Deriving variation from grammar: A study of Finnish genitives

A way to derive morphological variation from UG principles is proposed. The speci c problem discussed is the variable in ectional behavior of polysyllabic nouns in Finnish. An example is naapuri-gen-pl `neighbor' which has several surface variants, including naapurien and naapureiden. Building on Optimality Theory, I construct a grammar which predicts in what circumstances variation may and may not occur and which variant is preferred. Categorical outputs, variable outputs and statistical preferences follow from syllable prominence de ned as a combination of stress, weight and sonority. Variation depends on how successfully these properties harmonize. If a stem gives rise to one very harmonic form, it shows no variation; if it yields several almost equioptimal alternatives, variation arises. Both categorical cases and variation are derived from one partially ranked grammar which yields multiple totally ranked tableaux. The number of total rankings by which a variant wins predicts its probability of occurrence.