Most probabilistic analyses of choice are based on the assumption of simple
scalability which is an ordinal formulation of the principle of independence
from irrelevant alternatives. This assumption, however, is shown to be inadequate
on both theoretical and experimental grounds. To resolve this
problem, a more general theory of choice based on a covert elimination process
is developed. In this theory, each alternative is viewed as a set of aspects. At
each stage in the process, an aspect is selected (with probability proportional
to its weight), and all the alternatives that do not include the selected aspect
are eliminated. The process continues until all alternatives but one are
eliminated. It is shown (a) that this model is expressible purely in terms of the
choice alternatives without any reference to specific aspects, (i) that it can be
tested using observable choice probabilities, and (c) that it generalizes the
choice models of R. D. Luce and of F. Restle. Empirical support from a study
of psychophysical and preferential judgments is presented. The strategic implications
of the present development are sketched, and the logic of elimination
by aspects is discussed from both psychological and decision-theoretical
viewpoints.