When first published twenty years ago, The Logic of Medicine presented a new way of thinking about clinical medicine as a scholarly discipline as well as a profession. Since then, advances in research and technology have revolutionized both the practice and theory of medicine. In this new, extensively rewritten edition, Dr. Murphy includes changes to show how these different areas of scholarship may affect details of "the logic of medicine" without compromising its fundamental coherence. New to this edition are discussions (...) of the challenge of the flood of new empirical data, new ideas in genetics, molecular biology, homeostasis, pathogenesis, cancer, aging, and Alzheimer's disease. Murphy also comments on such new theoretical topics as dynamic systems, chaos, and fractals and their impact on the burgeoning fields of philosophy and practice of medicine. Written with medical students in mind, the book includes a glossary, many new examples, and problems for solutions with comments on each. An entirely new chapter deals with modeling. Clinicians and researchers will also find the principles thought-provoking and illuminating. (shrink)

This book reflects upon the manner in which medical research is performed and interpreted.

The formal properties of orbits in a plane are explored by elementary topology. The notions developed from first principles include: convex and polygonal orbits; convexity; orientation, winding number and interior; convex and star-shaped regions. It is shown that an orbit that is convex with respect to each of its interior points bounds a convex region. Also, an orbit that is convex with respect to a fixed point bounds a star-shaped region.Biological considerations that directed interest to these patterns are indicated, and (...) the implications of the prospect of higher orders of star-shapedness mentioned. (shrink)

Some properties are discussed of regular polygons that may result from angular homeostatic processes in stable orbit. To characterize these homeostatic polygons we need to discuss the winding number, the sidedness (integer, fractional and irrational), multiplicity, envelopes, and density. A regular (i.e., equilateral, equiangular) polygon may be closed in one revolution about its unique center, in multiple revolutions, or not at all. A homeostatic polygon can be generated only if all vertices are included in a single polygon, which occurs if (...) and only if the number of vertices and the number of revolutions required to complete the polygon are relatively prime. For the homeostatic polygon to have a finite number of sides (without repeating itself) the angle subtended by any two successive vertices at the center must be a rational multiple of 2. Biological implications of these properties are illustrated. (shrink)

From the standpoint of the theory of medicine, a formulation is given of three types of reasoning used by physicians. The first is deduction from probability models (as in prognosis or genetic counseling for Mendelian disorders). It is a branch of mathematics that leads to predictive statements about outcomes of individual events in terms of known formal assumptions and parameters. The second type is inference (as in interpreting clinical trials). In it the arguments from replications of the same process (data) (...) lead to conclusions about the parameters of a system, without calling into question either the probabilistic model or the criteria of evidence. The third is illation (as in the elucidation of symptoms in a patient). It is a process whereby, in the light of the total evidence and the conclusions from the other types of reasoning, one may modify, expand, simplify or demolish a conceptual framework proposed for deductions, and modify the nature of the evidence sought, the criteriology, the axioms, and the surmised complexity of the scientific theory. (The process of diagnosis as applied to a patient may in extreme cases lead to the discovery of an entirely new disease with its own, quite new, set of diagnostic criteria. This course cannot be accommodated inside either of the other two types of reasoning.) Illation has something of the character of Kuhn's scientific revolution in physics; but it differs in that it is the nature, not the degree or frequency of change that distinguishes it from Kuhn's normal science. (shrink)

The skewness of a distribution, a poorly-defined term, is conventionally deemed to be invariant under linear transformations. A comparison is made of three criteria of it: the sign of odd central moments; the several relationships of the mean, the median and the mode; and asymmetry proper which is the set of ratios of the probability densities of all pairs of points equidistant above and below some arbitrary point, usually the principal mode. Some useful general relationships are discussed. The skeness of (...) convolutions is briefly discussed. A class of distributions is identified for which the skewness of the minimum ofk competing processes is independent ofk. It has importance in the parametric study of survivorship. (shrink)

SummaryCertain revolutionary changes in medicine—measurement, chemistry, genetics—have led to recasting both the criteriology and the conceptualization of the terms of discourse. But advances along this path rest no longer on naive observation but intimately and inextricably involve modeling, that is, a system of inference which derives no immediate warrant from the primordial data of the senses. This system is not totally new in quality, since all “fact” involves interpretation of data; nor is it entirely new in having heuristic value in (...) unearthing, or calling attention to, unsuspected evidence. But it differs in two major respects. First, it requires patterns of surmise which can no longer be immediately corroborated at all stages by naive means but rest more and more on internal theoretical consistency and confirmatory predictions to be verified by other sophisticated and indirect means. Second, it is leading to fundamental upheavals in even the broad perception of human biology, undermining well-established groupings and exposing certain classical fields of inquiry as meaningless. The problem yet to be confronted in this field is how an epistemology of the model (in this sense) is to be constructed. The model is useless (as the whole scientific endeavor is useless) if it has not a more economical structure than the totality of the raw data, even if the success of this economy is in some degree factitious (“robustness”). On the other hand, the model is also useless unless it has heuristic value and helps in adjudicating among competing interpretations (“power”). A good model will help also to distinguish relevant aspects of the data from the irrelevancies ascribed to error. The paradigmatic function of the model, then, defines certain “sufficient statistics” which condense the relevant features of the data. In fact a close analogy can be developed between the methodology of statistical inference and nosology. Both are necessarily tentative, and healthy development of both, in practice, is iterative; that is, the evidence and the model are mutually correcting and lead to advancement one of another. (shrink)

The epistemology and ontology of experimentation are discussed in depth with special reference to biology and medicine. Two types of experiments are distinguished: exploratory (or "blazing") and consolidating. They Have objectives and canons that are strikingly different. A contrast is drawn between the literalism of the most pragmatic scientists and the formalism of most statisticians. The terms and notions of the one may have imperfect correspondence with those of the other, or perhaps none at all. The dangers are pointed out (...) of both the conclusion that the gap between the two is unbridgeable and the contrary view that the gap is trivial and merits no serious attention. Substantive discussions address the choice and meaning of a metric, the idea of interaction and time series analysis, the ontology of variation, and the epistemology of randomization, hypothesis-seeking, and multiple comparisons. * From the Division of Medical Genetics, Johns Hopkins University School of Medicine, Baltimore Md. 21205. The research in this paper was supported by grants number GM24736 and RR007722 of the National Institutes of Health. Text of a lecture given to the Maryland Institute for Clinical Research and the Department of Social and Preventive Medicine, University of Maryland, October 6, 1980. CiteULike Connotea Del.icio.us What's this? (shrink)

In this paper I shall try to analyse appropriate logic and actual methods as a preliminary to developing expert systems that will simulate clinical diagnosis. It is doubtful that all diagnoses address the same kind of problem and hence no one logic will suffice. Sometimes the signs and symptoms manifest an underlying disorder that cannot be observed directly (the substantialist model); sometimes there seems to be no underlying disorder and the diagnosis is a rearrangement of the data (the nominalist model). (...) In deciding their merits in the particular case, we must identify the sources of variation; what is meant by saying that the data are independent; and what can be meant by wrong diagnosis and misclassification. Problems arise in human diagnosis because the data may be false, even lies; because the known list of diseases is not exhaustive; and because the probability of multiple unrelated diseases increases with age. Special difficulties arise from homeostasis (which is fundamental in defining and understanding disease) because the primary disturbances may be hard to distinguish from the homeostatic responses to them. (shrink)

In this paper are explored the ethical implications of the answers to three questions: Whether or not a diseased state is discrete; the criteria by which that question is answered; and how the diseased state is to be identified. Examples are given showing that some states appear to be clearly discrete, and others equally clearly not discrete. The nature of the pertinent evidence will be affected accordingly. It is shown that a slavish and inappropriate concern with categories leads to anomalous (...) ethics. Finally, it is suggested that many of these problems may be avoided by centering the ethics of medicine on optimizing the welfare of the patient rather than by thinking in terms of categorical disease. (shrink)

Thus far in the development of the discipline of medical ethics, the overriding concern has been with solutions to specific problems. But discussion is hampered by lack of understanding of the scope and methodology of medical ethics, and its scientific and philosophical basis. In Underpinnings of Medical Ethics Edmond A. Murphy, James J. Butzow, and Edward L. Suarez-Murias offer much-needed clarification of the purview, ontological basis, and methodology of a medical ethics that is to be comprehensive and yet readily accepted (...) by all. The authors begin by describing the scope of the analysis and discussing possible ethical systems and paradigms. They then deal with the structures and concepts necessary in the formulation of a coherent philosophy: normality and disease, scientific and juridical law, certainty and certitude, decisions. Finally, they introduce particular human dimensions, such as quality of life, pain, and responsibility. Throughout, case examples illustrate the authors' theoretical framework. (shrink)