BACKGROUND: Scientific research on controversial subjects, such as spirituality-and-health, raises several issues about scientific activity that should be properly clarified for an adequate conduction of the investigations. OBJECTIVES: To highlight some topics of philosophy of science that can be useful in the exploration of unknown, or poorly known, aspects of reality. METHODS: By reviewing briefly the concepts of paradigm, normal science and scientific revolution, introduced by Thomas Kuhn, we discuss a set of criteria for evaluating scientific hypotheses, and present some general epistemological guidelines for the scientific exploration of new fields. RESULTS: Scientific activity should be based on theories exhibiting empirical adequacy, falseability, predictive accuracy, broadness of scope, simplicity, theoretical integration, theoretical ordering, and capacity to predict new kinds of phenomena. The proposed guidelines are: to take experimental findings seriously, even when they do not fit into the current paradigm; to search for a theory capable of guiding investigation; to avoid both the dogmatic rejection and the hasty acceptance of new hypotheses; and, in theory evaluation, to take care in not attributing undue value to the context in which the theory was first conceived, or to the authority of the persons who profess or reject it. CONCLUSION: The scientific exploration of new areas is rendered more fruitful by a thorough understanding of the nature of scientific activity, specially of what Kuhn has called "extraordinary science" (in contrast with "normal science").
Epistemology; Thomas Kuhn; spirituality; psychiatry; scientific method