Every distraction adds to the chance of you causing (or not avoiding) an accident. The problem with cell phones is threefold. First, having a conversation is a distraction. That by itself is not a big deal. Talking to someone sitting in the passenger seat is not seen as a bad thing typically. Cell phone is perhaps a little worse because the sound quality is worse possibly requiring increased attention to understand what the other person is trying to say. Second, the physical act of holding the phone to your ear is another distraction. Doesn't seem as though it should be, but it is. Try holding anything to your head while driving (a brick, a shoe, I don't care), and I think you'll notice it distracts you. Now you have two distractions at the same time. Third, people who talk on their cell phones do it pretty much contantly. Now you have two distractions consistently. Whereas adjusting the radio is a HUGE distraction, it also generally only happens for a few seconds each trip, and you can pick a proper time to do it, like when sitting at a red light. Not so with constant cell phone conversations. Add these all together and you have an unacceptable level of consistent distraction from your driving. Frankly, I don't think it should be illegal to talk on your cellphone while driving, but if you do it constantly, I do think it makes you a tool.