Is it ethical to smoke marijuana?
Given that April 20th is just around the corner, it seems like an appropriate time to raise this issue. Several years ago, as a graduate student at the University of Colorado at Boulder, I was headed to the bus stop to go home when I encountered a flood of people coming to campus. This was unusual, given that it was late afternoon, when most people usually headed the opposite direction. Then I realized it was 4/20, and that a large number of people were coming to smoke marijuana, or at least hang out while others did, in an open grassy (no pun intended here) area on campus. I remember how strange it seemed to me that thousands of people would congregate together and smoke pot while law enforcement officers watched and did nothing. Currently the university is working to shut down the “4/20 Smoke-Out,” so that the gathering no longer occurs at CU-Boulder.
There are many arguments that have been raised for and against legalizing marijuana. I would like to focus on the morality of marijuana use, rather than the law. With that in mind, consider one reason for thinking that it's not a good idea to habitually smoke marijuana, related to Aristotle's views about human nature, ethics, and proper function. He argues that our proper function as human beings involves the use of reason. If we want to flourish as human beings, we must use reason to help us decide how we ought to live so that we cultivate virtue.
For Aristotle, there is a form of reason that is practical, which we ought to use to make choices that foster our individual well-being and contribute to the common good. This leads to true happiness, which he takes to be "activity of soul in accordance with virtue." If any activity undermines or degrades our rational capacities, then we have a moral reason to avoid that activity. (This may be a good reason to avoid all reality television as well, but I’ll leave that aside for now.) At some level of use, it does seem that marijuana has this effect on people.
This doesn't show that one should never smoke pot, nor does it entail anything about the legalization of marijuana. But it does show that there is a moral reason to avoid smoking pot that gets lost in the debates about marijuana use. If marijuana use does undermine our rational capacities, then for Aristotle it would also undercut our ability to instantiate moral virtues, which depend on the proper use of those capacities. At some level of use, Aristotle would advise us to not smoke marijuana, for the sake of our character and happiness.