Efforts to formalize qualitative accounts of inference to the best explanation (IBE) confront two obstacles: the imprecise nature of such accounts and the unusual logical properties that explanations exhibit, such as contradiction-intolerance and irreflexivity. This paper aims to surmount these challenges by utilising a new, more precise theory that treats explanations as expressions that codify defeasible inferences. To formalise this account, we provide a sequent calculus in which IBE serves as an elimination rule for a connective that exhibits (...) many of the properties associated with the behaviour of the English expression ‘That... best explains why ... ’. We first construct a calculus that encodes these properties at the level of the turnstile, i.e. as a metalinguistic expression for classes of defeasible consequence relations. We then show how this calculus can be conservatively extended over a language that contains a best-explains-why operator. (shrink)

The present paper advances an analogy between cases of extra-mathematical explanation and cases of what might be termed ‘extra-logical explanation’: the explanation of a physical fact by a logical fact. A particular case of extra-logical explanation is identified that arises in the philosophical literature on time travel. This instance of extra-logical explanation is subsequently shown to be of a piece with cases of extra-mathematical explanation. Using this analogy, we argue extra-mathematical explanation is part of a broader class of non-causal explanation. (...) This has important implications for extra-mathematical explanation, for time travel and for theories of explanation more generally. (shrink)

Motivated by examples, many philosophers believe that there is a significant distinction between states of affairs that are striking and therefore call for explanation and states of affairs that are not striking. This idea underlies several influential debates in metaphysics, philosophy of mathematics, normative theory, philosophy of modality, and philosophy of science but is not fully elaborated or explored. This paper aims to address this lack of clear explanation first by clarifying the epistemological issue at hand. Then it introduces an (...) initially attractive account for strikingness that is inspired by the work of Paul Horwich and adopted by a number of philosophers. The paper identifies two logically distinct accounts that have both been attributed to Horwich and then argues that, when properly interpreted, they can withstand former criticisms. The final two sections present a new set of considerations against both Horwichian accounts that avoid the shortcomings of former critiques. It remains to be seen whether an adequate account of strikingness exists. (shrink)

A relativized concept of a possiblecorrect answer to a why-question is introduced. Acertain procedure of looking for acceptable answers towhy-questions is analyzed in terms of erotetic logic,i.e., the logic of questions.

This work addresses biological explanations and aims to provide a philosophical account which brings together logical-procedural and historical-processual aspects when considering molecular pathways. It is argued that, having molecular features as explananda, a particular non-classical logical language – Zsyntax – can be used to formally represent, in terms of logical theorems, types of molecular processes, and to grasp how we get from one molecular interaction to another, hence explaining why a given outcome occurs. Expressing types of molecular biology processes (...) in terms of the Zsyntax language allows us to represent causal interactions by taking into account their context-sensitivity, and amounts to partly reviving the spirit of the so-called received view of explanation – which aimed to capture scientific explanatory accounts in terms of their logical structure and their appealing to nomological relations. Such a partial revival is pursued by invoking here non-classical deductions and empirical generalisations, which are called to provide the epistemic norms to explain the behavior of molecular pathways. (shrink)

While there has been much discussion about what makes some mathematical proofs more explanatory than others, and what are mathematical coincidences, in this article I explore the distinct phenomenon of mathematical facts that call for explanation. The existence of mathematical facts that call for explanation stands in tension with virtually all existing accounts of “calling for explanation”, which imply that necessary facts cannot call for explanation. In this paper I explore what theoretical revisions are needed in order to accommodate this (...) phenomenon. One of the important upshots is that, contrary to the current consensus, low prior probability is not a necessary condition for calling for explanation. In the final section I explain how the results of this inquiry help us make progress in assessing Hartry Field’s style of reliability argument against mathematical Platonism and against robust realism in other domains of necessary facts, such as ethics. (shrink)

In a contribution to a symposium on “Causality in the Social Sciences,” Lewis Feuer remarks in passing that “Functionalism, in the form which Malinowski gave it, affirms that culture is an ‘organic unity’; it is the principle that in every culture, each custom, belief, and behavioral form ‘represents an indespensible part within a working whole.’” That culture is an integrated and organic unity is a view found quite often in the writings of Malinowski, though he does not maintain it with (...) full consistency. Sometimes he seems to say that a culture is made up of a number of grand institutions, each of which is an integrated unity, though the totality need not be. But whether affirmed or denied this thesis is not the doctrine, characteristic of almost every attempt made by Malinowski to explain cultural phenomena during the last quarter century of his life, which may be properly called “Malinowskian functionalism.” And that the doctrine cited by Feurer is sometimes formulated in such a way that the term “functional” or some variant is used, as in “culture is a functionally integrated organic unity,” makes no difference to my claim. I am not at all certain that the addition of the word “functionally” does anything for the view in question; it surely makes no difference to its scientific sterility. But that apart, the point I wish to make here is that a good many scholars who make references to Malinowski's functionalism have never bothered to discover just what in the world this is. They have been all too ready to cite the vague programmatic pronouncements in which Malinowski's writings abound, while seemingly oblivious to the fact that with rare exception every major attempt by Malinowski to account systematically for some kind of sociocultural phenomena reveals one and the same pattern of explanation. And it is this pattern alone which may be spoken of as Malinowski's method of functional analysis. (shrink)

In the School of Mathematical Sciences at Queen Mary in the University of London we have been running a module that teaches the students to write good mathematical English. The module is for second-year undergraduates and has been running for three years. It is based on logic, but the logic—though mathematically precise—is informal and doesn't use logical symbols. Some theory of definitions is taught in order to give a structure for mathematical descriptions, and some natural deduction rules form a basis (...) for writing mathematical arguments. Alongside this logical material, the students have weekly exercises that involve writing informal explanations of simple mathematical ideas for non-mathematicians. (shrink)

This book about philosophical and methodological problems in psychoanalytic theory is surely one of the best pieces of literature on this subject of recent vintage. The author, a psychiatrist on the faculty of Harvard Medical School, displays considerable logical skill and philosophical sophistication, in addition to the expected familiarity with the psychoanalytic literature. The major purport of the book is a logical and philosophical defense of the claim that psychoanalytic explanations of human behavior--if constructed with proper and adequate regard (...) for relevant clinical data--are methodologically sound and genuinely scientific. One useful and novel feature of Sherwood's argument is the particular type of illustrative case material which he employs: instead of mustering various bits and instances of behavior from large numbers and varieties of cases, Sherwood considers the psychiatric explanation actually given by Freud in one of his recorded clinical case histories--the famous "Karl Lorenz" or "rat man" case. Sherwood devotes two chapters to a detailed description of this case, and an analysis of the logic of Freud's explanations of the behavior presented therein. From the point of view of logical and methodological considerations, there is an obvious advantage in such an approach, for it enables the critic to avoid leveling charges against the theory which might originate simply from extracting portions of explanatory material from their proper context. Sherwood also includes a chapter of criticism of what he calls "the thesis of the separate domain"--the view that there are fundamental differences in the logic of explanations of human behavior, cognition, and other phenomena involving reasons and intentions on the one hand, and other forms of explanation characteristic of the physical sciences, on the other. Philosophically, this is the most mature chapter of the book, and will be of interest to philosophers of mind, as well as philosophers of science, particularly for its criticism of the views of R. S. Peters. Unfortunately, however, Sherwood's argument is not unmarred by serious flaws and deficiencies. These include a highly psychologistic analysis of the logic and structure of explanation whose subsequent use repeatedly involves the author in context-of-discovery vs. context-of-justification confusions. Moreover, an apparent lapse into a non-Humean account of causality in the second section of the fifth chapter leads Sherwood to an unfortunate petitio principii on the issue of causes vs. reasons. Sherwood's critical discussion of the classical "covering-law" model of scientific explanation in the penultimate chapter exhibits numerous failures to come to grips with the essential aspects of the Braithwaite-Hempel-Oppenheim theory. Finally, an important sin of omission: Sherwood completely ignores the highly germane and decisive issues raised by authors such as Nagel and Arthur Pap, who charge the theoretical concepts of psychoanalysis with lack of cognitive and empirical significance. In sum, this is a flawed but eminently worthwhile book in the philosophy of behavioral science.--H. P. K. (shrink)

Argumentation represents a way of reasoning over a knowledge base containing possibly incomplete and/or inconsistent information, to obtain useful conclusions. As a reasoning mechanism, the way an argumentation reasoning engine reaches these conclusions resembles the cognitive process that humans follow to analyze their beliefs; thus, unlike other computationally reasoning systems, argumentation offers an intellectually friendly alternative to other defeasible reasoning systems. LogicProgrammingisacomputationalparadigmthathasproducedcompu- tationallyattractivesystemswithremarkablesuccessinmanyapplications. Merging ideas from both areas, Defeasible Logic Programming offers a computational reasoning system that uses an argumentation engine (...) to obtain answers from a knowledge base represented using a logic programming language extended with defeasible rules. This combination of ideas brings about a computationally effective system together with a human-like reasoning model facilitating its use in applications. (shrink)

Preface for instructors -- Preface for students (you really should read it) -- What is logic about? -- Sentential logic basics -- Sentential logic proofs -- More sentential logic : contradictions, tautologies and assumptions -- Predicate logic basics -- Proofs in predicate logic -- Probability : the basic rules of life -- The theorem of Dr. Bayes -- Probability illusions : why we are so bad at inductive reasoning -- Studies have shown ... or have they? -- Inference to the (...) best explanation -- Rhetoric : the art of persuasion -- Won't get fooled again (fallacies and other foibles) -- Spin, spin, spin (or how not to be a sucker) -- Everything you know is wrong! : pseudoscience and bogus scholarship. (shrink)

These considerations on Carl G. Hempel's and Paul Oppenheim's lucid article “Studies in the Logic of Explanation'”—LE for short—are an attempt to exploit some of the considerable advances made there. I wish to show how these advances may be incorporated into a technique for the investigation of problems of the philosophy of science, which has been called discourse-analytic. This discipline consists essentially in a technique of examining actual texts provided by specialists, such as physicists, psychologists, historians, etc., the task being (...) to discover fundamental logical and semantical features in the discourses under investigation. I am preparing a book on historical explanation, which will contain such case studies of historical texts. (shrink)

Some arguments use ‘generic’, or ‘typical’, objects. An explanation for this idea in terms of ‘almost all’ is suggested. The intuition of ‘almost all’ as ‘but for a few exceptions’ is rendered precise by means of ultrafilters. A logical system, with generalized quantifiers for ‘almost all’, is proposed as a basis for generic reasoning. This logic is monotonic, has a simple sound and complete deductive calculus, and is a conservative extension of classical first-order logic, with which it shares several properties. (...) For generic reasoning, generic individuals are introduced and internalized as generic constants, thereby producing conservative extensions where one can reason about generic objects as intended. A many-sorted version of this logic is introduced to handle distinct notions of ‘large’ subsets. Other possible applications for this logic are indicated. (shrink)

We construct a quantum logic which generates the usual quark states. It follows from this model that quarks can combine only in quark-antiquark pairs and quark (and antiquark) triples. The ground meson and baryon states are also generated and gluons are discussed.

If one were to write a history of the philosophy of science in the spirit of T. S. Kuhn, one would have to consider the model of scientific explanation which Popper proposed and Hempel and Oppenheim developed to be one of the great paradigms of contemporary analytical philosophy of science. This analogue to the historically important paradigms of the individual sciences seems to me to be justifiable for the following reasons: first, the Hempel—Oppenheim model claims universal methodological validity; second, discussions (...) on the problem of explanation have centred on this model for some time; third, the recent cognitive progress in this field has been largely the result of the interrelation between criticism of this model on the one hand and its improvement and explication on the other hand; and lastly, this model stands for a particular comprehension of the problems and possibilities of science, a concept of quite important practical consequence. (shrink)

Modal Homotopy Type Theory: The Prospect of a New Logic for Philosophy provides a reasonably gentle introduction to this new logic, thoroughly motivated by intuitive explanations of the need for all of its component parts, and illustrated through innovative applications of the calculus.

This book constitutes the strictly refereed post-workshop proceedings of the 11th International Workshop on Computer Science Logic, CSL '97, held as the 1997 Annual Conference of the European Association on Computer Science Logic, EACSL, in Aarhus, Denmark, in August 1997. The volume presents 26 revised full papers selected after two rounds of refereeing from initially 92 submissions; also included are four invited papers. The book addresses all current aspects of computer science logics and its applications and thus presents the (...) state of the art in the area. (shrink)

Hempel and Oppenheim have stated in Part III of their paper “Studies in the Logic of Explanation” [2] a set of conditions for deductive explanation. However, their analysis has come under damaging systematic criticisms in a recent paper by Eberle, Kaplan and Montague [1], The principal aim of the present paper is to review the Hempel-Oppenheim analysis and propose a strengthened version of it that avoids the recent criticisms.

The First International Workshop brings together researchers from the theoretical ends of the logic programming and artificial intelligence communities to discuss their mutual interests. Logic programming deals with the use of models of mathematical logic as a way of programming computers, where theoretical AI deals with abstract issues in modeling and representing human knowledge and beliefs. One common ground is nonmonotonic reasoning, a family of logics that includes room for the kinds of variations that can be found in human (...) reasoning. Topics covered: Stable Semantics. Default Logic. AutoEpistemic Logic. Truth Maintenance Systems. Implementation Issues. Diagnosis. Applications. Inheritance Reasoning. Logics of Belief. Inconsistency and Non-Monotonicity. (shrink)

This paper presents a logical Style painting classifier based on evaluated Horn clauses, qualitative colour descriptors and Explanations. Three versions of $\ell $-SHE are defined, using rational Pavelka logic, and expansions of Gödel logic and product logic with rational constants: RPL, $G$ and $\sqcap $, respectively. We introduce a fuzzy representation of the more representative colour traits for the Baroque, the Impressionism and the Post-Impressionism art styles. The $\ell $-SHE algorithm has been implemented in Swi-Prolog and tested on 90 (...) paintings of the QArt-Dataset and on 247 paintings of the Paintings-91-PIB dataset. The percentages of accuracy obtained in the QArt-Dataset for each $\ell $-SHE version are 73.3%, 65.6% $) and 68.9% $). Regarding the Paintings-91-PIB dataset, the percentages of accuracy obtained for each $\ell $-SHE version are 60.2%, 48.2% $) and 57.0% $). Our logic definition for the Baroque style has obtained the highest accuracy in both datasets, for all the $\ell $-SHE versions. An important feature of the classifier is that it provides reasons regarding why a painting belongs to a certain style. The classifier also provides reasons about why outliers of one art style may belong to another art style, giving a second classification option depending on its membership degrees to these styles. (shrink)

We propose a formal framework for interpretable machine learning. Combining elements from statistical learning, causal interventionism, and decision theory, we design an idealisedexplanation gamein which players collaborate to find the best explanation(s) for a given algorithmic prediction. Through an iterative procedure of questions and answers, the players establish a three-dimensional Pareto frontier that describes the optimal trade-offs between explanatory accuracy, simplicity, and relevance. Multiple rounds are played at different levels of abstraction, allowing the players to explore overlapping causal patterns of (...) variable granularity and scope. We characterise the conditions under which such a game is almost surely guaranteed to converge on a (conditionally) optimal explanation surface in polynomial time, and highlight obstacles that will tend to prevent the players from advancing beyond certain explanatory thresholds. The game serves a descriptive and a normative function, establishing a conceptual space in which to analyse and compare existing proposals, as well as design new and improved solutions. (shrink)

The Joint International Conference on Logic Programming, sponsored by the Association for Logic Programming, is a major forum for presentations of research, applications, and implementations in this important area of computer science. Logic programming is one of the most promising steps toward declarative programming and forms the theoretical basis of the programming language Prolog and its various extensions. Logic programming is also fundamental to work in artificial intelligence, where it has been used for nonmonotonic and commonsense reasoning, expert systems implementation, (...) deductive databases, and applications such as computer-aided manufacturing. Krzysztof R. Apt is project leader at the Centre for Mathematics and Computer Science in Amsterdam and part-time Professor in Computer Science at the University of Amsterdam. Topics covered: Theory Foundations. Programming Languages. Implementation. Programming Methodologies and Tools. Applications. Deductive Databases. Artificial Intelligence. Parallelism. (shrink)

Abductive Reasoning: Logical Investigations into Discovery and Explanation is a much awaited original contribution to the study of abductive reasoning, providing logical foundations and a rich sample of pertinent applications. Divided into three parts on the conceptual framework, the logical foundations, and the applications, this monograph takes the reader for a comprehensive and erudite tour through the taxonomy of abductive reasoning, via the logical workings of abductive inference ending with applications pertinent to scientific explanation, empirical progress, pragmatism and belief revision.

Three-valued (strong-Kleene) modal logic provides the foundation for a new approach to formalizing causal explanation as a relation between partial situations. The approach makes fine-grained distinctions between aspects of events, even between aspects that are equivalent in classical logic. The framework can accommodate a variety of ontologies concerning the relata of causal explanation. I argue, however, for a tripartite ontology of objects corresponding to sentential nominals: facts, tropes (or facta or states of affairs), and situations (or events). I axiomatize the (...) relations and use canonical models to demonstrate completeness. (shrink)

In this paper we discuss a view of the Machine Learning technique called Explanation-Based Learning (EBL) or Explanation-Based Generalization (EBG) as a process for the interpretation of vague concepts in logic-based models of law.The open-textured nature of legal terms is a well-known open problem in the building of knowledge-based legal systems. EBG is a technique which creates generalizations of given examples on the basis of background domain knowledge. We relate these two topics by considering EBG''s domain knowledge as corresponding to (...) statute law rules, and EBG''s training example as corresponding to a precedent case. (shrink)

In this paper I will develop a view about the semantics of imperatives, which I term Modal Noncognitivism, on which imperatives might be said to have truth conditions (dispositionally, anyway), but on which it does not make sense to see them as expressing propositions (hence does not make sense to ascribe to them truth or falsity). This view stands against “Cognitivist” accounts of the semantics of imperatives, on which imperatives are claimed to express propositions, which are then enlisted in (...) class='Hi'>explanations of the relevant logico-semantic phenomena. It also stands against the major competitors to Cognitivist accounts—all of which are non-truth-conditional and, as a result, fail to provide satisfying explanations of the fundamental semantic characteristics of imperatives (or so I argue). The view of imperatives I defend here improves on various treatments of imperatives on the market in giving an empirically and theoretically adequate account of their semantics and logic. It yields explanations of a wide range of semantic and logical phenomena about imperatives—explanations that are, I argue, at least as satisfying as the sorts of explanations of semantic and logical phenomena familiar from truth-conditional semantics. But it accomplishes this while defending the notion—which is, I argue, substantially correct—that imperatives could not have propositions, or truth conditions, as their meanings. (shrink)

In this paper we examine the theory of historical explanation presented by Arthur Danto in his book, Analytical Philosophy of History (1965).Our thesis is that Danto is mistaken in his assertion that a phenomenon can be covered by a general law only insofar as we produce a description of it which contains no uneliminable particular designations of it. It is possible to cover such particular statements with general laws provided one can bridge the logical gap between the two types of (...) sentence with other statements which need not be redescriptions of the phenomenon but can be independently established premises for a deductive argument.We further show that some of the analogies which Danto attempts to make between deduction and narrative are mistaken because of errors in Danto's understanding of logical theory, specifically, Danto's notion that no predicate may appear in the conclusion of a deductive argument which is not antecedently contained in the premises and his claim that the same variable must be replaced by the same constants throughout an argument. (shrink)

Donagan has argued (a) that the covering law model of explanation does not apply in certain cases in historical explanations; (b) that situational logic explanations do apply, and (c) that situational logic explanations are fundamentally different from covering law explanations. It is argued that (b) is false as Donagan construes situational logic explanations. Once situational logic explanations are correctly construed they are similar to Hempel's rational explanations in covering law forms — hence (c) (...) is false if situational logic explanations are correctly interpreted. Finally it is argued that one major reason Donagan gives for (a) is mistaken. (shrink)

Let Essentialism be the view that at least some object has at least some property essentially. And let Relative Essentialism be the view that Essentialism is true, but that for any object that has any property essentially, it has it essentially only relative to the value of some parameter. Meghan Sullivan has recently put forward a promising new version of Relative Essentialism, according to which the relevant parameter is an explanatory framework. We argue that despite its promise, Sullivan's version unfortunately (...) fails, due to the mismatch between the logic of essentiality and the logic of explanation. (shrink)

Van Fraassen argues that explanatory power cannot be a conformational virtue. In this paper I will show that informational features of scientific theories can be positively relevant to their levels of conformation. Thus, in the cases where the explanatory power of a theory is tied to an informational feature of the theory, it can still be the case that the explanatory power of the theory is positively relevant to its level of confirmation.

"Explanation and Understanding" (1971) by Georg Henrik von Wright is a modern classic in analytic hermeneutics, and in the philosophy of the social sciences and humanities in general. In this work, von Wright argues against naturalism, or methodological monism, i.e. the idea that both the natural sciences and the social sciences follow broadly the same general scientific approach and aim to achieve causal explanations. Against this view, von Wright contends that the social sciences are qualitatively different from the natural (...) sciences: according to his view, the natural sciences aim at causal explanations, whereas the purpose of the social sciences is to understand their subjects. In support of this conviction, von Wright also puts forward a version of the so-called logical connection argument. -/- Von Wright views scientific explanation along the lines of the traditional covering law model. He suggests that the social sciences, in contrast, utilize what he calls “practical syllogism” in understanding human actions. In addition, von Wright presents in this work an original picture on causation: a version of the manipulability theory of causation. -/- In the four decades following von Wright’s classic work, the overall picture in in the philosophy of science has changed significantly, and much progress has been made in various fronts. The aim of the contribution is to revisit the central ideas of "Explanation and Understanding" and evaluate them from this perspective. The covering law model of explanation and the regularity theory of causation behind it have since then fallen into disfavor, and virtually no one believes that causal explanations even in the natural sciences comply with the covering law model. No wonder then that covering law explanations are not found in the social sciences either. Ironically, the most popular theory of causal explanation in the philosophy of science nowadays is the interventionist theory, which is a descendant of the manipulability theory of von Wright and others. However, this theory can be applied with no special difficulties in both the natural sciences and the social sciences. -/- Von Wright’s logical connection argument and his ideas concerning practical syllogisms are also critically assessed. It is argued that in closer scrutiny, they do not pose serious problems for the view that the social sciences too provide causal explanations. In sum, von Wright’s arguments against naturalism do not appear, in today’s perspective, particularly convincing. (shrink)

In this paper I argue that historiography employs causal narrative explanations just as other historical sciences such as evolutionary biology or paleontology do. There is a logic of explanation common to all these sciences that centers on causal explanation of unique and unrepeatable events. The explanandum of historiography can further be understood as mechanism in the sense developed by Stuart Glennan and others in recent years. However, causal explanation is not the only way historiography relates to the past. Arthur (...) Danto has given us the theoretical tools to differentiate between causal narratives and conceptual colligations, with both playing a pivotal role in historiography even though Danto himself has not expressed that thought clearly. (shrink)

Treating consciousness as awareness or attention greatly underestimates it, ignoring the temporary levels of organization associated with higher intellectual function (syntax, planning, logic, music). The tasks that require consciousness tend to be the ones that demand a lot of resources. Routine tasks can be handled on the back burner but dealing with ambiguity, groping around offline, generating creative choices, and performing precision movements may temporarily require substantial allocations of neocortex. Here I will attempt to clarify the appropriate levels of explanation (...) (ranging from quantum aspects to association cortex dynamics) and then propose a specific mechanism (consciousness as the current winner of Darwinian copying competitions in cerebral cortex) that seems capable of encompassing the higher intellectual function aspects of consciousness as well as some of the attentional aspects. It includes features such as a coding space appropriate for analogies and a supervisory Darwinian process that can bias the operation of other Darwinian processes. (shrink)

In this work, it is argued that one of the foundations of NiklasLuhmann’s theory of social systems, namely that it has no ontology, would prevent the elaboration of explanations in sociology. Because the theory has a formal-logical foundation, which does not presuppose ontology, there are insurmountable obstacles to achieving this objective. For this reason, it is valid to wonder about the merit of a theory that, after 20 years, insists on not aligning itself with ontological premises in a robust (...) way and suggests, therefore, a refusal to integrate sociology within the set of factual sciences. However, we think that the richness of Luhmann’s work allows a dialogue with the mainstream of contemporary theoretical practice. Three rules about what “should not be done” are revalidated from this analysis to philosophically base a theory in sociology and a key suggestion to overcome the problem of explanation in Luhmann’s sociology: social science seeks and directs its activity towards discovery and the use of substantive, real distinctions that also enrich the factual content of statements about social reality. (shrink)

Anyone, today, with even a slight interest in the methodology of science will be aware of the heated debate which has raged in regard to the thesis of the logical symmetry between explanation and prediction, which is entailed by the hypotheticodeductive account of scientific theory. The symmetry thesis, which received its classical exposition in a well-known article by Hempel and Oppenheim [2], has been subject to a steadily growing criticism by several eminent thinkers. My intention, in this article, is to (...) argue that the current reaction to the Hempel-Oppenheim position, as exemplified by Professors Hanson, Scriven, et al., represents a retrograde movement in the philosophy of science, which, as the number of its converts grows, could undermine the progress, which has been accomplished in the broad tradition that extends from Mach and Poincaré through the Vienna Circle to the present day. Specifically, it is my contention that the aforementioned reaction is symptomatic of a contemporary trend in the direction of irrationalism which, of all branches of philosophy, the philosophy of science should seek to dispel rather than to foster. For the sake of brevity, I propose to focus my remarks wholly on the original widely read article of Hanson on this subject [1]. That I single out this particular source should not be taken to belie the admiration I hold for the masterful scholarship of its author. (shrink)