David Nutt is a neuropsychopharmacologist specialising in the research of drugs. He is the chairman of Drug Science, a non-profit which he founded in 2010 to provide independent, evidence-based information on drugs.  He is professor of neuropharmacology at Imperial College London is a Fellow of the Royal College of Physicians, the Royal College of Psychiatrists and the Academy of Medical Scientists and was formerly the President of the European College of Neuropsychopharmacology.  He has worked closely with the UK government to provide an evidence-based approach to classifying drugs based on their harms and was famously fired for stating the facts of drug harms as they are known to science.  He has written several book on the topic, Drugs Without the Hot Air: Minimising the Harms of Legal and Illegal Drugs, Drink?: The New Science of Alcohol and Your Health and most recently Cannabis: Seeing through the smoke.  In addition to this work he has been a key figure in the revival of psychedelic research across the world. Today we discuss the harms and benefits of alcohol, cannabis & psychedelics as well as both rational and irrational approaches to drug policy.