Perspectives
Where the optimizer Analogy Breaks
An optimizer normally has an explicit objective function. Organisms face multiple changing pressures, and evolution includes drift and migration as well as…
Calling natural selection a optimizer is useful for about five minutes. The comparison can expose structure that ordinary language hides. The problem begins when the comparison stops behaving like a tool and starts behaving like a claim about what the thing literally is.
Engineering optimization offers language for constraints, trade-offs and local improvements. Selection can resemble a blind local search using whatever variation exists.
What the metaphor gets right
Engineering optimization offers language for constraints, trade-offs and local improvements. Selection can resemble a blind local search using whatever variation exists.
This is why engineering metaphors are so attractive. They compress a complicated relationship into something we can manipulate mentally. In the best case, the metaphor produces predictions and sharper questions.
What it smuggles in
An optimizer normally has an explicit objective function. Organisms face multiple changing pressures, and evolution includes drift and migration as well as selection.
Engineering words often carry hidden assumptions: a designer, a specification, modular ownership, explicit goals, a stable machine underneath the program. Those assumptions must be tested rather than inherited.
Return to the physical story
Natural selection occurs when heritable differences affect reproductive success in a particular environment. It can make some traits more common without inspecting all possibilities or guaranteeing a global optimum.
Once the mechanism is back in view, the analogy can be kept on a short leash. We can state which relation is genuinely similar and which difference would make the analogy generate a wrong prediction.
My three tests for a metaphor
- What mechanism does this comparison help me see?
- Which engineering assumption does the natural system not share?
- What would I predict incorrectly if I took the comparison literally?
The third test is the most important. An analogy that cannot fail is decoration, not explanation.
Beyond the borrowed language
Darwin and Wallace independently recognized natural selection as a mechanism capable of explaining adaptation; population genetics later made the process mathematically precise.
Natural selection is striking because it can produce apparent purpose without anticipation.
How much apparent design can emerge from a process that never sees the final result?
A good metaphor should eventually make itself less necessary. It gets us close enough to the real system that we can see where the scaffolding ends.
Reading trail
These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.