Bruce Glymour Data and Phenomena: a Distinction Reconsidered

Bogen and Woodward (1988) advance a distinction between data and phenomena. Roughly, the former are the observations reported by experimental scientists, the latter are objective, stable features of the world to which scientists infer based on patterns in reliable data. While phenomena are explained by theories, data are not, and so the empirical basis for an inference to a theory consists in claims about phenomena. McAllister (1997) has recently offered a critique of their version of this distinction, offering in its place a version on which phenomena are theory laden, and hence on which the empirical support for inferences to theories is also, unavoidably, theory laden. In this commentary I argue that McAllister and Bogen and Woodward are mistaken in thinking that the distinction is necessary, and that the empirical support for inferences to theories is not necessarily theory laden in the way McAllister’s account entails they are. Bogen and Woodward in their (1988) are concerned to address three problems about the nature of scientific evidence. (1) Observations are taken to provide reason to accept theories because they provide evidence for those theories. But theories do not in general explain any particular observational datum. How then can any particular datum or set of such be evidence for a theory, and if observations cannot be evidence for theories, how can they provide reason for accepting a theory? Say that a datum or set of data count as reason to accept or reject some theory provided it bears some particular relation to the theory, and call that relation the evidential relation. What, Bogen and Woodward ask, is the evidential relation? (2) While some data are counted as evidence for or against theories, other data are not even potential candidates for evidential status. Although these data appear to bear the same logical relationship to relevant theories as do other data, they are simply ignored as artifacts of the experimental design, as so much experimental noise. What property or properties of a datum or a data set, then, make it a candidate for evidential status, or, as I shall say, what are the qualifying properties a datum or data set must exhibit if it is to be a candidate for evidential status? (3) Are the evidential relation and the qualifying properties such that scientific evidence must necessarily be theory laden, i.e. be infected by the theories employed by the scientists collecting data, or inferring from data to theories? Erkenntnis 52: 29–37, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands.