Language as a Stack of Homeostatic Property-Cluster Kinds: From Phonemes to Constructions

This paper develops two operational diagnostics – projectibility and homeostasis – for deciding when linguistic categories warrant treatment as homeostatic property-cluster (HPC) kinds. Projectibility asks whether a category supports reliable out-of-sample inference; homeostasis asks whether identifiable mechanisms plausibly maintain the cluster over time and across instances. I apply these diagnostics to three structural levels. At the phoneme level I use PHOIBLE inventories to show family-wise concentration of inventory sizes and a scaling relation for the front-rounded vowel /y/; at the lexical level I trace diachronic distributional neighbourhoods to show that some lexemes drift while preserving sufficient cohesion for prediction; and at the constructional level I examine \textit{let alone} to show that a small bundle of cues transfers across corpora and degrades predictably under ablation. The contribution is methodological: concrete, reproducible tests that keep kind-claims local and evidence-driven. Where both diagnostics succeed, treating a category as an HPC is empirically warranted; where they fail, a more local or descriptive account is preferable.