Rhetorical dishonesties and their countermeasures

Here's a list of "Thirty-eight dishonest tricks which are commonly used in argument, with the methods of overcoming them."

(8) The argument that we should not make efforts against X which is admittedly evil because there is a worse evil Y against which our efforts should be directed (pp 50-52)

Dealt with by pointing out that this is a reason for making efforts to abolish Y, but no reason for not also making efforts to get rid of X.

(9) The recommendation of a position because it is a mean between two extremes (pp 52-54)

Dealt with by denying the usefulness of the principle as a method of discovering the truth. In practice, this can most easily be done by showing that our own view also can be represented as a mean between two extremes.

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(via Making Light)