Quite. It's arguable that a person is more likely to have a dangerous encounter with a random person on the street that has a knife than such an encounter on an airplane. Watch out for all of the "artfully" concealed weapons/tools on a Swiss army knife though. Now, I'm not saying machetes, bayonets, meat cleavers, chopping knives and such should be allowed in carry on baggage, but small scissors and metal forks can be just as dangerous as a small pocket knife in nearly anybodies hands, not to mention a person trained in hand to hand fighting.