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").

O objetivo deste artigo é apresentar e discutir as famosas relações de Heisenberg, usualmente denominadas de "princípio da incerteza". A abordagem adotada é primordialmente conceitual, embora referências históricas sejam feitas para auxiliar a exposição. Distinguem-se três interpretações principais das relações, cada uma derivando de bases inteiramente distintas e conduzindo a conseqüências físicas e filosóficas igualmente diferentes.

resumoNeste artigo examina-se a afirmação de Larry Laudan de que "desde a Antigüidade os críticos do realismo epistêmico basearam seu ceticismo numa convicção profundamente enraizada de que a falácia da afirmação do conseqüente é de fato falaciosa". Tal afirmação é confrontada com o "argumento do milagre", formulado por Hilary Putnam, que desempenha papel central na defesa do realismo científico. Embora esse argumento apresente uma estrutura lógica semelhante à da referida falácia, procura-se mostrar que nas circunstâncias especiais em que é empregado captura uma intuição epistemológica legítima e relevante para a ciência. Avalia-se, ao longo da análise, uma série de interpretações e críticas ao argumento por parte de anti-realistas, indicando-se sob que aspectos elas são insatisfatórias, ou podem ser rebatidas.Palavras-chave • Realismo científico. Abdução. Argumento do milagre. Indução pessimista. Método hipotético-dedutivo. Empirismo. Larry Laudan. Hilary Putnam. Arthur Fine.

This article seeks to clarify certain key theoretical, conceptual and philosophical issues in the foundations of microphysics which, to judge from certain recent publications, continue to cause misunderstandings. In particular, we examine the Heisenberg indeterminacy relations, underlining that they are not univocally interpretable and that, at least in the interpretation following directly from the quantum formalism, they are not the target of Einstein, Podolsky and Rosen's criticism. We try to identify the essential goal and premises of this famous argument, with the help of a simple example. Finally, we examine briefly the Bell inequalities, emphasizing that, given their generality, the net consequence of their experimental violation cannot be circumvented neither by the abandonment of determinism nor by any local realistic reinterpretation of measurement results, as attempted in an article recently published in this journal.

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The aim of this article is to offer a rejoinder to an argument against scientific realism put forward by van Fraassen, based on theoretical considerations regarding microphysics. At a certain stage of his general attack to scientific realism, van Fraassen argues, in contrast to what realists typically hold, that empirical regularities should sometimes be regarded as "brute facts", which do not ask for explanation in terms of deeper, unobservable mechanisms. The argument from microphysics formulated by van Fraassen is based on the claim that in microphysics the demand for explanation leads to a demand for the so-called hidden-variable theories, which "runs contrary to at least one major school of thought in twentieth-century physics". It is shown here that this argument does not represent an insurmountable obstacle to scientific realism, not even when a series of important theoretical and experimental results against hidden-variable theories-and not merely a conflict with a certain school of thought-is taken into account. The scientific attitude is that correlations cry out for explanation.

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