremely time consuming and doesn't necessarily create positive alternatives. Disagreeing in detail often requires an obsession to a task which may be unhealthy.
Anyway, I have the following summary:
- Spend time understanding the central point of your interlocutor
- Paraphrase this point and even comment yourself. If you have the time to read something, you have the time to comment on it
- Suggest positive arguments yourself in the area that really matters, although not necessarily in the same post
There is a danger of all of this 'directed' advice, that danger is that your interlocutor may see this as a 'war' and this war will induce an 'arms race'. You need to move to a more cooperative state; or at least a state where there is some degree of cooperation over shared goals or rules of the game. In general, we need to focus not on how to win the argument, but on the arguments themselves. Truth and reasonableness are higher goals than momentary victory.