Hickam’s Dictum

Occam’s Razor says that the simplest possible solution or answer to a problem or question is probably the correct one. In (western) medicine, this approach has helped shape how physicians diagnose patients: trying to find the simplest diagnosis that could result in the symptoms (the less complicated your theory of what the disease is, the easier it will be to test and prove it). This often results in the pursuit of the one simple answer, the one diagnosis that will have a corresponding treatment and let the doctor close the case.

Hickam’s Dictum is one doctor’s response to Occam’s Razor. Hickam saw Occam’s Razor leading to oversimplification of many complex cases, so his Dictum is often stated as:

“Patients can have as many diseases as they damn well please.”

I appreciate Hickam’s sense of humor in what is not really a fun subject (people suffering and not finding any treatment). But the Dictum is also a crucial part of developing an understanding of how ecosystems work — the ecosystems of our bodies, the ecosystems of creatures and habitats, the ecosystems of social networks… Sometimes it is appropriate (and satisfying) to find simple causal relationships between two things, but most of the time, our lives are parts of giant complex and complicated meshes. Changes cause unpredictable and non-sensical effects elsewhere. Phenomena that we witness are usually the result of a convergence of several overlapping forces, not one simple traceable event.


Hickam’s Dictum is really about the butterfly effect: it is really hard to pin down a what-caused-what map in complex systems like the human body. One small event might cause ripple effects that lead to a totally unrelated condition years later. Or set of overlapping conditions, which gets even more complicated.

There’s something really important about the difference between knowing that something may never be able to be traced to a root cause and thinking that everything happens for a simple or single reason. As we move from the 20th century into the 21st, we need to shift from diagnosis to systems thinking. The 20th century was the century of physics: we learned how the universe is structured, how chemistry works, how the building blocks of reality work, and everything became a problem to solve. We needed to feed the world, so we modified the building blocks of the food system with the Green Revolution — bam, global nutrition problems solved. We needed to end a global war quickly, so we modified the building blocks of a hydrogen atom and made a bomb — bam, world peace. We needed to treat and cure a slew of diseases, so we invented new drugs like painkillers and — bam, health problems solved.

If the 20th century was the century of physics, the 21st century is the century of ecology. We now realize that none of those one-two punches we invented with physics actually solved problems without causing ripple effects throughout the globe. We now realize that there are a lot of problems that we can’t solve with direct logical approaches. We are learning about the realities of living in a net-zero ecosystem (the globe).

September 14, 2016.

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