Faced with rival explanations that fit equally well, prefer the simpler. This ancient counsel is not mere taste; simpler theories tend to generalize better and to be more likely true. Parsimony is a working principle, not a prejudice.
The core idea
Occam’s razor advises choosing the simplest hypothesis consistent with the evidence. Among explanations that account for the data, the least elaborate is preferred. Complexity should not be multiplied without need.
Why it holds
The justification is more than aesthetic. Simpler hypotheses make sharper predictions and are less able to accommodate noise, so when they fit, the fit is more meaningful. Simplicity is evidence-efficient.
A deeper reading
The turn is that the razor is itself a prior. To prefer simplicity is to assume the world is simple, an assumption that can be made precise and can be wrong. The blade cuts on a bet.
The tension within
Applied carelessly, it misleads. What counts as simple depends on description, and a genuinely complex truth punishes the seeker of simplicity. The razor is a guide, not a guarantee.
Where it fails
The implication is that theory choice is inference, not just accounting. Preferring simplicity is a considered bet about how the world is built. It usually pays, but not always.
The larger point
Occam’s razor prefers the simplest adequate explanation, justified because simplicity resists noise and sharpens prediction. It is a prior, a bet that the world is simple, and can err. Parsimony is a principled wager, not a mere taste. The principle rewards the patience to state it precisely and the humility to mark its limits. Precision reveals what it truly claims; humility reveals where it quietly fails. Between these two disciplines lies genuine understanding, which is never the possession of a conclusion but the grasp of why the conclusion holds and exactly how far it reaches.
