This paper examines two contrasting perspectives on morphological analysis, and considers inflectional patterns that bear on the choice between these alternatives. On what is termed an ABSTRACTIVE perspective, surface word forms are regarded as basic morphotactic units of a grammatical system, with roots, stems and exponents treated as abstractions over a lexicon of word forms. This traditional standpoint is contrasted with the more CONSTRUCTIVE perspective of post-Bloomfieldian models, in which surface word forms are ‘built’ from sub-word units. Part of the interest of this contrast is that it cuts across conventional divisions of morphological models. Thus, realization-based models are morphosyntactically ‘word-based’ in the sense that they regard words as the minimal meaningful units of a grammatical system. Yet morphotactically, these models tend to adopt a constructive ‘root-based’ or ‘stem-based’ perspective. An examination of some form-class patterns in Saami, Estonian and Georgian highlights advantages of an abstractive model, and suggests that these advantages derive from the fact that sets of words often predict other word forms and determine a morphotactic analysis of their parts, whereas sets of sub-word units are of limited predictive value and typically do not provide enough information to recover word forms.