An instantia is a technique to refute other's arguments, found in many tracts from the latter half of the twelfth century. An instantia has (or appears to have) the same form as the argument to be refuted and its falsity is more evident than that of the argument.Precursors of instantiae are among the teachings of masters active in the first half of the century. These masters produce counter-arguments against various inferential forms in order to examine their validity. But the aim (...) of producing counter-arguments change in the latter half of the century into refuting other's arguments to win in debate by any means available. Logicians of that period do not care whether the counter-arguments (instantiae) are sophistical or not, viz. the falsity of instantiae is or is not due to the flaw common to the argument to be refuted.Many instantiae they produce involve logical entanglements into which they themselves have little clear insight. Some instantiae and the attempts to explain them grows into the new theories in the “terminist texts” around 1200 A.D., when instantia literature itself disappears. Some instantiae and the issues they raise have no place in terminist texts, and sink into oblivion. (shrink)