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“In opposition to common sense I dare to imagine some movement of the Earth; … since mathematicians have not (yet) agreed with each other, I was moved to think out a different scheme …; by supposing the Earth to move, demonstrations more secure than those of my predecessors (could) be found for the revolutions of the… spheres… all (celestial) phenomena follow from this (supposition).” Nicholas Copernicus, On the Revolutions of the Heavenly Spheres, Preface and Dedication to Pope Paul III.1

There, too often, the matter is left, B feeling that A is profoundly unclear about what he is asking for, and A reckoning that B’s refusal to have his difficulty indicates only a lack of depth and a narrowness of technique. A’s position is quite shocking, despite the fact that many discussions (both inside and outside philosophy) often come perilously close to it. Because if you and I can never know whether we are having the same experience in those situations where we both confront, e.g. a stoplight, and respond by saying “Red,” then we can certainly never know whether we are having the same experience when we are looking at triangles, or chairs, or tables, or other people, or any of the other philosophical furniture of the external world. To have the doubt which A expresses just is to entertain the most radical kind of solipsism, although many seem to have had the former without explicitly entertaining the latter. It is hardly satisfactory to point out here, as some recent philosophers, like B above, seem to have thought it sufficient to do, that the question is not a soluble one. This is precisely what A is claiming. Discussions often conclude therefore in agreeing that the difficulty is insoluble and then proceed to construct theories as to how it is that A and B ever manage to agree upon so much in the world, despite their disagreements about “basic” visual experience. Here words like “convention”, “agreement”, “stipulation”, and “ostensive”, are exercised rather heavily. We can, apparently, never really know that we have the same “inner” visual experiences. But we can, by various sorts of arbitrary agreements and conventional decisions, proceed to act as if we do have the same experiences. The value of the agreements and decisions is assessed pragmatically. If we can all succeed in managing our affairs in the world by agreeing that X and deciding that Y, then in so far do we rely on X and Y.

Consider ‘Hume’s dictum’: that from a necessary proposition nothing contingent follows — and vice versa. The effect of this on speculative metaphysics is devastating, although few practicing metaphysicians realize how utterly their position has been devastated. I will spell this out by drawing the profound logical moral of Hume’s dictum.

As Marcus Aurelius once said: “Those who come on the third night during rain, are truly lovers of wisdom.” It isn’t absolutely certain that he said that, but there is some scholarly dispute about it. Last night I considered the shaping of an idea. The idea was this: that flight might be thought of as a scientifically understandable, objectively tractable, and practically achievable phenomenon. Through the sorts of work that Newton and the other ideal hydrodynamicists accomplished, they did shape such an idea, the idea of a discipline concerned with the dynamics of gases like air. Tonight we won’t talk about the shaping of an idea, but rather the idea of a shape. And the shape we will be discussing tonight by slow degrees will be nothing other than the airfoil shape which, as shapes go, seems to me one of the more influential that we have had in our time. There is evidence in Leonardo’s little tract on the flight of birds which indicates that he understood something of the curvature in a bird’s wing. It can even be supposed that he was not wholly in the dark concerning the air flow over the top side of such a convex shape, though this is just conjecture. However, you must remember Sir George Cayley, the man who made the remarkable statement that the whole problem in aerodynamics is simply to make a surface support a given weight by the application of power to the resistance of the air. Shortly after he made that statement, he considered what he called the concave wing of a bird. He explained its purpose as follows: “the air being obliged to mount along the convexity of the surface, creates a slight vacuity immediately behind the point of separation.” What he means by vacuity behind the point of separation is a topic we will be considering shortly. But Cayley said this in 1809, almost 100 years before the actual advent of powered flight. His passing reference to the slight vacuity above the wing appears to our 20-20 hindsight as the vision supreme in the story of flight. Because this is truly the germ of the full explanation of what all air foils are meant to do. Whether they flop or are rigid or whether they rotate horizontally as helicopter blades do or spin vertically as do orthodox propeller blades.

“F is a good reason for C”, if true at all, could not but have been true — even when F and C are contingent. Much in this claim is true. Much is misleading. Let us sort this out and, en route, discuss a certain pattern of inference, and “the problem of induction”.

Contemporary Psychological Behaviorists argue against the existence of mental events in ways that are but little more refined than those of Watson, Lashley, and others forty years ago. The orthodox case stated by today’s psychologists against the possibility of a science of mental events is inconclusive. This is because their attack is usually based on factual considerations, instead of being, what it ought to be, a conceptual analysis of the idea of a mental event. This article seeks to disclose some weaknesses in the standard pattern of attacks on Introspection. It does this by defending the latter (i.e. Introspection) against such factually-orientated criticisms as those of Watson, Lashley, Hull and Skinner. It then challenges Introspection as it should be attacked; not externally with counterfacts, but internally with demonstrations of what is untenable in the very concept of a science of private events called “mental”.

The trial of Galileo has long been used by historians, by philosophers, and by scientists as a classic example of intellectual martyrdom, resembling somewhat the trial of Socrates. Since that is the way “the Galileo story” is usually represented, it turns out replete with villains and heroes. The scenario depends on who the scriptwriter happens to be.

A loose analogy relates the work of Laplace and Hilbert. These thinkers had roughly similar objectives. At a time when so much of our analytic effort goes to distinguishing mathematics and logic from physical theory, such an analogy can still be instructive, even though differences will always divide endeavors such as those of Laplace and Hilbert.

An agnostic maintains himself in a state of perfect doubt concerning God’s existence, a position I regard as unsound. The agnostic achieves his equipoise of dubiety only by shifting his ground where logic requires him to stand fast.

In thirty years the science of elementary particles has made few achievements compared with its unsuccessful essays. The recent works of Schwinger, Tomonaga, Feynman and Dyson, however, have had some success.1 We have here a hint that progress is being made on the formal side of the discipline — though even this work is profoundly disturbing in some of its purely mathematical aspects.2 There could be no better time to review the situation from a physical and philosophical standpoint, even if this proves to be an over-ambitious undertaking.

My objective here is vulnerable to some spurious semantics. I aim to delineate how the development of physical theory in the later nineteenth century was essentially dependent on the reflections and discoveries of Chemists, Biologists and Mathematicians. But when one alludes to some professional Chemist or Biologist as having affected the history of physics, it can always be countered “to that extent he was doing physics, he was being a physicist”. Thus when Urey helped to separate U235 from U238, and when he invoked theoretical thermodynamics to determine the age of the solar system, he might be said then to have been doing physics – despite being a Nobel laureate in chemistry. And when Pauling applied quantum theory to studies of complex substances, and when he considered the rotation of molecules in crystals – he too was apparently being a physicist, although, again, a Nobel laureate in chemistry. So also of great moments in the work of Nernst, Boltzmann, Helmholtz, Faraday, Young… and so on. That is, one can always say that whatever helps physics is physics. But this is 20–20 hindsight focused to the point of tautology. For it suggests that a Biologist might one day awaken with the pronouncement “I think I’ll do some physics today”; a Chemist or Mathematician might muse “this problem will put demands on the physicist in me”. The history of science can be thus chopped up only by destroying the organic interplay between disciplines, an interplay which constitutes the very pulse of scientific research. The picture of disciplines rigidly fixed as to content, and of scientists as compartmentalized thinking machines – both pictures are unreliable reflections of the ways in which problems and their solutions have actually shaped the history of science. Just as being a ‘natural philosopher’ in the seventeenth century was not identical with being a theoretical physicist in the twentieth, so also the divisions between biology, chemistry and physics in the nineteenth century may not always have been drawn along the same lines as we should sketch them today. In short, one must be an historian when tracing the lines of development through nineteenth century science. Not everything that is embraced today in physics texts began in physics labs, or in the minds of professional physicists. Therefore, I propose to correlate the contributions of scientists now known to us as important in the histories of chemistry and biology-with moments in the development of nineteenth century physics. Should one then choose to dub all such individuals as really physicists, a la bonne heure.

Within the past decade there has grown an acute and highly articulate group of critics of the orthodox interpretation of quantum theory,—the so-called “Copenhagen Interpretation.” The writings of people like Bopp, Janossy, and particularly Bohm and Feyerabend, must be taken very seriously indeed. The future of some important discussions in the philosophy and the logic of science rests with these individuals. But they have, in their own writings, occasionally matched the inelegancies of Bohr and Heisenberg with as many inelegancies of their own. The present paper is meant to present a quintet of considerations which may possibly lead to a reassessment of the issues between Bohr, Heisenberg, and their critics, especially Bohm and Feyerabend.

The conceptual excitement of science often seems geared only to work in contemporary physics. Thus, philosophers regularly discuss current cosmology, relativity, or the foundations of microphysics. In these areas one's philosophy is stretched and strained far beyond what our ancestors might have anticipated. Historians of science have also focused attention on past events by remarking their analogies and similarities with perplexities in physics today.But there are statements, hypotheses and theories of the past which are rewarding in themselves, without having to be referred to the agonies which now confound quantum theory and cosmology. Specifically, the First Law of Motion—the “Law of Inertia”—this has everything a logician of science could look for. Understanding the complexities and perplexities of this fundamental mechanical statement is in itself to gain insight into what theoretical physics in general really is. With this in view a study of the law is undertaken.

The theoretical and experimental context within which the “Copenhagen Interpretation” of quantum theory was generated is underemphasized by recent critics of the Bohr-Heisenberg philosophy. When an interpretation of a theory has been as successful as this one has been, there is little practical warrant for the “alternative interpretations” which have, since Bohm, been receiving prominence. Indeed, these are not even genuine alternatives; although rich in provocative prose, they provide not a scrap of algebra with which to organize the practical physicist's thinking. Several objections to the Bohr interpretation are critically examined, as is also a particular use of the correspondence principle which has seemed to cast doubt on the Copenhagen ideas.

In thirty years the science of elementary particles has made few achievements compared with its unsuccessful essays. The recent works of Schwinger, Tomonaga, Feynman and Dyson, however, have had some success. We have here a hint that progress is being made on the formal side of the discipline—though even this work is profoundly disturbing in some of its purely mathematical aspects. There could be no better time to review the situation from a physical and philosophical standpoint, even if this proves to be an over-ambitions undertaking.

Is there such a thing as a ‘Logic of Discovery’? Do we even have a consistent idea of such a thing? The approved answer to this seems to be “No.” Thus Popper argues (The Logic of Scientific Discovery) “The initial stage, the act of conceiving or inventing a theory, seems to me neither to call for logical analysis nor to be susceptible of it.” (p. 31.) Again, “… there is no such thing as a logical method of having new ideas, or a logical reconstruction of this process.” (p. 32.) Reichenbach writes that philosophy of science “… cannot be concerned with [reasons for suggesting hypotheses], but only with [reasons for accepting hypotheses].” (Experience and Prediction, p. 382.) Braithwaite elaborates: “The solution of these historical problems involves the individual psychology of thinking and the sociology of thought. None of these questions are our business here.” (Scientific Explanation, pp. 20, 21.)

(1960). Is there a logic of scientific discovery? Australasian Journal of Philosophy: Vol. 38, No. 2, pp. 91-106.

THIS remark is often repeated in textbooks and manuals on modem physics. It is singled out here for several reasons: (i) Its innocent, matter-of-fact tone conceals one of the most intricate and interesting chapters in the history of scientific discovery; (2) it encourages an analogy between discoveries within microphysics, and quite noncomparable discoveries within, e.g., natural history; and (3) the actual discovery of the positron, in all its dimensions, constitutes an instructive example of the interplay of theory and experiment within physical science, one of the best a historian, or logician, of science could ever hope for. The positron packet can be dipped into in three different ways. The physicist reaches into this complex of concepts to facilitate his thinking within e.g. quantum field theory, or the experimental study of cosmic rays. The historian of physics attends to the exciting interplay of ideas within the microphysics of the 1920s--the better to perceive the initial resistance to the positron-idea, as well as to trace the theoretical evolution which resulted in the claim that positive electrons exist. The logician will focus upon the internal structure of the arguments and concepts actually employed, and still being employed, by those physicists who have played major roles in this story. In the history of science the positron discovery constitutes at once one of the richest, and yet one of the most neglected, areas of inquiry. The discovery of the positive electron was a discovery of three different particles. I choose to put the matter this way, rather than to

For five years a new subject has been taught within the Natural Sciences Tripos at Cambridge University. I have been associated with the development of this course, and I should like to tell you something of our objectives, and of the difficulties we have experienced.

A loose analogy relates the work of Laplace and Hilbert. These thinkers had roughly similar objectives. At a time when so much of our analytic effort goes to distinguishing mathematics and logic from physical theory, such an analogy can still be instructive, even though differences will always divide endeavors such as those of Laplace and Hilbert.

1. The philosophical version of the primary-secondary distinction concerns (a) the ‘real’ properties of matter, (b) the epistemology of sensation, and (c) a contrast challenged by Berkely as illusory.The scientific version of the primary-secondary distinction concerns (a′) the physical properties of matter, (b′) a contrast essential within the history of atomism, and (c′) a contrast challenged by 20th century microphysics as de facto untenable.2. The primary-secondary distinction within physics can be interpreted in two ways:a. it can refer to content; e.g. ‘Matter has the properties of mass, shape, density… etc. — it only appears to have the properties of warmth, fragrance, etc.’ Or,b. it can refer to form; e.g. ‘Whatever properties our best theories accord to primary matter, e.g., electrons, these are by definition primary. All other properties of, e.g., macromatter, are derivative.’Concerning 2.a., this interpretation is simply false when 17th, 18th, or 19th century values for the property-variables are introduced. Concerning 2.b., this either uninformative or misleading. It is uninformative when it constitutes no more than a decision to use the word ‘primary’ as an umbrella-word for all the properties contemporary micro-physics accords to fundamental material particles, whatever these may be. It is misleading when it turns on an implicit contrast between certain properties particles may be said to have when ‘harnessed’ to a detector, and certain other properties these particles have when free and unharnessed to any detector. This contrast does not exist. Quantum-theoretic information is always about particles-and-their-detectors-in-combination. Dissolve this combination and you destroy any possible knowledge of the particle. Hence the notion of ‘completely objectifiable properties of particles’ is in principle unsound. (Cf. Hanson, American Journal of Physics, 27 January, 1959).

an attack on anything implicit in our ordinary ways of speaking, and that (ii) the view that certain perceptible qualities are dispositional (and therefore not 'in' things) is not inconsistent with anything implicit in our ordinary ways of speaking. (iii) What is directly touched by this view is the Objectivist account of perception. (iv) The expression of the Objectivist view is facilitated by a deviation from ordinary ways of speaking. Since the Objectivist view also makes assumptions that have little immediate plausibility, we may conclude that to represent the consequences of attention to the scientific facts as showing that certain perceptible qualities are not 'in' things, leaves their philosophical relevance to be established.

concept can be the reference of a predicate and that it cannot be the reference of a proper name are, when taken together, inconsistent." (Pp. 60-61.) Thus, the semantical paradox is not Frege's, but Fisk's in his application of a general symbolic formula to Frege's statements of his basic principles. Nevertheless, it is not true, as Fisk holds, that either the paradox is generated (his sentence (9) which contradicts (6) is "sanctioned"), "or it is impossible to raise the general question whether predicates do or do not refer to objects." (P. 59.) As has been indicated the paradox is not generable in Frege's logic and Frege does indeed raise and answer the general question whether predicates do or do not refer to objects. He determined generally that the whole reference of a predicate can never be an object. What Frege cannot do and what Fisk imposes on him is a particular way of asking this question in terms of the use of 'A refers to x.! Frege quite honestly indicates the difficulties of this approach and avoids getting trapped in the use of it.