parsimonia

Parsimonia is a Latin noun that forms the basis of the English term parsimony. It originally denoted thrift, economy, or frugality in the use of resources. In modern usage, parsimony describes both a disposition toward careful restraint and a methodological preference for simplicity. The adjective parsimonious is used to describe someone who is economical or a thing that is minimal in scope.

In philosophy and science, parsimony is a guiding principle rather than an absolute law. It favors explanations that achieve understanding with the fewest assumptions and the least complexity. The principle is most famously associated with Occam’s razor, which states that when faced with competing hypotheses, the simpler one should be selected if all else is equal. Parsimony serves as a heuristic to aid theory choice, model building, and inference, helping to avoid overfitting and excessive speculation.

The concept appears in several disciplines with concrete methods. In phylogenetics, parsimony methods aim to reconstruct evolutionary trees by minimizing the number of character-state changes. In statistics and machine learning, parsimony manifests as model simplicity: selecting models with fewer parameters or constrained complexity, often using information criteria such as AIC or BIC or through regularization. Information-theoretic approaches like minimum description length also embody parsimonious reasoning by balancing fit and simplicity.

Beyond scientific contexts, parsimonia describes prudent, economical living. In everyday language, parsimony can connote framed thrift and careful resource management, though excessive parsimony may be viewed negatively as miserliness.