Now a person cannot perform the least reasoning without some general ideal of good reasoning; for reasoning involves deliberate approval of one’s reasoning; and approval cannot be deliberate unless it is based upon the comparison of the thing approved with some idea of how such a thing ought to appear. Every reasoner, then, has some general idea of what good reasoning is. This constitutes a theory of logic: the scholastics called it the reasoner’s logica utens. Every reasoner whose attention has been considerably drawn to his inner life must soon become aware of this.
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