(1) Conduct which the actor believes to be necessary to avoid a harm or evil to himself or to another is justifiable, provided that:

    (a) the harm or evil sought to be avoided by such conduct is greater than that sought to be prevented by the law defining the offense charged;  and

    (b) neither the Code nor other law defining the offense provides exceptions or defenses dealing with the specific situation involved;  and

    (c) a legislative purpose to exclude the justification claimed does not otherwise plainly appear.

  (2) When the actor was reckless or negligent in bringing about the situation requiring a choice of harms or evils or in appraising the necessity for his conduct, the justification afforded by this Section is unavailable in a prosecution for any offense for which recklessness or negligence, as the case may be, suffices to establish culpability.