The safety of our citizens will be compromise if we allow knives on board our airplanes. Let us leave our knives in our kitchens, that is where they belong. Knives onboard our planes would create some uneasy feeling by passengers knowing that that their lives are stake, because the person sitting next to him/her might be carrying a knife.
A pocket knife onboard would be easily use by hijackers to command and control and take over any of our planes. Our best defense and offense: No-Knives on board.