(b) Knowingly.Under "knowingly", (b)(i) is pretty straight forward; if it is illegal for a felon to knowingly possess a firearm and a felon knows he is possessing a firearm he satisfies that portion of the "knowingly" intent.
A person acts knowingly with respect to a material element of an offense when:
(i) if the element involves the nature of his conduct or the attendant circumstances, he is aware that his conduct is of that nature or that such circumstances exist; and
(ii) if the element involves a result of his conduct, he is aware that it is practically certain that his conduct will cause such a result.
A person acts recklessly with respect to a material element of an offense when he consciously disregards a substantial and unjustifiable risk that the material element exists or will result from his conduct. The risk must be of such a nature and degree that, considering the nature and purpose of the actor's conduct and the circumstances known to him, its disregard involves a gross deviation from the standard of conduct that a law-abiding person would observe in the actor's situation.
However, "knowingly" under (b)(ii) is the big brother of "recklessly." In other words, they are variants of the same thing. In both, the defendant has committed an act which results in a forbidden result. However, in "knowingly" doing the act it results in a "practical certainty" of an illegal result while "recklessly" doing the act only results "a substantial and unjustifiable risk" that the illegal result will occur. These are different degrees of the same thing, but with the modern aversion to actually assigning differential meanings it's doubtful that anyone will say something like "knowingly means the defendant knew to a 99% certainty that the illegal result would occur while recklessly meant he knew there was a 75% probability that the illegal result would occur."
I can understand why this could be confusing to jurors. It's the same reason that all sorts of things are confusing to jurors: because we lawyers over complicate things. I'm not sure why we need the "knowingly" intent. It seems to me that one cannot do, or omit the doing of, something purposefully without knowledge of it. The "knowingly" intent is redundant.
But, you say, what if the defendant knows he is doing something, but does not have the purpose of doing the crime? After all, someone could take Felon's wife hostage and require him to take a pistol and hide it. As well, Suspect going to jail could have been arrested with drugs secreted on her body and have it found after she is in jail and strip searched. In the first case, I would argue that Felon does purposefully possess, but that he has a powerful duress defense. In the second case, Suspect is faced with two possibilities and makes a choice: admit possession and get another charge before arriving at the jail or taking a chance that the drugs won't be found when she gets to jail. Either option is a purposeful act or omission. I am hard pressed to think of any crime where mere knowledge without a purposeful act or omission constitutes a convictable crime.
Thus, I would alter the MPC's intent section so that only Purposeful, Reckless and Negligent intents would constitute crimes. I would also add some language to the "Purposefully" section which would make it clear that both acts and omissions constitute purposeful acts and that doing or failing to do something with a knowledge that it will cause an illegal result is a purposeful act.