Don't treat the philosophers or views that you're discussing as if they were stupid. If
they were stupid, we wouldn't be discussing them in the first place. So even if you are
subsequently going to criticize an argument, state it first in a fair and sympathetic
manner, making clear why a reasonable person might be led to think in such a way. In
some cases, it may even be necessary to make charitable revisions to an argument. That
is, sometimes an argument is flawed in a way that can be easily fixed. In that case, you
should explain how the argument can be revised and then focus your criticisms on this
stronger, revised version of the argument. For instance, consider the following objection
against Thomson’s violinist example. Some people argue that Thomson's violinist
example isn’t analogous to pregnancy because being hooked up to the violinist for nine
months is a greater burden for the person kidnapped than pregnancy is for an expectant
mother—at least, a pregnant woman can walk around and go places, whereas the person
hooked up to the violinist is confined to a hospital bed. But it seems that Thomson could
easily revise her analogy and still use it for the same effect. After all, even if we suppose
that the violinist is very small and could be carried on one’s back for the nine months, it
still seems permissible to disconnect yourself from him.
The point is you don't want to take the weakest argument for an opposing view an
attack that. Rather you want to think of the strongest possible argument for an opposing
view and show that even that argument fails. Only then will you have convinced others
that the opposing view is indefensible.
It is important to keep in mind that it is never the case that the only problem with an
argument is that its conclusion is false. If the conclusion is false, then either (a) one or
more of its premises are false or (b) its reasoning is faulty such that the conclusion
doesn’t follow from the premises. Thus, if you disagree with the conclusion of an
argument, you must find fault with either its logic or with one of its premises, and you
need to be explicit about which it is and why.