  We discuss about how to make a new logic with considering a slogan: \it take
the inversion of what you know. \rm Suppose that we have a Gentzen-style
logical system $S$. The operation to make a new logic from $S$ is the
following: \it for all the axioms and rules of $S$, change the direction of all
the arrows occurred in the sequents of the axiom or the rule to the opposite
side. \rm We call this operation \it Stahlization. \rm We consider certain
logics in this respect.
