Correlation Without Entailment: Atheism and Marijuana Legalization
On an episode of The Atheist Experience, Matt Dillahunty was asked whether atheism has anything to do with support for marijuana legalization. He said no — the two are unrelated.
Formally he is right. Atheism is the absence of belief in gods. It entails nothing whatever about drug policy, and you can construct a perfectly coherent atheist prohibitionist.
But I think the answer is wrong anyway, and how it is wrong is worth working out, because the same mistake appears in a great many arguments.
The Correlation Is Real
There is almost certainly a strong correlation. If you surveyed atheists and the general population on legalization, I would expect a substantial gap.
So we have two claims that both seem true:
- The positions are logically unrelated.
- The positions are strongly correlated.
Dillahunty's answer asserts the first and, by implication, denies the second. That is where it goes wrong — not by being false, but by answering a question about the world with a fact about definitions.
The Resolution
Neither position causes the other. Nobody reasons from the non-existence of gods to a conclusion about cannabis.
They are both downstream of a shared upstream commitment that mentions neither. The obvious candidate is a disposition to take evidence seriously.
Take evidence seriously and you tend toward atheism, because the evidence for gods is poor. Take evidence seriously and you also notice that prohibition has failed on its own terms — it has not eliminated use, it has produced a large criminal economy, and the comparative data from jurisdictions that liberalised do not show the predicted catastrophes.
Two conclusions, one root. The correlation is entirely real and the logical independence is entirely real, and there is no tension between them once you see that a common cause is doing the work.
Why the Formal Answer Is Inadequate
"They're unrelated" is true of the definitions and false of the people. And it is the people we were being asked about.
The questioner was not asking whether atheism logically entails a drug policy. He was asking why atheists seem to cluster on this issue — a question about the world, with a real and interesting answer.
Retreating to the definitional claim leaves that question unanswered while sounding as though it has been settled. It is the kind of correct-but-useless reply that gives careful thinking a bad name.
The General Pattern
This is worth having as a standing tool, because the shape recurs constantly.
Positions cluster not because they imply one another but because they share a root. Political packages work like this, which is why they are so hard to argue with piecemeal — the individual positions look arbitrary in combination, and become intelligible only when you find the disposition generating them.
The practical upshot: when you find a correlation between positions that do not entail each other, do not dismiss it as coincidence and do not invent a causal link between them. Look upstream. The interesting object is the shared commitment, and it is usually more revealing than either position it produced.
Dismissing the correlation on definitional grounds explains nothing and forecloses the search. It is the right answer to a question nobody asked.