The Futility of Argument
Fichte has two arguments against argument with realists. The first is that the choice between idealism and realism is both exclusive and primordial. Everything that we could summon as a persuasive datum for making the choice betrays a prior choice: it will already be interpreted under one of the contending first principles. Alternately, since the two positions share nothing, no shared premises can justify a conclusion that both sides must accept.
Neither of these two systems can directly refute its opposite, for their quarrel is about the first principle, which admits of no derivation from anything beyond it; each of the two, if only its first principle is granted, refutes that of the other; each denies everything in its opposite, and they have no point at all in common from which they could arrive at mutual understanding. All imparting of conviction by proof presupposes...that both parties are agreed on at least something. How could the Science of Knowledge be imparted to the dogmatist, seeing that on no point whatever does it agree with him in regard to the material of our knowledge...?