principles that guide the scientific enterprise. They include seeking conceptual (theoretical) understanding, posing empirically testable and refutable hypotheses, designing studies that test and can rule out competing counterhypotheses, using observational methods linked to theory that enable other scientists to verify their accuracy, and recognizing the importance of both independent replication and generalization. It is very unlikely that any one study would possess all of these qualities. Nevertheless, what unites scientific inquiry is the primacy of empirical test of conjectures and formal hypotheses using well-codified observation methods and rigorous designs, and subjecting findings to peer review. It is, in John Dewey’s expression, “competent inquiry” that produces what philosophers call “knowledge claims” that are justified or “warranted” by pertinent, empirical evidence (or in mathematics, deductive proof). Scientific reasoning takes place amid (often quantifiable) uncertainty (Schum, 1994); its assertions are subject to challenge, replication, and revision as knowledge is refined over time. The long-term goal of much of science is to produce theory that can offer a stable encapsulation of “facts” that generalizes beyond the particular. In this chapter, then, we spell out what we see as the commonalities among all scientific endeavors.

As our work began, we attempted to distinguish scientific investigations in education from those in the social, physical, and life sciences by exploring the philosophy of science and social science; the conduct of physical, life, and social science investigations; and the conduct of scientific research on education. We also asked a panel of senior government officials who fund and manage research in education and the social and behavioral sciences, and a panel of distinguished scholars from psychometrics, linguistic anthropology, labor economics and law, to distinguish principles of evidence across fields (see National Research Council, 2001d). Ultimately, we failed to convince ourselves that at a fundamental level beyond the differences in specialized techniques and objects of inquiry across the individual sciences, a meaningful distinction could be made among social, physical, and life science research and scientific research in education. At times we thought we had an example that would demonstrate the distinction, only to find our hypothesis refuted by evidence that the distinction was not real.

Thus, the committee concluded that the set of guiding principles that apply to scientific inquiry in education are the same set of principles that