Theory and Observation in the Philosophy of Science

Dale Jacquette, The Pennsylvania State University

1. A Fundamental Distinction

The distinction between theory and observation was once a mainstay in phi- losophy of science, but has since fallen under suspicion as too simplistic. The idea of distinguishing between theoretical and observation terms in scientific practice is obvious enough. It also has an illustrious pedigree, extending back at least as far as Hippocrates’s sage diagnostic advice to Greek physicians, when he maintains: In Medicine one must pay attention not to plausible theorizing but to experience and reason together … I agree that theorizing is to be approved, provided that it is based on facts, and systematically makes its deductions from what is observed … But conclusions drawn by the unaided reason can hardly be serviceable; only those drawn from observed facts. 1 We cannot do science without collecting data, which we accomplish by observ- ing the natural world. We gather information about different types of phenom- ena, and then systematize the information and eventually formulate theories to explain and predict events. To delineate the origins of science in this way is to rehearse in broad outline the concept of scientific method that Francis Bacon describes in Novum Organon, a textbook characterization of what has come to seem a naive model of how science works. There is nevertheless something almost irresistible about this way of thinking about the construction of scientific theories. Of course, there must be data, but not data alone. And, of course, there must be hypotheses to explain and pre- dict phenomena based on empirical data, rigorously tested by experiment and efforts at falsification, and all that we have come to expect of sound scientific reasoning. Furthermore, in some sense, the data harvested through observa- tion must come before the theory offered to explain the data. Chronologically, perhaps, or in terms of epistemic justification or methodological priority as scientific practice is best explained in metascientific accounts of scientific prin- ciples, there is a temptation to agree with Bacon that we must first observe and then try theoretically to explain and predict nature.

1 Hippocrates, Precepts, quoted by Chester W. Starr, in A History of the Modern World, third edition (New York: Oxford University Press, 1983), p. 331. 178 Dale Jacquette

We should try to appreciate the main attractions of the Baconian model for whatever they are worth, without either assuming in advance that the model must be faulty or falling victim uncritically to its charm. We should also try to understand why not only Bacon but many later philosophers of science have been drawn to this way of thinking about the conduct of scientific inquiry in terms of some form of the distinction between theory and observation. This much is clear without simply accepting or rejecting the Baconian model – if in any sense observation comes before theory, then in that sense and to that degree it must also be meaningful to distinguish between theory and observation.

2. Logical, Epistemic and Anthropological Rationale

There are three categories of intuitive considerations in support of Bacon’s distinction, which can be described as logical, epistemic, and anthropological. If we cannot spin theory out of whole cloth, then we are going to need at least some observations on which a scientific theory can be grounded, a fund of data about which to theorize and in terms of which theories can be checked, criticized, and confirmed to some relative degree of probability or overturned in the course of ongoing scientific study. Logical grounds for distinguishing between theory and observation involve the fact that theory logically depends on observation. Theory requires observa- tional data from and on the basis of which a theory can be built, about which a theory theorizes, and without which there is nothing for a theory to predict or explain. The epistemic rationale calls attention to the need for observations in justifying a theory’s truth, for checking, testing, confirming or disconfirming a system of propositions in order for it in the usual sense to qualify as a scien- tific theory. Anthropological grounds for the theory-observation distinction, in Bacon’s and other accounts in the philosophy of science, dovetailing with and usually well-integrated with the first two, is that from a historical perspective as we consider the development of science as a cultural phenomenon, it seems undeniable to suppose that observations were made long before anything rec- ognizable as theoretical science even in its most rudimentary form emerged as a social practice. We begin with observations, and only later propose scientific theories. With- out observations, we would have nothing to explain or predict, and no way to judge the success or failure of efforts at scientific theorization. If we consider the evolution of scientific practice, it appears almost undeniable that our ances- tors before the dawn of science, before anything resembling a scientific theory had ever been formulated even in the most animistic, totemic or mythological religious terms, undoubtedly made observations of the world. Observation, it is tempting to say in Aristotelian terms, is passive, available even to extralinguistic cognitive subjects in the nonhuman animal kingdom,