Bill argues that addiction is a disease by using scientific instruments to show that the part of the brain responsible for weighing actions against consequences does not function properly when one is addicted to drugs. Bill also shows that part of getting drunk is largely a placebo effect, by letting a group of people drink beer without them knowing it is non-alcoholic. Finally, a theory is presented as to why the part of the brain responsible for making us addicted to things has not faded away over time.