Everything we do is for the purpose of altering consciousness. We form friendships so that we can feel certain emotions, like love, and avoid others, like loneliness. We eat specific foods to enjoy their fleeting presence on our tongues. We read for the pleasure of thinking another person’s thoughts. Every waking moment—and even in our dreams—we struggle to direct the flow of sensation, emotion, and cognition toward states of consciousness that we value.

Drugs are another means toward this end. Some are illegal; some are stigmatized; some are dangerous—though, perversely, these sets only partially intersect. There are drugs of extraordinary power and utility, like psilocybin (the active compound in “magic mushrooms”) and lysergic acid diethylamide (LSD), which pose no apparent risk of addiction and are physically well-tolerated, and yet one can still be sent to prison for their use—while drugs like tobacco and alcohol, which have ruined countless lives, are enjoyed ad libitum in almost every society on earth. There are other points on this continuum—3,4-methylene-dioxy-N-methylamphetamine (MDMA or “Ecstasy”) has remarkable therapeutic potential, but it is also susceptible to abuse, and there is some evidence that it can be neurotoxic.

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