Hans reichenbach philosophy skin

The laws of mechanics specify or define an order of events—event A causes B which in turn causes C, and so on—but not a temporal direction, so, from the laws of temporal ordering, it would be perfectly possible for that order to be reversed, or for time to "run backwards," so to speak. But the actual direction of time is discovered through irreversible processes of nature, so, again, theoretical developments yield to empirical determinations.

In philosophy of science , Reichenbach distinguished between the "context of discovery" and the "context of justification. He also distinguished between conventionalism and empiricism , and opted for empiricism as the correct approach to science. In his work on quantum theory, Reichenbach pointed out that there is no interpretation of quantum mechanics that does not have causal anomalies, meaning that the principle of local action is refuted and action seems to take place over a distance.

The only two theories that do not have this problem are the Bohr-Heisenberg formulation, based on the principle of indeterminacy, in which there is no way to measure both the position and the momentum of elementary particles. Heisenberg thought that this interpretation was faulty. The other possibility is the adoption of a three-valued logic, instead of the usual two-valued, true or false one; that three-valued logic would have three truth values: True, false, and indeterminate.

He also worked out a mathematical formulation and axiomatization of quantum mechanics. In , the year he moved to the United States and became a professor at the University of California at Los Angeles, Reichenbach's Experience and Prediction was published. His work on quantum mechanics, Philosophic Foundations of Quantum Mechanics, was published in He then wrote two popular books: Elements of Symbolic Logic and The Rise of Scientific Philosophy —the latter of those strongly attacked and attempted to discredit pre-scientific philosophy.

When Reichenbach died he was working on the philosophy of time, and two books that were products of that study, Nomological Statements and Admissible Operations and The Direction of Time were published posthumously. New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards.

Popper, K. Bunge, ed. Putnam, H. Baumrin, ed. Reichenbach, H. Ostwald, ed. English translation to be published in R. Cohen et al. Versuch einer Synthese der freistudentischen Ideen. English translation: H. Reichenbach English translation, Reichenbach Book Google Scholar. Reprinted in H. English Translation of Reichenbach English translation of Reichenbach Translation of Reichenbach Reprint of Reichenbach Rescher, N.

Russell, B. Reprinted, , Dover Publications, New York. Norton and Co. Salmon, W. Feyerabend et al. Chapter Google Scholar.

Hans reichenbach philosophy skin

Nakhnikian, ed. Butts et al. Savage, L. Schlick, M. Schuster, C. Gillispie, ed. Stein, H. Stevenson, C. Strauss, M. Strawson, P. Suppes, P. Reprinted in Hooker Venn, J. Wheeler, J. Whitehead, A. Winnie, J. Download references. You can also search for this author in PubMed Google Scholar. Reprints and permissions. The Philosophy of Hans Reichenbach.

In: Salmon, W. Synthese Library, vol Springer, Dordrecht. When Adolf Hitler became Chancellor of Germany in , Reichenbach was immediately dismissed from his appointment at the University of Berlin under the government's so called "Race Laws" due to his Jewish ancestry. Reichenbach himself did not practise Judaism, and his mother was a German Protestant, but he nevertheless suffered problems.

He thereupon emigrated to Turkey , where he headed the department of philosophy at Istanbul University. He introduced interdisciplinary seminars and courses on scientific subjects, and in he published The Theory of Probability. In , with the help of Charles W. During his time there, he published several of his most notable books, including Philosophic Foundations of Quantum Mechanics in , Elements of Symbolic Logic in , and The Rise of Scientific Philosophy his most popular book in Reichenbach died unexpectedly of a heart attack on April 9, He was living in Los Angeles at the time, and had been working on problems in the philosophy of time and on the nature of scientific laws.

As part of this he proposed a three part model of time in language, involving speech time, event time and — critically — reference time, which has been used by linguists since for describing tenses. Hans Reichenbach manuscripts, photographs, lectures, correspondence, drawings and other related materials are maintained by the Archives of Scientific Philosophy, Special Collections, University Library System, University of Pittsburgh.

Some more notable content includes:. Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version. In other projects. Wikimedia Commons Wikiquote Wikisource Wikidata item. German philosopher — Hamburg , German Empire. Los Angeles , California , U. Early life [ edit ]. Political activism [ edit ].

Academic career [ edit ]. In combination with the representation of probability relations by claims in a quasilogical language, the limiting frequency interpretation creates fundamental formal problems that Reichenbach did not foresee. Sets of limiting relative frequencies are not closed under finite intersection; they are not closed under countable union; they do not satisfy countable additivity.

They do not, in other words, form a sigma field, or a Borel field, or even a field. See the entries on interpretations of probability , the early development of set theory , and set theory. These and several other mathematical difficulties of Reichenbach's setup are described in van Fraassen Reichenbach imposes two further axioms—the axioms of order f, p.

The second, however, appears to be a very strong stationarity principle that is not generally true: the probability of one variable conditional on a specified common lag of other variables is invariant under all uniform translations of the lags. This axiom seems to derive directly from Reichenbach's interpretation of the foundations of probability, in particular from Reichenbach's assumption about normal sequences, described below.

In addition to an axiomatization, Reichenbach attempts to provide a foundation for probability claims in terms of properties of sequences, similar to von Mises. Reichenbach's definition of lack of aftereffect is not based on initial segments of sequences, but rather on subsequences selected by a particular set of rules f, p. We are unable to reconstruct exactly what Reichenbach may have intended, in particular since his definition of lack of aftereffect is difficult to distinguish from the criterion of invariance under subsequence selection.

If our reconstruction is correct, this would distinguish Reichenbach's account of lack of aftereffect from that of invariance under subsequence selection, because the former includes subsequence selection rules that depend on the values of certain items in the sequence, while the latter includes only rules that are based on the indices. Two more definitions are required for the full picture.

Second, a subsequence selected by an algebraic rule that partitions the sequence A —e. This condition of regular divisions seems to underlie the stationarity expressed in the second axiom of order. If random sequences are taken to satisfy at least the conditions of the lack of aftereffect and invariance of subsequence selection under any selection rule, then Reichenbach's restriction of subsequence selection rules to regular divisions implies that the set of normal sequences is a proper superset of that of random sequences.

Reichenbach accepts this weakening to avoid some of the difficulties in characterizing a random sequence, and to broaden his earlier notions of probability to include sequences of trials, which might not be perfectly independent. In later writings, he seems to suggest that as long as the sequence converges, probability claims can be applied to the component events.

A large section of the book is devoted to reconstructing classical results in the theory of probability as claims about relative frequencies, including various continuous distributions and Bernoulli's theorem. The remainder of the book is not about probability per se, but about its epistemological role. Reichenbach began his philosophical career as a neo-Kantian, a perspective that is evident in his thesis and in his first book-length effort f after his doctoral thesis, and that at least echoes in his later work.

The aim of The Theory of Relativity and A Priori Knowledge is to reconcile Kantian theory in a limited way with the theory of relativity by distinguishing two senses of synthetic a priori: Principles governing the content of experience can be synthetic a priori because they are necessary, transcendental truths, or because they are non-empirical principles that form part of how we construct our representation of reality, and are thus revisable.

What that something is, Reichenbach never clearly describes. While a priori in the constitutive sense, the coordination principles are contingent, they could be changed if experience makes others more convenient. The picture is very much like that C. Lewis offers at about the same time in Mind and the World Order He did not view his contemporaries uniformly.

For Moritz Schlick, Reichenbach seems to have had a somewhat condescending respect, for Ludwig Wittgenstein, who is one of the few philosophers whom he later criticizes by name in Experience and Prediction c , and for Karl Popper, none whatsoever. Aside from Einstein, his deepest respect and closest intellectual alliances seem to have been with Kurt Lewin, Kurt Grelling, Rudolf Carnap, Richard von Mises although they do not seem to have got along personally and Bertrand Russell, although Reichenbach was not pleased with Russell's criticism of his views in Russell's last philosophical book, Human Knowledge, Its Scope and Limits Russell, ; see Reichenbach , vol.

Chapter 2 of Ryckman provides a very clear attempt at reconstructing Reichenbach's struggle with Kantian principles in the s. Chapter 6 of Milmed traces the Kantian elements in Reichenbach's epistemology and discusses the conflicts that arise, though the analysis concerns primarily Reichenbach's mature views. By the s Reichenbach abandoned foundationalism altogether and adopted an epistemological position closer to pragmatism than to logical positivism.

Reichenbach's mature viewpoint, presented in Experience and Prediction c diminishes the status of the given; knowledge, belief and conjecture is built around his conceptions of meaning, probability and convention. Coordination of language and physical circumstances replaces his earlier coordination of Kantian concepts and sensation. Reichenbach is a realist about the external world, but asserts that we can only have uncertain knowledge about it, inferred from sense data.

Deliberation can reject the gifts of perception so involuntarily received. Claims about ordinary objects, and scientific claims about other kinds of objects, whether sense data or atoms, are probabilistic in nature and related by probabilities, not by any kind of logical reduction. Reichenbach was not alone in this view at the time. In , in the second issue of Analysis , Hempel, writing in English because Carnap could not at the time, described Carnap's viewpoint in similar, if not quite identical, antifoundationalist terms.

The overall account seems to be something like the following: Language requires a coordination of words—or at least sentences—with something signified. He gives no account of how such an act can suffice to specify a rule, and he recognizes instances in which it does not, for example that a coordination that measures time by the behavior of clocks does not suffice to provide a rule for deciding relations of time measurements between distant clocks.

Various coordinative definitions may thus leave measures of other quantities or relations indeterminate, and these must be specified by some stipulation or other. His chief, but not only, example is the definition of simultaneity see also Rynasiewicz , and Dieks for a clear discussion. Once specifications of all relevant quantities are made, empirical claims are possible.

There are, in Reichenbach's view, two related ambiguities. Second, the same total theory may be partitioned in more than one way into claims true by stipulation and empirical claims. The equivalence relation he intends is unclear. In earlier writings he suggests that empirically equivalent theories are those that have the same empirically testable consequences; a later formulation is that empirically equivalent theories are those that have the same posterior probability on any observations.

The later characterization is as clear as Reichenbach's characterization of the probability of theories and their confirmation see below. The earlier characterization results in a semantics for which no effective proof theory is possible Glymour, One puzzle about Reichenbach's view of conventions is why characterizing them remained important to him, since they are, in his mature view, only a feature of the reconstruction of a theory, not an intrinsic logical or semantical feature of any proposition.

Reichenbach's emphasis on locating conventions seems instead to be negatively motivated, a continuing prophylactic against claims that various principles are a priori. The immediate description of the perceptual world is in terms of enduring objects, their properties and relationships, and that description is only probable. The argument is not in accord with Reichenbach's own criterion for equivalent descriptions, but the conclusion is repeatedly emphasized.

Reichenbach's mature views on the notion of analytic truth were complex. He no longer held with C. Lewis that there is at any time any sort of Kantian a priori—but there is synonymy, there are equivalent descriptions, and the assertion of equivalence between equivalent descriptions is presumably a purely logical matter, hence analytic. Although explicitly addressed to Carnap, C.

As Quine's senior at Harvard, Lewis was unlikely to be criticized by name. Russell's criticism, and Nelson Goodman's criticism of the very idea of synonymy Goodman, , but perhaps not Quine's, could have been applied to Reichenbach. All empirical claims are, according to Reichenbach, probabilistic judgments based on relative frequencies in a reference class, or reached by induction.

To the extent that reference classes rely on kinds, Reichenbach resorts to psychology: primarily, things are sorted into kinds by the immediate perception of similarity, or by similarity in memory. Less primitively, theory and convention guide the determination of kinds. In practice he recommends the choice of the narrowest reference class for which there are adequate statistics, a recommendation that is of no help why, or why not, should we throw various astrological theories into the reference class for assessing the prior probability of general relativity?

Primary or fundamental inductive inference consists of taking observed relative frequencies as probabilities, that is, as limiting relative frequencies. Reichenbach notes in The Theory of Probability f that without further assumptions nothing can be said about rates of convergence or about the warranted confidence that an empirical distribution has converged.

He further acknowledges that any procedure that estimates the probability to be the relative frequency, plus any quantity that keeps the estimate between 0 and 1 and that itself converges to 0, will also converge to the limiting frequency if such exists. The proposal of the straight rule goes back to the problem of assertability of probability claims he discussed in his thesis.

Reichenbach's proposal is reminiscent of the law of large numbers, that the empirical distribution of a sequence of independent and identically distributed trials converges in probability to the true distribution. But the law of large numbers depends on independent, identically distributed trials. Reichenbach cannot resort to such assumptions if he wants to avoid circularity in his account of inductive inference.

One has no reason to justify this claim, the posit is blind. However, if one had several sequences of measurements resulting in empirical frequency distributions F 1 ,…, F n , then the relative frequencies found in each of these empirical distributions can, according to Reichenbach, be used to get higher order distributional information about the original posit itself, and the posit therefore becomes appraised.

How sure can one be that the appraisal of the posit is accurate? One thus arrives at a hierarchy of posits, of which the lower levels are appraised posits, and the highest levels are blind posits. Just how the integration of different levels is supposed to occur, remains unclear and a point of criticism by Ernest Nagel see below. The approach of estimating higher order distributional information on the basis of subdividing the available sample is similar to the modern statistical procedure of bootstrapping, although there re-sampling techniques are used.

Faster convergence of the first level estimate—the data-level—is somehow supposed to result from simultaneous convergence at all the different levels in this hierarchy of appraised posits—Reichenbach refers to this as the method of cross-induction. But Creary , Ch. Over time and place, the reasons Reichenbach gives for convergence of frequency estimates to a limiting value vary, including 1 his early view that convergence is synthetic a priori, or that 2 the principle of induction expresses a kind of psychological habit, 3 the semantic argument we quoted above in Section 2.

The probability associated with any foundational claim must be understood as a blind posit, i. In a rather mixed metaphor, Reichenbach compares our knowledge of the external world to seeing shadows of flying birds on the walls of a cube in which one is confined. He argues that the patterns on the walls, their regularity, would result in a high probability that there are objects outside the cube producing the shadows.

Reichenbach's eventual anti-foundationalism led him to a contest of opinions with C. Those probabilities can be revised in the light of further experience. Lewis' actual complaint appears to be based on a mathematical error when computing conditional probabilities. A more general problem that appears to have been missed in the discussion at the time is that since Reichenbach held that the probabilities of theories are to be assessed by Bayes rule, his position, unlike Lewis', required a technical account of how claims with non-extremal probabilities can produce changes in the probabilities of others by some generalization of Bayes rule see the entry on Bayes Theorem.

Since on Reichenbach's view uncertainty is associated with observation and perception and scientific theories are only confirmed with a degree of probability, an account is required of how uncertain data changes the probabilities of hypotheses logically remote from the data. Much later, Richard Jeffrey provided an account of Bayesian updating that explicitly relates the probability of the data to the probability of the hypothesis confirmed—or disconfirmed—by the data see the entry on Bayesian epistemology.

Bayes rule and the probabilities of theories posed another problem pressed on Reichenbach by Ernest Nagel in a review in Mind of the German edition of Reichenbach's The Theory of Probability Nagel, ; see also Nagel, In his response to Popper e , Reichenbach had proposed two ways of evaluating theories, one of which is to count the relative frequency of true statements among the consequences of a theory.

Reichenbach does not attempt to defend this proposal in his reply to Nagel in Reichenbach, a. That leaves the assignment of probabilities to theories by Bayes Rule, which Reichenbach had also proposed, but Nagel observes that if theories are to be evaluated by Bayes rule they must have prior probabilities. How can there be a frequentist prior probability for a theory, since we do not know to what reference class to assign a particular theory and, whatever the reference class, according to Reichenbach we do not and cannot know which theories in that class are true?

As in several of his other responses to criticism, Reichenbach's reply is unfortunately more defensive than enlightening. Reichenbach gave a sketch of such a procedure in his reply to Popper, which Nagel pointedly does not think addresses the problems. About the problem of the frequency of true hypotheses in the reference class, Reichenbach says that we only need the probabilities of theories in the reference class, not their truth or falsity—a question-begging reply that Reichenbach must have sensed is unconvincing because he promises to address the issue further in Experience and Prediction c.

The discussion of the prior probabilities of theories in section 43 of Experience and Prediction is unsatisfactory for the same reasons. In his review Reichenbach, e of Popper's The Logic of Scientific Discovery , Reichenbach suggests that theories are ordered by their prior probability, and the theory with the highest prior is further tested.

In Experience and Prediction c and in his reply to Nagel Reichenbach, a , published in the same year, Reichenbach first formulates the distinction between the context of discovery and the context of justification with regard to mathematics: the mathematical relations are what they are, and how we come to recognize them is an entirely different, psychological matter:.

In other words, the distinction is supposed to be between objective relations among premises and conclusions, and subjective ways of discovering those relations. He had one fundamental procedure for estimating true hypotheses: the straight rule, and one secondary procedure, whose application he never coherently explained, Bayes rule with objective, frequentist, prior probabilities for hypotheses.

Putnam provides a helpful big picture of Reichenbach's mature views on metaphysics and epistemology. Chapter 7 of Milmed provides an overview of Reichenbach's probabilistic epistemology and views on induction. Salmon, in various papers see the entry on the problem of induction tried in vain to save the straight rule, Reichenbach's pragmatic vindication of induction see also Hacking, Psillos disentangles Reichenbach's argument for realism.

Galavotti provides a succinct attempt at reconstructing a coherent overall account of Reichenbach's epistemology. Chapter 6 of Milmed provides one of the few good discussions of Reichenbach's views on logic. Almost exclusively, Reichenbach's scientific interest was in physics. He regarded chemistry as an appendage, entirely reducible to physics, and his only publication touching the subject is on Marcelin Bertholot Reichenbach, a , the eminent French anti-vitalist chemist.

He believed Freud's psychoanalytic theories were scientifically warranted by Freud's evidence, and in Los Angeles maintained friendships in the psychoanalytic community, including attending and sometimes lecturing at the Psychoanalytic Institute. As a student Reichenbach showed some interest in psychology Padovani, , p. It seems unlikely that Reichenbach knew Freud's remarkably candid descriptions before of his aggressive data collection procedures, and of course Freud's letters to Wilhelm Fleiss Masson, , which reveal how little Freud thought of his own methodology, were unknown to Reichenbach.

Reichenbach's most original work on the foundations of physics is in three books, Axiomatization of the Theory of Relativity h , Philosophical Foundations of Quantum Mechanics b , and The Direction of Time b. The first attempts an empiricist aufbau of the special and in less detail general theories of relativity from experimentally accessible causal relationships; the second essays a novel 3-valued logic for quantum theory; and the third addresses a long standing problem in physics and metaphysics.

Einstein's lectures on relativity in Berlin in —18, attended at the time by Reichenbach and a handful of others, provided a shock to Reichenbach's viewpoint. The Theory of Relativity and A Priori Knowledge , published in , is an attempt to identify neo-Kantian doctrines that must be abandoned and to articulate what can be salvaged.

Twenty-five years before, in his dissertation published in , Russell had undertaken a similar project in connection with non-Euclidean geometry, arguing that constant curvature is the geometrical synthetic a priori. Most of the book addresses general epistemological issues discussed above rather than issues about physics per se. Between the publication of The Theory of Relativity and A Priori Knowledge , in , and the appearance of The Axiomatization of the Theory of Relativity in , Reichenbach published a series of professional and popular essays expounding or defending the special and general theories and Reichenbach's own axiomatization, which was published in outline in in Physikalische Zeitschrift d.

The professional essays were variously addressed to audiences of philosophers or physicists. They are interesting for our purposes chiefly because they state philosophical positions that Reichenbach had previously rejected, or would later come to reject, or because they offer interpretations of the theories that are problematic.

The Axiomatization is either a work very much out of its time, or the times have not changed much. Reichenbach's statement of purpose might have been written at any time in the last quarter of the 20th century in response to Quine's holism and to Thomas Kuhn's incommensurability thesis see the entries on belief and on Thomas Kuhn. It is not easy to arrive at…a judgment with respect to the axioms of a theory.

Usually the axioms, representing higher levels of abstraction, are quite remote from direct sense perception…. In order to avoid this difficulty…It is possible to start with the observable facts and to end with the abstract conceptualization…The empirical character of the axioms [about observables] is immediately evident and it is easy to see what consequences follow from their respective confirmations or disconfirmations.

Unfortunately…every factual statement, even the simplest one, contains more than an immediate perceptual experience: it is already an interpretation and therefore itself a theory…The most elementary factual statements, therefore, contain some measure of theory…. Does there exist any confirmation other than that of the theory as a whole?

It is nevertheless possible that the new theory, when used for the interpretation of this one fact, makes hardly any difference quantitatively, whereas it leads to considerable changes with respect to other assertions…. The new theory has merely to satisfy the requirement that it will not result in a practically noticeable quantitative difference when applied to these elementary facts…For this reason all axioms of our presentation have been chosen in such a way that they can be derived from the experiments by means of pre-relativistic optics and mechanics.

All are facts that can be tested without the use of the theory of relativity…The particular factual statements of the theory of relativity can all be grasped by means of pre-relativistic conceptions; only their combination within the conceptual system is new. The book is divided into two parts, one on special relativity and the other on general relativity, each in some respects dependent on the other.