The most difficult problems in criminal theory are generated by dissonance between reality and belief, between the objective facts and the actor's subjective impression of the facts. In Chapter Seven we explored the implications of the facts being innocent, but the actor's beliefs being criminal. Now we turn to the vast set of problems connected with the facts being incriminating, but the actor's beliefs, innocent. This is the general problem of mistake and ignorance about conduct that nominally violates a legal prohibition. If the actor knows of the circumstances in these cases, he surely would be liable for his conduct; but if he does not know, we confront the general theoretical question about the extent to which his ignorance provides an excuse for his legal violation.
Our discussion will begin by categorizing the various types of mistakes that might arise in criminal proceedings; we shall then consider three postures toward mistakes and their implications, and finally we shall assess strategies and arguments both for ac-