DR. BEN CARSON: I think medical use of marijuana in compassionate cases certainly has been proven to be useful. But recognize that marijuana is whatâ€™s known as a gateway drug. It tends to be a starter drug for people who move onto heavier duty drugs â€“ sometimes legal, sometimes illegal â€“ and I donâ€™t think this is something that we really want for our society. You know, weâ€™re gradually just removing all the barriers to hedonistic activity and you know, itâ€™s just, weâ€™re changing so rapidly to a different type of society and nobody is getting a chance to discuss it because, you know, itâ€™s taboo. Itâ€™s politically incorrect. Youâ€™re not supposed to talk about these things.