Carl Gustav Hempel Research Paper

1. Biography

Hempel was born on 8th January, 1905, in Oranienburg (near Berlin, Germany). He studied mathematics, physics, and philosophy at the universities of Gottingen, Heidelberg, and Berlin from 1923 to 1929. After graduation (‘Staatsexamen’) that qualified him to teach in secondary schools (‘Gymnasien’) Hempel went to Vienna to study with Moritz Schlick and, particularly, Rudolf Carnap. Both of them, together with the mathematician Hans Hahn and the economist Otto Neurath and others, had founded in 1923 the ‘Vienna Circle’ (‘Wiener Kreis’), that was to become the nucleus of logical empiricism. After his return to Berlin in 1930 Hempel entered teacher’s training and teaching and worked at the same time with Hans Reichenbach, head of the ‘Berlin Group’ of logical empiricism, on a philosophical dissertation on the concept of probability. After graduation in 1934 Hempel preferred to leave Nazi Germany and went to Brussels to assist Paul Oppenheim, a private scholar, in carrying out philosophical research that related principally to concept formation in empirical science. In 1937 to 1938 Hempel worked for a year as research associate with Carnap in Chicago, and again went back to Brussels until he found a post of instructor at City College, New York in 1939. The academic year 1940 to 1941 saw him at Queens College, New York, from where he went as associate professor to Yale in 1948. In 1955 Hempel became Stuart Professor of Philosophy at Princeton. After retirement at Princeton (1973) he worked as university professor at Pittsburgh University from 1977 until 1985. He died at Princeton on 9 November, 1997.

2. Major Contributions

Hempel has given important contributions: (a) to the rational reconstruction of methodological concepts, particularly the concept of scientific explanation; (b) to the ‘universality thesis,’ i.e., the thesis that the social sciences do not, and should not, use methods that are essentially different from the methods of empirical science; and (c) to concept formation and taxonomy in empirical science.

2.1 Scientific Explanation

Hempel reconstructs scientific explanations of concrete events in nature, history, and society as arguments, i.e. as logical deductions containing as premises (‘explanans’) at least one (general) scientific law LI, as well as initial and boundary conditions Cr, and as conclusion (‘explanandum’) the statement E describing the event in question. We thus obtain the following model of ‘deductive-nomological (D-N) explanation’

In case the explanandum contains essentially a statistical law (e.g., for all x: the probability of G, if F is given, equals r and as boundary condition that F is given for some b) the explanatory argument does not deliver a deduction of the explanandum statement E but rather gives inductive support for E, i.e., the explanans shows that E was to be expected with a certain degree r of probability. In simplified form (one statistical law, one boundary condition) we thus obtain the following model of ‘inductive-statistical (I-S) explanation’:

In the case of I-S explanation, one must further assume that the explanans is maximally specified, i.e., the explanans must contain all available information that is possibly relevant for the explanation of the explanandum E. Or, in other words, the explanandum must contain all pertinent statistical laws and those special facts that can be connected with the E-event by statistical laws. I-S explanations thus relate to the body of scientific knowledge at a given time, i.e., they become ‘epistemically relative.’ The postulate of maximum specificity avoids the ‘explanatory ambiguity,’ i.e., the possibility to give acceptable I-S explanations based on true premises for mutually exclusive explananda.

In case one deduces as explanandum a general or a statistical law of lesser generality than the one(s) in the explanandum one obtains the reduction of a law or theory in the first case (e.g., explaining the law of free fall by means of the law of gravitation), and a deductive-statistical or D-S explanation of a statistical law by a more comprehensive statistical law in the second.

Originally Hempel claimed the structural identity of explanation and prediction. Later he had to admit that, although every adequate explanation is (under pragmatically changed circumstances) also a prediction, not every adequate prediction yields also an adequate explanation, for symptoms are often adequate for a prediction, but not for the corresponding explanation. So is, for example, a sudden fall of the barometer (together with suitable laws) sufficient for predicting a thunderstorm, but it does not explain it, since the fall of the barometer is not the cause of the thunderstorm, but rather a symptom of its arrival.

2.2 Unity Of Science

Hempel claims the methodological unity of empirical science. With respect to scientific explanation this amounts to a universality thesis of scientific explanation: there is no essential difference between explanations in the natural sciences and those in psychology, the social sciences, or history. Explanations in these fields aim to show that the event in question was to be expected on the basis of antecedent and boundary conditions and general laws. In history those general laws are usually taken from psychology, sociology, economics, the natural sciences, etc. Hempel leaves the question open whether genuine historical laws exist. Normally explanations in history and sociology fail to include an explicit statement of the laws they presuppose. This failure is due to the fact that those laws are part of folk psychology and seem to be tacitly taken for granted. Apart from that it is difficult to formulate in a sufficiently exact way the underlying general assumptions about e.g., the outbreak and course of revolutions. Furthermore, most of the regularities in the social sciences are statistical. Therefore one can only expect explanation sketches in these fields.

The method of empathic understanding that is often claimed to distinguish the social from the natural sciences is neither sufficient, nor necessary for explanations in these fields. It is not sufficient, because the individual act of understanding is only a heuristic device in order to suggest general psychological hypotheses that might subsequently serve as explanatory principles in the case under consideration. It is not necessary, because a historian might well be able to explain the deeds of a paranoiac historic personality by reference to the principles of abnormal psychology without being able to arrive at an empathic understanding of such a personality.

2.3 Concept Formation In Empirical Science

Hempel’s work on concept formation in empirical science originates in his early cooperation with Paul Oppenheim and consists basically in the application of principles of logical empiricism to the formation of scientific concepts. Hempel distinguishes: (a) classificatory; (b) comparative; and (c) quantitative concepts. These distinctions normally characterize at the same time the historical development of a science from its initial descriptive ‘natural history’ stages to its mature theoretical stages. Classification divides a given set or class of objects (e.g., human beings) into subclasses (e.g., beings that suffer from certain mental disorders). Each of these subclasses is defined by means of a certain concept (e.g., schizophrenia) that represents the complex of characteristics essential for the membership in that subclass. Hempel speaks also of ‘classificatory types.’ The elements of these subclasses are those individuals to whom the respective concept applies (e.g., schizophrenics). The characteristics that form the defining concept are ascertainable fairly directly by observation. Classificatory concepts as well as scientific concepts in general have to fulfil two requirements. They have: (a) to be objective; and (b) to have systematic import. Objectivity is attained first by using operational criteria and (often only partial) operational definitions in a large sense that includes observation as operational and second by eliminating criteria with valuation overtones. Scientific concepts have systematic import if they lend themselves to the formulation of general laws or theoretical principles. Whereas classificatory concepts are a yes-or-no affair, i.e., a certain individual belongs to some subclass or it does not, comparative concepts admit of more or less with respect to a certain trait (e.g., x is warmer than y with respect to cold–hot). They lead to (quasi)linear orderings as soon as one includes the relation of coincidence (e.g., x is equally warm as y). Hempel calls the extremes of such orderings ‘ordering types.’ The next step would consist in giving these linear orderings a metric and thus arriving at quantitative concepts (e.g., temperature).

For Hempel the ‘ideal types’ that have become popular in the social sciences since Max Weber are neither classificatory nor ordering types. Ideal types are interpretative or explanatory schemas that contain a set of empirical generalizations that establish subjectively meaningful connections between different aspects of some kind of phenomenon, e.g., purely rational economic behavior, a capitalist society, a religious sect. Accordingly ideal types must rather be reconstructed not as concepts but as theoretical systems that are intended to provide explanations and therefore must contain testable hypotheses. Despite their lack of clarity and precision there thus are also with respect to ideal types no essential methodological differences between psychology or the social sciences and the corresponding methods in the natural sciences.

3. Influence, Impact, And Current Significance

Hempel’s ideas constitute the mature form of logic empiricist thinking. His work on scientific explanation ‘stands out as the benchmark to which all subsequent studies of this topic must be referred’ (Salmon 1998, p. vii). His reconstruction of concept formation in empirical science has become a sort of standard for objective procedures of concept formation. It has greatly influenced subsequent editions of the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association (Houts 2001). His later work reflects the openness of logical empiricism to new developments in the philosophy of science (particularly T. S. Kuhn’s work) that put a strong emphasis on the historical and sociological (‘pragmatic’) factors of the development of science (Wolters 2000).

Bibliography:

1. Hempel C G, Oppenheim P 1936 Der Typusbegriff im Lichte der Neuen Logik. Wissenschaftstheoretische Untersuchungen zur Konstitutionsforschung und Psychologie. A. W. Sijthoff, Leiden, The Netherlands
2. Hempel C G 1952 Fundamentals of concept formation in empirical science. International Encyclopedia of Unified Science. University of Chicago Press, Chicago, Vol. II, no. 7
3. Hempel C G 1965 Aspects of Scientific Explanation and Other Essays in the Philosophy of Science. The Free Press, New York Hempel C G 1967 Philosophy of Natural Science. Prentice-Hall,
4. Englewood Cliffs, NJ
5. Hempel C G 1979 Scientific rationality: Analytic vs. pragmatic perspectives. In: Geraets T F (ed.) Rationality To-Day—La Rationalite Aujourd’hui. University of Ottawa Press, Ottawa, ON, pp. 46–66
6. Hempel C G 2000 Selected Philosophical Essays. Jeffrey R (ed.). Cambridge University Press, Cambridge, UK
7. Houts A C 2001 The diagnostic and statistical manual’s new white coat and circularity of plausible dysfunctions: Response to Wakefield. Behaviour Research and Therapy 38: 315–45
8. Salmon W C 1989 Four Decades of Scientific Explanation. University of Minnesota Press, Minneapolis, MN
9. Salmon W C 1998 Causality and Explanation. Oxford University Press, Oxford, UK
10. Wolters G 2000 Die pragmatische Vollendung des logischen Empirismus—In memoriam Carl Gustav Hempel (1905– 1997). Zeitschrift fur allgemeine Wissenschaftstheorie 31: 205–42