Complex problems have multiple causes – pretending otherwise leads to failed solutions
Homelessness is caused by drug addiction.
Homelessness is caused by lack of affordable housing.
Homelessness is caused by mental illness.
All three of those claims contain real information. All three, taken alone, are wrong. Because homelessness is caused by all of those things and more, intersecting in different combinations for different people. Picking one and declaring it the cause is the single cause fallacy.
Also called causal reductionism.
The error is treating a complex phenomenon with multiple contributing factors as if it has one root explanation. It’s intellectually satisfying because simple explanations feel complete. They aren’t. They just fit in the space available, which is a different thing.
Politics runs on single-cause arguments because they fit on signs and fit in tweets.
“Poverty causes crime.” “Broken families cause poverty.” “Government dependency causes broken families.” Each of these captures something real while obscuring everything else. And each one conveniently points toward a different ideological solution, which is usually why the speaker chose that specific cause in the first place. The cause gets picked because it leads to the preferred policy, not because the evidence pointed there on its own.
School shootings generate particularly clear versions of this.
After each one, there’s an immediate argument about which single factor is responsible – access to guns, mental health services, violent video games, social isolation, parenting failures. The research consistently shows it’s an intersection of multiple factors with no single dominant cause. But “it’s complicated” doesn’t mobilize people, so single-cause narratives dominate the news cycle while the actual research sits unread.
Economic discussions have the same problem constantly.
Inflation is caused by government spending. Or supply chain disruptions. Or corporate greed. Or energy prices. Or monetary policy. Real inflation episodes involve several of these interacting at once, and the relative weight of each factor differs from one episode to the next. Attributing it to a single cause lets you blame whoever you were already inclined to blame, which is emotionally satisfying and analytically useless.
The single cause fallacy matters because it produces bad solutions.
If somebody misidentifies the cause, they design an intervention that addresses the wrong thing. Then everybody is baffled when the problem persists. Decades of failed policy responses to complex problems are basically a graveyard of single-cause solutions. Homelessness policy in particular has cycled through every single-cause fix anybody has ever proposed, and the problem hasn’t gone away because it was never a single-cause problem.
Good analysis asks different questions.
What are the necessary conditions? What are the sufficient conditions? Which factors amplify each other? Which factors become problems only when combined with others? Homelessness in San Francisco has different contributing causes than homelessness in rural Appalachia. Treating them as the same problem with the same solution guarantees that neither gets solved.
This also connects to post hoc from 15.28.
Post hoc assumes a causal relationship from sequence. Single cause fallacy assumes a causal relationship is exclusive. Both are ways of oversimplifying causation. Both produce confident claims that fall apart when the underlying system turns out to be more complicated than the story allowed for. And both do their worst damage when the person making the argument is completely sure they’re right.
Simple explanations for complex problems are almost always incomplete.
The question isn’t just what caused this. It’s which causes, in what combination, under what conditions, for which population.
That’s a harder question.
It’s also the only one worth actually asking.