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Book Information The Blackwell Guide to Philosophical Logic. Edited by Lou Goble. Blackwell Publishers. Oxford. 2001. Pp. x + 510. Paperback, £16.99.

A N Prior has a special place in the history of postwar philosophy for his highly original work at the intersection of logic and metaphysics. His logical innovations have found many applications in the areas of philosophical logic, mathematics, linguistics, and, increasingly, computer science. In addition, he made seminal contributions to debates in metaphysics, particularly on modality and the nature of time. This volume presents a selection of current research in the areas that were of most interest to Prior: temporal and tense logic, modal logic, proof theory, quantification and individuation, and the logic of agency. Both title and contents reflect Prior's view that logic is 'about the real world', and the orientation of the volume is towards the application of logic, in philosophy, computer science, and elsewhere. Following Prior, modal syntax is now widely applied to the formalization of a variety of subject matters, and tense logic has found numerous applications in computing, for example in natural language processing, logical deduction involving time-dependent data, program-verification, and VLSI. A special feature of the volume is the inclusion of three hitherto unpublished pieces by Prior on modal logic and the philosophy of time, along with a complete bibliography of Prior's published philosophical writings.

Ray Kurzweil (Letters, Science 's Compass, 16 July, p. [339][1]) responds to my review ( Science 's Compass, 30 Apr., p. [745][2]) of his The Age of Spiritual Machines (Viking, New York, 1999) as follows. 1. 1) My review “mires the reader in obscure and misleading factual objections.” Kurzweil attempts a history of computing; in history, facts matter. He challenges only one of my historical objections, concerning the UNIVAC computer. His book, in an entry labeled “1950,” says, “Eckert and Mauchley develop UNIVAC, the first commercially marketed computer. It is used to compile the results of the U.S. census” (p. 269). In fact UNIVAC was under more or less continuous development from 1947; it was not the first commercially marketed computer, nor was it operational until 1951. 2. 2) I “drag out old anti-artificial-intelligence (AI) arguments.” I do not. Rather, I hold that make-believe about basic conceptual issues, such as we find in Kurzweil's book, are hindering AI. 3. 3) I complain “about anthropomorphizing, but there is no harm….” In AI, anthropomorphizing leads to an emphasis on human qualities that are irrelevant to, and a distraction from, the real aims of AI. 4. 4) My review “ignores [the book's] salient arguments….” I do not detect any, only fantasy, Kurzweil's own “laws” of physics, unjustified assertions, and factual errors. His letter is no different. For example, Kurzweil insists that Wittgenstein's Tractatus is about the brain, supporting this with a fallacious argument. In fact, the Tractatus is a technical work of symbolic and philosophical logic and abstract metaphysics and has nothing to say about the brain. Moreover, when Wittgenstein later did discuss the brain, he denied precisely Kurzweil's argument, that to talk about “thinking” or “knowing” is to talk about brain activity. Kurzweil also says that “there is nothing to prevent these efforts [modest connectionist experiments] from scaling up to the entire human brain.” How could he, or anyone else, possibly know this, given the vast discrepancy in scale that is involved (there are perhaps as many as 1014 neurons in the human brain)? [1]: /lookup/doi/10.1126/science.285.5426.337g [2]: /lookup/doi/10.1126/science.284.5415.745

It is amusing to see how quickly evolutionists fall into the trap of scientism (which is religiosity) when they declare that the theory of evolution has claim to “the truth.” No reputable physicist or chemist would be presumptuous enough to characterize scientific discoveries, at least in the hard sciences, as “truth that will make us free,” even when the evidence has become overwhelming (as it has for the Second Law of Thermodynamics or Einstein's theory of general relativity). The editorial “Darwin's more stately mansion” by Stephen Jay Gould ( Science 's Compass, 25 June, p. [2087][1]) is a sermon in praise of the “evolutionary nexus,” as he calls it. If Gould chooses to believe that he belongs to the species Homo sapiens , where he is “a little higher than the apes…,” that is his prerogative. I and many of my physicist colleagues see intelligent design everywhere in nature and, compelled by the weight of such evidence, choose to believe that we are made “a little lower than the angels…,” a quote which Gould takes from Psalm 8, but quickly dismisses as a “crutch.” I ought to thank Gould for reminding me of the difference between good science and scientism. We should all take seriously the principle that “the confidence expressed in any scientific conclusion should be directly proportional to the quantity and quality of evidence for the conclusion” ([1][2]). # Science and "Truth" {#article-title-2} Gould is right that the public would be better off if they understood the basis of all biological science. But I disagree that evolution, as a scientific theory, is “validated,” at least in the classic sense of the scientific method. Evolution, when construed as the hypothesis that the properties of all species are set by the process of natural selection through survival and reproduction of the fittest, is, at best, a barely testable hypothesis. Scientific hypotheses are most securely “validated” when (i) they make successful predictions; (ii) there are conceivable observations that could, in principle, refute them, but have not; and (iii) there is a comparably sensible competitor theory that is faring worse. None of these conditions is met by evolution, at least when it is construed as a statement about the natural world. Don't get me wrong: I believe in evolution. But I would have a much stronger reason for my belief if Gould or others made a verifiable, falsifiable prediction about some as-yet-unobserved aspect of the natural world (and I don't mean about selectively bred fruit flies in laboratories) and put the hypothesis that evolution occurs by natural selection through survival of the fittest to an a priori test. # Science and "Truth" {#article-title-3} ![Figure][3] Random or intelligent design?CREDIT: REGINATO, FRANCESCO/TIB Gould's editorial, with its many allusions to religious images, is puzzling. Has Gould appropriated the terminology of traditional religion as a prelude to creating an evolutionary religious faith? Or does he (consciously or unconsciously) recognize the existence of realities that transcend the empirical facts and that can only be expressed by words like “spirit” or “soul”? If it follows from the statement “evolution is true” that “the comforts and crutches of traditional religious belief are false,” then it behooves the evolutionary scientist to make his or her case. If “evolution is true” logically implies that “our species is not God's created image,” then say so. Otherwise, a “pastoral effort” to win the minds and hearts of unbelievers that removes one crutch to replace it with another is open to severe criticism. (And do not forget the multitude who accept both the theory of evolution and the idea of man's spiritual destiny.) 1. [↵][4]Teaching Science in a Climate of Controversy (American Scientific Affiliation, Ipswich, MA, 1993), p. 23 (p. # Science and "Truth" {#article-title-4} Although we probably can only ascribe spiritual significance to the biblical myth of creation, we must also be aware that man's thought and imagination are in a timeless realm—we cannot correlate either with what is happening in an hour in the timepiece on our wrist or over billions of years. Gould, therefore, should be more careful about overreaching with his laments and conclusions. [1]: /lookup/doi/10.1126/science.284.5423.2087 [2]: #ref-1 [3]: pending:yes [4]: #xref-ref-1-1 "View reference 1 in text"

This book represents a welcome departure from the past. Many readers in AI avoid looking at books on philosophy and artificial intelligence, at least after seeing one or two of the genre. The reason for this disinterest is aptly captured by Thomason in his introduction to the present volume, which expands on a special issue of the Journal of Philosophical Logic published in 1988.

The doctrine of middle knowledge was developed by the Spanish Jesuits Luis de Molina and Francisco Suarez in the late sixteenth century, and immediately became the subject of fierce controversy, being bitterly opposed by the Dominicans, especially Domingo Bafiez and Diego Alvarez, and requiring the intervention of the Vatican (in 1607) to cause the bitterness to subside. As recent work has shown, the intellectual interest of the doctrine extends far beyond that of an inhouse debate in the Catholic Church of the Counter-Reformation; for it touches on issues of central importance not only in analytic theology, but also in philosophical logic. According to Molina, there are three moments in God's foreknowledge of the history of the world which He creates.' These moments are not to be thought of as stages in a temporal series, but as ordered by the relation of logical or conceptual dependence of later on earlier.2 In the first moment, God knows by natural knowledge all metaphysically necessary propositions. These include not merely truths of logic and mathematics, and natural laws, but also facts about which contingent states of affairs are possible, since that a state of affairs is possible is itself a necessary truth. God's natural knowledge would suffice to equip Him with complete foreknowledge of the history of His creation, if the world He created were entirely deterministic, and if He undertook to refrain from free intervention in that world. The creation

There is a view that is popular in the literature on philosophical logic according to which some sentences ('statives') are about states, whereas others ('nonstatives') are about events. I will take it for granted that there is some truth to this view, and address the issue of what a theory of semantics might look like that encapsulates it. How might a theory of language construe some sentences as being about events and others as being about states, and what might be the evidence in favour of or against such a theory? I think that there is such a theory, and that there is evidence in its favour; that is the topic of this paper. I begin with an old proposal, due to Frank Ramsey, according to which some rather ordinary sentences of English have logical forms which assert the existence of events. In his essay 'Facts and Propositions', Ramsey says: The connection between the event that was the death of Caesar and the fact that Caesar died is, in my opinion, this: 'That Caesar died' is really an existential proposition, asserting the existence of an event of a certain sort, thus resembling 'Italy has a king', which asserts the existence of a man of a certain sort. (Ramsey [1960] p. 141.) More recently Donald Davidson, extending a view of Hans Reichenbach's, defends a similar thesis about certain sentences of English. (Davidson [1967]) Davidson explicitly limits his account to a subset of English sentences; the key to this limitation is in the title of his essay, 'The Logical Form of Action Sentences'. This raises various questions: Is some version of the 'underlying event' account plausible for some sentences of English, as Ramsey suggests? If so, is it plausible for all of them, or only for 'action sentences', as Davidson (implicitly) suggests? More specifically, can such a theory be extended to stative sentences? My task in this paper is to answer these questions. In

Philosophical logic has its problem-children; and among these the Principle of Substitutivity of codesignating expressions the linguistic spawn of Leibniz's Law has achieved a place of prominence. It has become increasingly apparent that a certain style of linguistic analysis, which seeks to impose formal regimentation ruled by the constraints of classical quantification theory, does not yield results with the kind of uniformity and elegance one should hope for from a satisfying theory. The root of the difficulty, I believe, bears upon the answers to fundamental questions concerning the nature of cognitive agents and the purposes which their use of language is designed to further. If this is the case, one might expect to find some of the trouble surfacing at precisely those points where the language is used to convey information about the cognitive activities associated with the use of language by such agents. So it is. The central problem of this essay is the interpretation of referential expressions in statements involving propositional attitudes, with the focus on belief contexts. But I shall begin by placing the discussion within a broader theoretical framework. This will be done by way of discussing some other puzzles that may seem at first sight rather unrelated.

Reporting on the 7th International Congress of Logic, Methodology, and Philosophy of Science, first the main topics and some organisational aspects of the congress are presented; the main part of the report focuses on recent developments in Philosophical Logic (Section 5), in particular the theory of so-called generalized quantifiers as presented at the congress. In addition, some background information on logical language analysis, its possible applications and consequences is provided.

The essay outlines the character of free logic, and motivation for its construction and development. It details some technical achievements of high philosophical interest, but urges that the role of existence assumptions in logic is still not fully understood, that unresolved old problems, both technical and philosophical, abound, and presents some new problems of considerable philosophical import in free logic.

Two quite different points have, on different occasions, been meant by, or been given as the meaning of, 'Existence is not a predicate'. The points may be related, but they are different points. This would not matter unless it resulted in confusion between the two points; unfortunately confusion has occurred on at least one occasion. My aim in this note is to show that such confusion can be found in D. F. Pears' 'Is Existence a Predicate?' (reprinted in Philosophical Logic, edited by P. F. Strawson). More precisely, my claim is that Pears is led to say some very strange things because he is trying to relate to one meaning of ENP ('Existence is not a predicate') remarks that were intended to relate to the other meaning. (i) The two points. The two points which have been linked with ENP are familiar. One we find in (amongst many other sources) Russell (e.g. Introduction to Mathematical Philosophy, Chapter I5). The point can at least be identified by the following statement: 'A's exist' is not about particular members (instances, arguments) or each member (instance, argument) of the class of A's (of the concept 'A', satisfying the function 'x is an A'); rather, it is about the class of A's (the concept 'A', the function 'x is an A'). Specifically to say that A's exist is to say that the class of A's has members (the concept 'A' has instances, the function 'x is an A' has arguments that satisfy it). Let us call this point the CMP (the classmembership point). The other point we can find stated in Pears' article (on p. 98). In the statement 'This room exists' the subject-phrase 'This room' implies that this room exists by making a reference to it, and thus the verb 'exists' is redundant. And in the statement 'This room does not exist' the verb contradicts what is implied by the subject-phrase. Pears describes the point in terms of 'referential tautologies' and 'referential contradictions' (let us call it the RTCP) and extends it (p. ioi) to cover general existential statements. Now, about the RTCP Pears says two particular things which I want to examine. He says that the RTCP is a refinement of two 'inexact formulations' of ENP; and he says that in his exposition of the RTCP, he is following up some ideas that G. E. Moore put forward in his article 'Is Existence a Predicate?' (Proceedings of the Aristotelian Society, Supp. Vol., I936. Reprinted in Logic and Language, Series II, edited by A. G. N. Flew.) (ii) The first inexact formulation (IFi). 'If I assert that tigers exist, the verb "exist" does not add anything to the concept of the subject "tigers" (P. 97). How does Pears show that the RTCP is 'really a refinement' of IFi? The connection is made through the idea of adding. In that the verb

J-P. SARTRE HAS WRITTEN AT LENGTH ON THE QUESTION OF HOW THE myth of the French revolution is possible. The intelligibility, let alone the truth, of his answer need not detain us unduly. But the question is a good one. The past two centuries or so have indeed been the age of myth of the Revolution. As in philosophical logic, the definite article has distinctive and powerful implications and gives rise to very interesting problems. In this case, they are not merely logical, but also, and above all, moral, epistemic and political. The definite article seems to imply existence; and it also seems to imply uniqueness. Even more disturbingly, it seems to suggest, in this case, moral rightness and political authority. The Revolution is necessary, unique and inevitable, legitimate and authoritative. But to claim these traits, it must also be identifiable; and it can only be identified, hailed and revered, if it carries some manifest stigmata. But what are they? Can they not be counterfeited? Are there not peddlers of fake stigmata, or, worse still, of false theories concerning what constitutes the stigmata?

The patterns of human reasoning have been a matter of debate in the field of anthropology for almost its entire history, but little of the discussion has been translated into empirical study. The syllogism offers a good opportunity to study universal and particular aspects of human logic because its logic is well known, and folk taxonomies are found in all human languages. In this study the syllogism as explicated in philosophical logic was used as the methodological basis for the study of categorical reasoning in four languages--Mende, Ojibwa, English, and Navajo. All four languages displayed amazing consistency in syllogistic reasoning, accounted for in terms of taxonomic semantics.

In this article I should like briefly to ground two mutually determining propositions: 1. The philosophical logic that has emerged in the twentieth century and that corresponds to contemporary culture is a logic of paradox.

Because thought processes underlie all human action and can distinguish one culture from another, the social sciences must face the problem of determining how people think. Reasoning can be viewed as abstract and not connected to any particular human activity, as it is in philosophical logic, or it can be seen as a process in a particular linguistic, social and cultural setting, as it is in ethno-logic. Recently anthropologists, developmental psychologists and other scholars working under the general rubric of cognitive science have studied issues in ethno-logic but these studies are flawed because the researchers accepted philosophical logic as the norm under which they judged the actions of their subjects. Good theory in ethno-logic can only come from study which describes thought processes from the natives point of view. One such theory states that conclusions are logically established on the semantic structure of the argument. This theory accounts for both universal and culture specific aspects of reasoning, is testable, opens new areas of research and provides researchers with a firmly grounded method for using meaning to account for behavior.

It is my contention that the profundity of Wittgenstein’s discussion of the problem of following a rule has not yet been fully appreciated in our philosophical environment. This is, to say the least, rather surprising, given its multitudinous connections with many other philosophical problems of the first order, especially, in the philosophy of mathematics, the philosophy of mind and philosophical logic. Saul Kripke’s latest contribution to philosophy has been a book whose title, Wittgenstein: On Rules and Private Language, deals precisely with these issues. Kripke’s discussion, brilliant and lucid as it was to be expected from the author of Naming and Necessity, has exerted an amazing influence on analytical philosophers dealing with problems as diverse as realism in semantics, the notion of ‘proof’ in mathematics, the possibility of a private language, the theory of meaning for a natural language, behaviourism in the philosophy of mind, the notion of objectivity, and many others. Notwithstanding the immense amount of resources which Kripke brought to hear in his discussion, I believe that if we follow him all the way, we end up with a feeling that the point we have reached is very different from the one Wittgenstein wanted and, indeed, argued for. If, then, my reading of Wittgenstein’s texts is on anything like the right lines, one should be a bit skeptical about Kripke’s exegesis. Two years after the publication of Kripke’s book, John McDowell wrote a splendid essay entitled ‘Wittgenstein on Following a Rule’ in which he challenges Kripke’s interpretation and, to my mind, some of McDowell’s arguments prove to be devastating of the position endorsed by Kripke. But McDowell considers it to be absolutely essential, for his own arguments to go through, to assume what I call ‘the community view’ on the practice of following a rule and this, I think, is a mistake. In a recent book, Colin McGinn has endorsed this conclusion, and I’ve tried to make it more appealing by exploring the possibility of bringing into play a causal theory of understanding.

The discussion of the semantics of inconsistent truth theories now comes to a pause. The preceding is of course but a sketch; many interesting questions remain to be answered. The second part of this essay, however, will not seek to answer them. Rather, I will turn to the discussion of the proof theory of truth theory: the local and global logic of truth.

The concept of truth is a fundamental category in the theory of knowledge and philosophy in general. Other philosophical categories (matter, being, human existence, etc.) presuppose the concept of truth as their content or as the goal of investigatory inquiry. Philosophy begins historically with rejection of any form of opinion in the name of truth and with the counterposing of what truly exists to the variety of appearance. Thus was born theoretical thought, for which in antiquity philosophy was a synonym.

Philosophical perspectives, although eminently relevant to clinical investigation and practice, are rarely brought to bear on psychiatric topics. The author attempts to raise professional consciousness of core issues in the philosophy of science by examining the status of truth, theory, and observation in psychiatry. He evaluates prominent approaches to the problem of knowledge, particularly those of the "subjectivists" and "relativists," such as Schafer and Spence, and the "empiricists" and "inductivists," such as the proponents of DSM-III. Drawing on contemporary philosophy of science, the work of William James, and the classical Greek conviction that more truth resides in the middle than at either extreme, the author mediates between these rival points of view.

Why and how is intensional logic important for philosophy? An adequate answer to this question would require a book. I will here consider some related problems which we must solve before we can begin to understand what is involved in any such answer. They are (i) What is intensional logic ? and (ii) What is the relation between intensional logic and the extensional logics with which most of us are so much more familiar. I will dwell on a particular aspect of the second problem in some detail. The only coherent formulations of the semantics for intensional logic which-to my knowledge at least-are available at the present time take the form of extensional theories which compensate for the lack of intensionality of their underlying logic by referring explicitly to possible worlds. This raises two further questions: (i) Can such a semantic theory ever be adequate? and (ii) Would this mean that intensional logic is reducible without remainder to extensional logic. There will be no room to discuss the last of these two. But I will have a number of things to say about the first.

Interest in the history of philosophy shows no sign of diminishing. This article covers i6 books published between I972 and early 1974, and these are only a selection from the work in this field during the period. That philosophers should show an interest in the history of their subject is not surprising. Collingwood argued that the historian does not merely record, he re-thinks. Whatever the truth of this as an account of history in general, it is certainly true of the history of philosophy, and it is this that makes the subject more than a rummage through rooms full of old lumber. This rethinking of past thought, it should be stressed, does not involve the performance of some mysterious act of mental intuition. Rather, it involves asking such questions as, 'What issues were important to this man, and what bearing do they have on his philosophy? Are we, for example, to see Spinoza as someone mulling over old rabbinical texts, or are we to see him in the context of the new science of the seventeenth century?' The answer that is given will depend on which interpretation gives the better sense. Or again, we may ask 'When a philosopher appears to argue that one proposition follows from another-say, that the truth of all clear and distinct ideas follows from the perfection of God-does it in fact follow? If not, is it certain that we have grasped the logic of the argument?' Nor is this re-thinking something that can be done once and for all. We need to return to the classics of philosophy again and again, as our own views about philosophy change. For example, we see more in Leibniz than scholars did a hundred years ago, not just because we know more about Leibniz (though we do), but also because advances in philosophical logic have provided us with a new set of questions with which to approach Leibniz. It must be admitted that not all historians of philosophy re-think the past; the 'scissors and paste' historian, as Collingwood called him, is still with us. But it can be said that the historian of philosophy must re-think the past if his subject is to come alive, if the subject is not to be (in Hegel's phrase) a battlefield full of corpses. Happily, few of the books discussed below fail to bring their subject alive.

In the "Discussion" column of Teaching and Research, 1957, Nos. 1-5, Comrade Wang Fang-ming (under the pen name of Ch'iu Shih [Search for Truth]) successively contributed five articles: "Concerning 'Preliminary Laws and Forms of Correct Thought,'" "On the State of Relative Stability and Qualitative Specificity of Objective Entities," and others. In these articles he discusses a series of problems on formal logic and makes some critical comments on some popular current views in studies of logic. In the No. 6 issue of the same journal, Comrade Wang also has a paper, "On Classical Formal Logic and Inductive Logic," in which he systematically and positively presents what he had offered in the previous papers. While we believe that all these papers present some beneficial points (for example, regarding problems of the relations between formal logic and philosophy and between formal logic and inductive logic), at the same time we think that they contain quite a few mistakes and even include poisonous elements o...

Questions of dialectical logic are currently of great importance in Marxist-Leninist philosophy. However, most of the logicians in our country are working on problems of mathematical logic, which is not a philosophical science. The axiomatic method is basic to mathematical logic, and its basic concept is the notion of functional dependence. Logic, as a philosophical discipline, has always studied and should study the relationship between antecedent and consequent, which is concerned not with functional dependence, not with an external connection, but with an internal logical necessity. To reduce the logical relationship to functional dependence means to abolish the discipline of logic. No philosophical system, no philosophical work, has been, nor could be, constructed on the basis of mathematical logic.