We describe a general logical framework, Justification Logic, for reasoning about epistemic justification. Justification Logic is based on classical propositional logic augmented by justification assertions t: F that read t is a justification for F. Justification Logic absorbs basic principles originating from both mainstream epistemology and the mathematical theory of proofs. It contributes to the studies of the well-known Justified True Belief vs. Knowledge problem. We state a general Correspondence Theorem (...) showing that behind each epistemic modal logic, there is a robust system of justifications. This renders a new, evidence-based foundation for epistemic logic. As a case study, we offer a resolution of the GoldmanRed Barns in Justification Logic. Furthermore, we formalize the well-known Gettier example and reveal hidden assumptions and redundancies in Gettier’s reasoning. (shrink)

In the present paper we propose a system of propositional logic for reasoning about justification, truthmaking, and the connection between justifiers and truthmakers. The logic of justification and truthmaking is developed according to the fundamental ideas introduced by Artemov. Justifiers and truthmakers are treated in a similar way, exploiting the intuition that justifiers provide epistemic grounds for propositions to be considered true, while truthmakers provide ontological grounds for propositions to be true. This system of logic (...) is then applied both for interpreting the notorious definition of knowledge as justified true belief and for advancing a new solution to Gettier counterexamples to this standard definition. (shrink)

The paper relates evidence and justification logics, both philosophically and technically. On the philosophical side, it is suggested that the difference between the approaches to evidence in the two families of logics can be explained as a result of their focusing on two different notions of support provided by evidence. On the technical side, a justification logic with operators pertaining to both kinds of support is shown to be sound and complete with respect to a special class (...) of awareness models. In addition, a realization theorem with respect to K is shown to hold for the logic. (shrink)

Rosenkranz has recently proposed a logic for propositional, non-factive, all-things-considered justification, which is based on a logic for the notion of being in a position to know, 309–338 2018). Starting from three quite weak assumptions in addition to some of the core principles that are already accepted by Rosenkranz, I prove that, if one has positive introspective and modally robust knowledge of the axioms of minimal arithmetic, then one is in a position to know that a sentence (...) is not provable in minimal arithmetic or that the negation of that sentence is not provable in minimal arithmetic. This serves as the formal background for an example that calls into question the correctness of Rosenkranz’s logic of justification. (shrink)

What really makes the concepts of obligation or permission so important for practical philosophy? What if we could find a better concept, one that, despite the simplicity, could show itself as intuitive and rich as possible? Could justifications be used in common language and practice as a sign of ethical judgment and as a strong motive for action? In most scenarios, for example, it really doesn’t matter if a given action is obliged, permitted or forbidden, one may perform the action (...) as long as a justification for doing it is present. In this sense, the notion of justification seems to be more basic and powerful than other concepts used in the philosophical discourse. The existence of formal systems based on the epistemological side of justification, created by Artemov, led us primarily to think that justification could make the formal discourse much more accurate for ethics than the ones using deontological concepts. In the semantical and syntactical aspects, almost all of Artemov’s systems directly proved to be fruitful for ethical purposes. We also developed combinations between the standard deontic logic and logics of justification, resulting in what whe called the Logics of Normative Justification. These systems were able to change the object of the justification formulas and shed some light in ethics as a whole, normative and metaethics. Metaethics were a forgotten subject in formal ethics. We were also able to deal with some known problems in deontic logic, like the famous Ross’s paradox and the expressiveness of prima facie and all-things-considered obligations. (shrink)

Theories of epistemic justification are commonly assessed by exploring their predictions about particular hypothetical cases – predictions as to whether justification is present or absent in this or that case. With a few exceptions, it is much less common for theories of epistemic justification to be assessed by exploring their predictions about logical principles. The exceptions are a handful of ‘closure’ principles, which have received a lot of attention, and which certain theories of justification are well (...) known to invalidate. But these closure principles are only a small sample of the logical principles that we might consider. In this paper, I will outline four further logical principles that plausibly hold for justification and two which plausibly do not. While my primary aim is just to put these principles forward, I will use them to evaluate some different approaches to justification and (tentatively) conclude that a ‘normic’ theory of justification best captures its logic. (shrink)

In the above pages I have sketched a history of the genesis and comparative evaluation of the repressor model of genetic regulation of enzyme induction. I have not attempted in this article to carry out an analysis of the more scientifically interesting fully developed Jacob-Monod operon theory of genetic regulations but such an analysis of the operon theory would not, I believe, involve any additional logical or epistemological features than have been discussed above. I have argued that the above account (...) of the development of a theory of enzyme induction involved inferential moves and well-characterized desiderata, of both empirical and non-empirical character, in the genesis and evaluation of new hypotheses and theories. I have also contended that the reasoning displayed in the genesis of a theory is in a large measure identical to that utilized in evaluating a theory. Both of these conclusions are at variance with the views of philosophers such as H. Reichenbach, Sir Karl Popper, and C.G. Hempel who have argued that the genesis of new hypotheses is primarily an irrational affair and that only the context of justification is susceptible of rational reconstruction. In the alternative view presented here, scientific discovery and scientific justification represent the application in contexts, which are primarily telically distinguishable, of a fundamentally unitary logic of scientific inquiry. (shrink)

Justification Logic provides an axiomatic description of justifications and delegates the question of their nature to semantics. In this note, we address the conceptual issue of the logical type of justifications: we argue that justifications in the logical setting are naturally interpreted as sets of formulas which leads to a class of epistemic models that we call modular models . We show that Fitting models for Justification Logic naturally encode modular models and can be regarded as (...) convenient pre-models of the former. (shrink)

Rosenkranz (2021) devised two bimodal epistemic logics: an idealized one and a realistic one. The former is shown to be sound with respect to a class of neighborhood frames called i-frames. Rosenkranz designed a specific i-frame able to invalidate a series of undesired formulas, proving that these are not theorems of the idealized logic. Nonetheless, an unwanted formula and an unwanted rule of inference are not invalidated. Invalidating the former guarantees the distinction between the two modal operators characteristic of (...) the logic, while invalidating the latter is crucial in order to deal with the problem of logical omniscience. In this paper, I present an i-frame able to invalidate all the undesired formulas already invalidated by Rosenkranz, together with the missing formula and rule of inference. (shrink)

In Artemovʼs Justification Logic, one can make statements interpreted as “t is evidence for the truth of formula F.” We propose a variant of this logic in which one can say “I have degree r of confidence that t is evidence for the truth of formula F.” After defining both an axiomatic approach and a semantics for this Logic of Uncertain Justifications, we will prove the usual soundness and completeness theorems.

In the 1980s, Pollock’s work on default reasons started the quest in the AI community for a formal system of defeasible argumentation. The main goal of this paper is to provide a logic of structured defeasible arguments using the language of justification logic. In this logic, we introduce defeasible justification assertions of the type t : F that read as “t is a defeasible reason that justifies F”. Such formulas are then interpreted as arguments and (...) their acceptance semantics is given in analogy to Dung’s abstract argumentation framework semantics. We show that a large subclass of Dung’s frameworks that we call “warranted” frameworks is a special case of our logic in the sense that Dung’s frameworks can be obtained from justification logic-based theories by focusing on a single aspect of attacks among justification logic arguments and Dung’s warranted frameworks always have multiple justification logic instantiations called “realizations”. We first define a new justification logic that relies on operational semantics for default logic. One of the key features that is absent in standard justification logics is the possibility to weigh different epistemic reasons or pieces of evidence that might conflict with one another. To amend this, we develop a semantics for “defeaters”: conflicting reasons forming a basis to doubt the original conclusion or to believe an opposite statement. This enables us to formalize non-monotonic justifications that prompt extension revision already for normal default theories. Then we present our logic as a system for abstract argumentation with structured arguments. The format of conflicting reasons overlaps with the idea of attacks between arguments to the extent that it is possible to define all the standard notions of argumentation framework extensions. Using the definitions of extensions, we establish formal correspondence between Dung’s original argumentation semantics and our operational semantics for default theories. One of the results shows that the notorious attack cycles from abstract argumentation cannot always be realized as justification logic default theories. (shrink)

Several justification logics have been created, starting with the logic LP, [1]. These can be thought of as explicit versions of modal logics, or of logics of knowledge or belief, in which the unanalyzed necessity (knowledge, belief) operator has been replaced with a family of explicit justification terms. We begin by sketching the basics of justification logics and their relations with modal logics. Then we move to new material. Modal logics come in various strengths. For their (...) corresponding justification logics, differing strength is reflected in different vocabularies. What we show here is that for justification logics corresponding to modal logics extending T, various familiar extensions are actually conservative with respect to each other. Our method of proof is very simple, and general enough to handle several justification logics not directly corresponding to distinct modal logics. Our methods do not, however, allow us to prove comparable results for justification logics corresponding to modal logics that do not extend T. That is, we are able to handle explicit logics of knowledge, but not explicit logics of belief. This remains open. (shrink)

The standard use of the propositional calculus ('P.C.?) in analyzing the validity of inferences involving conditionals leads to fallacies, and the problem is to determine where P.C. may be ?safely? used. An alternative analysis of criteria of reasonableness of inferences in terms of conditions of justification rather than truth of statements is proposed. It is argued, under certain restrictions, that P. C. may be safely used, except in inferences whose conclusions are conditionals whose antecedents are incompatible with the premises (...) in the sense that if the antecedent became known, some of the previously asserted premises would have to be withdrawn. (shrink)

In this paper we consider logical inference as an activity that results in proofs and hence produces knowledge. We suggest to merge the semantical analysis of deliberatively seeing-to-it-that from stit theory and the semantics of the epistemic logic with justification from. The general idea is to understand proving that A as seeing to it that a proof of A is available. We introduce a semantics of various notions of proving as an activity and present a number of valid (...) principles that relate the various notions of proving to each other and to notions of justified knowledge, implicit knowledge, and possibility. We also point out and comment upon certain principles our semantics fails to validate. (shrink)

Robert Stern investigates how scepticism can be countered by using transcendental arguments concerning the necessary conditions for the possibility of experience, language, or thought. He shows that the most damaging sceptical questions concern neither the certainty of our beliefs nor the reliability of our belief-forming methods, but rather how we can justify our beliefs.

The purpose of this paper is to present a formalization of the language, semantics and axiomatization of justification logic in Coq. We present proofs in a natural deduction style derived from the axiomatic approach of justification logic. Additionally, we present possible world semantics in Coq based on Fitting models to formalize the semantic satisfaction of formulas. As an important result, with this implementation, it is possible to give a proof of soundness for $\mathsf{L}\mathsf{P}$ with respect to (...) Fitting models. (shrink)

In the classical account of knowledge, S knows that P if and only if S believes that P, S is justified in believing that P, and P is true (JTB).. In 1963, Gettier presented two problems that casted doubt on this account. Since then, numerous authors proposed modifications or clarifications of JTB, however, these efforts have not produced a satis-factory solution. In this paper, the focus is on logical properties of justification. The Get-tier problem Case II is expressed in (...) sentential logic and Gettier Minimal Assumption (GMA) is introduced. It is shown that Gettier must have used GMA or some other as-sumption that entails GMA in his construction of Case II. Rejection of GMA solves Get-tier problem Case II and it is a step towards a better understanding of the logical proper-ties of justification and knowledge. (shrink)

A prominent issue in mainstream epistemology is the controversy about doxastic obligations and doxastic voluntarism. In the present paper it is argued that this discussion can benefit from forging links with formal epistemology, namely the combined modal logic of belief, agency, and obligation. A stit-theory-based semantics for deontic doxastic logic is suggested, and it is claimed that this is helpful and illuminating in dealing with the mentioned intricate and important problems from mainstream epistemology. Moreover, it is argued that (...) this linking is of mutual benefit. The discussion of doxastic voluntarism directs the attention of doxastic logicians to the notion of belief formation and thus to dynamic aspects of beliefs that have hitherto been neglected. The development of a formal language and semantics for ascriptions of belief formation may contribute to clarifying the contents and the implications of voluntaristic claims. A simple observation concerning other-agent nestings of stit-operators, for instance, may help illuminating the notions of making belief and responsibility for beliefs of others. In this way, stit-theory may serve as a bridge between mainstream and formal epistemology. (shrink)

Three decades ago Laudan posed the challenge: Why should the logic of discovery be revived? This paper tries to answer this question arguing that the logic of discovery should be revived, on the one hand, because, by Gödel’s second incompleteness theorem, mathematical logic fails to be the logic of justification, and only reviving the logic of discovery logic may continue to have an important role. On the other hand, scientists use heuristic tools in (...) their work, and it may be useful to study such tools systematically in order to improve current heuristic tools or to develop new ones. As a step towards reviving the logic of discovery, the paper follows Aristotle in asserting that logic must be a tool for the method of science, and outlines an approach to the logic of discovery based on the analytic method and on ampliative inference rules. (shrink)

This book provides a new philosophical, semantical and historical analysis of and justification for the relevant logic of entailment. Its fresh and original perspective on the logic of entailment will be valuable for all who want to know more about the historical and philosophical origins of modern symbolic logic.

This book revives inductive logic by bringing out the underlying epistemology. The resulting structural reliabilist theory propounds the view that justification supervenes on syntactic and semantic properties of sentences as justification-bearers. It is claimed to set up a genuine alternative to the prevailing theories of justification. Kawalec substantiates this claim by confronting structural reliabilism with a number of epistemological problems. While the book is addressed to both professionals and students of philosophical logic, probability, epistemology, and (...) philosophy of science, it also surveys ideas central to the development of philosophy in the 20th century. It will be a valuable companion to multifarious graduate and postgraduate courses. (shrink)

Kevin T. Kelly and Clark Glymour. Why Bayesian Confirmation Does Not Capture the Logic of Scientific Justification.

The paper explores a structural account of propositional justification in terms of the notion of being in a position to know and negation. Combined with a non-normal logic for being in a position to know, the account allows for the derivation of plausible principles of justification. The account is neutral on whether justification is grounded in internally individuated mental states, and likewise on whether it is grounded in facts that are already accessible by introspection or reflection (...) alone. To this extent, it is compatible both with internalism and with externalism about justification. Even so, the account allows for the proof of principles that are commonly conceived to depend on an internalist conception of justification. The account likewise coheres both with epistemic contextualism and with its rejection, and is compatible both with the knowledge-first approach and with its rejection. Despite its neutrality on these issues, the account makes propositional justification luminous and so is controversial. However, it proves quite resilient in the light of recent anti-luminosity arguments. (shrink)

Justification Logic is a family of epistemic logical systems obtained from modal logics of knowledge by adding a new type of formula t:F, which is read t is a justification for F. The principal epistemic modal logic S4 includes Tarski’s well-known topological interpretation, according to which the modality 2X is read the Interior of X in a topological space (the topological equivalent of the ‘knowable part of X’). In this paper, we extend Tarski’s topological interpretation from (...) S4 to Justification Logic systems with both modality and justification assertions. The topological semantics interprets t:X as a reachable subset of X (the topological equivalent of ‘test t confirms X’). We establish a number of soundness and completeness results with respect to Kripke topology and the real topology for S4-based systems of Justification Logic. (shrink)

We present a complete, decidable logic for reasoning about a notion of completely trustworthy evidence and its relations to justifiable belief and knowledge, as well as to their explicit justifications. This logic makes use of a number of evidence-related notions such as availability, admissibility, and “goodness” of a piece of evidence, and is based on an innovative modification of the Fitting semantics for Artemovʼs Justification Logic designed to preempt Gettier-type counterexamples. We combine this with ideas from (...) belief revision and awareness logics to provide an account for explicitly justified knowledge based on conclusive evidence that addresses the problem of omniscience. (shrink)

The relationship between discovery and justification is not clear. According to a standard twentieth-century opinion, in the philosophy of science these two are understood as separate problems: how to recognize and conceptualize the object of study and how to find the justification for the conceptualized belief. How to study the logic of discovery? What kind of logic might such a logic be? The basic observation is that discoveries do not take place in a vacuum. They (...) have to be localized into scientific inquiry processes: a discovery is a discovery only in the context of a scientific inquiry process. To do this we use a systematic logico-philosophical model called the interrogative model of inquiry, which was developed by Jaakko Hintikka. The interrogative model of inquiry allows us to consider the scientific inquiry process as a strategic, goal-tracking process which gives justification for the discovery. The model allows us to formulate a systematic logic of scientific discovery and justification. (shrink)

In the contemporary philosophy of set theory, discussion of new axioms that purport to resolve independence necessitates an explanation of how they come to be justified. Ordinarily, justification is divided into two broad kinds: intrinsic justification relates to how `intuitively plausible' an axiom is, whereas extrinsic justification supports an axiom by identifying certain `desirable' consequences. This paper puts pressure on how this distinction is formulated and construed. In particular, we argue that the distinction as often presented is (...) neither well-demarcated nor sufficiently precise. Instead, we suggest that the process of justification in set theory should not be thought of as neatly divisible in this way, but should rather be understood as a conceptually indivisible notion linked to the goal of explanation. (shrink)

When we say “I know why he was late”, we know not only the fact that he was late, but also an explanation of this fact. We propose a logical framework of “knowing why” inspired by the existing formal studies on why-questions, scientific explanation, and justification logic. We introduce the Kyi\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\mathcal {K}}{}\textit{y}}_i$$\end{document} operator into the language of epistemic logic to express “agent i knows why φ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} (...) \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varphi $$\end{document}” and propose a Kripke-style semantics of such expressions in terms of knowing an explanation of φ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varphi $$\end{document}. We obtain two sound and complete axiomatizations w.r.t. two different model classes depending on different assumptions about introspection. Finally we connect our logic with justification logic technically by providing an alternative semantics and an in-depth comparison on various design choices. (shrink)

The first two sections of this paper jointly comprise an edited version of the commentary I presented in the panel discussion of Harald R. Wohlrapp, The concept of argument: A philosophical foundation at the OSSA 11 conference, May 2016. My principal focus was on a claim Wohlrapp makes about the extent to which his concept of justification is "reconcilable" with the views of current philosophers about justifications. Following the conference, Wohlrapp sent me a response to my commentary. In section (...) 3, I report and reply to three of the comments he made in his response. (shrink)

My project in the dissertation is to develop a constructivist account of the normative structure of political or civil obligations. The first part of the dissertation focuses on Kant's moral and political constructivism respectively. In chapter two I argue that Kant's account of the normativity of moral obligations is rooted in the idea of moral community which is an objective end that is built into the structure of our practical reasoning. Moral obligations are justified for Kant because they reflect our (...) rational agency and, in particular, the interest we have in promoting a moral community. ;In chapter three I focus on what Kant's idea of the problem of politics: the construction of a society that can successfully and universally administer justice while promoting the interest each citizen has in living in realizing their full capacities as autonomous human beings. I argue that Kant is unable to show that civil obligation---the duties we have qua citizens---are normative in the right sort of way. Kant's account of civil or juridical obligations fails to show that these obligations are normative as moral laws---that they are justified and reason-giving in virtue of their connection to our political consciousness. ;In chapters four through six I present a fully developed account of how political constructivism uses the features of practical reason to evaluate and assemble our ordinary political consciousness---fundamental ideas of free and open society---into a conception of justice, and the normativity of civil obligations---how they are justified and in what sense they are reason-giving for persons qua citizens. ;I lay out Rawls's argument that justice as fairness is a freestanding view by working out exactly how the view is put together without appeal to any particular comprehensive doctrine. After setting out the mechanics, if you will, of political constructivism, I then present an account of the normativity of the political conception: the justification of principles of justice and the prescriptivity or reason-giving force of principles of justice. (shrink)

The aim of this paper is to provide an intuitive semantics for systems of justification logic which allows us to cope with the distinction between implicit and explicit justifiers. The paper is subdivided into three sections. In the first one, the distinction between implicit and explicit justifiers is presented and connected with a proof-theoretic distinction between two ways of interpreting sequences of sentences; that is, as sequences of axioms in a certain set and as sequences proofs constructed from (...) that set of axioms. In the second section, a basic system of justification logic for implicit and explicit justifiers is analyzed and some significant facts about it are proved. In the final section, an adequate semantics is proposed, and the system is proved to be sound and complete whit respect to it. (shrink)

Almost all contemporary philosophers on the subject agree that emotions play an indispensable role in the justification (as opposed to the mere causation) of other mental states and actions. However, how this role is to be understood is still an open question. At the core of the debate is the phenomenon of conflict without contradiction: why is it that an emotion need not be revised in the light of better judgment and knowledge? Conflict without contradiction has been explained either (...) by difference in content between emotion and judgment, or by a difference in the respective attitude towards content. I argue that conflict without contradiction is due to both differences, where difference in content is prior to difference in attitude. (shrink)

Take a correct sequent of formal logic, perhaps a simple logical truth, like the law of excluded middle, or something with premises, like disjunctive syllogism, but basically a claim of the form \.Γ can be empty. If you don’t like my examples, feel free to choose your own, everything I have to say should apply to those as well. Such a sequent attributes the properties of logical truth or logical consequence to a schematic sentence or argument. This paper aims (...) to answer the question of how beliefs in such attributions are justified, on both its descriptive and normative interpretations; I aim to say when we generally take ourselves to be justified in forming such beliefs, and to make it plausible that beliefs formed this way really are justified.We can ask such questions about many domains but there are special difficulties for answering them in logic. Some of the difficulties stem from the fact that logic is thought t.. (shrink)

Despite the tendency to think that the justification of revealed truths depends on a verifiable contact with divine reality, this essay argues that the authoritative status of revelations is due to their role in defining a distinctively religious order of judgment. Rather than being immediately apparent to everyone, this kind of authority is local to particular forms of judgment that depend on the principles that frame these ways of thinking. Revelatory claims are logically exempted from the normal demands of (...) justification because of this role they have as definitive judgments, and they share their immunity from ordinary forms of justification with other axiomatic principles. Yet their authority can in certain cases be challenged, and it is a secondary purpose of this essay to bring the various ways of challenging their truth to light. (shrink)

Several justification logics have evolved, starting with the logicLP, (Artemov 2001). These can be thought of as explicit versions of modal logics, or logics of knowledge or belief, in which the unanalyzed necessity (knowledge, belief) operator has been replaced with a family of explicit justification terms. Modal logics come in various strengths. For their corresponding justification logics, differing strength is reflected in different vocabularies. What we show here is that for justification logics corresponding to modal logics (...) extending T, various familiar extensions are actually conservative with respect to each other. Our method of proof is very simple, and general enough to handle several justification logics not directly corresponding to distinct modal logics. Our methods do not, however, allow us to prove comparable results for justification logics corresponding to modal logics that do not extend T. That is, we are able to handle explicit logics of knowledge, but not explicit logics of belief. This remains open. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:HUME ON THE LOGIC OF DESIGN (i) Respectable Inductive Thinking Readers seeking to understand Hume's views concerning inductive reasoning often turn just to the obviously relevant sections of the Treatise and the 2 first Enquiry. In this paper I want to suggest that a broader approach is desirable, and specifically that the Dialogues Concerning Natural Religion shed additional significant light on Hume's views about induction. In those well (...) known passages of the Treatise and the first Enquiry Hume presents his critique of the idea of necessary connection; central to this critique is his point that thinking which goes beyond its premises in order to arrive at non-trivial factual conclusions cannot be demonstrative reasoning. Does this lead Hume into a radical scepticism concerning factual knowledge? A majority of interpreters do regard him as holding that because this kind of thinking is not demonstrative reasoning it cannot have any justification for the conclusions it reaches. In this connection, Hume is said to be committed to "deductivism" — the assumption that only demonstrative (deductive) reasoning can succeed in justifying conclusions. Interpreted in this way, Hume holds that demonstrative reasoning cannot establish non-trivial factual conclusions and that non-demonstrative thinking cannot establish them either; Hume is therefore committed to the view that non-trivial factual claims cannot be established, and so cannot be known. Thus, Hume is a radical sceptic who denies that we can attain any knowledge of non-trivial factual conclusions. Of course Hume does not stop with this negative result, but proceeds to affirm that our human nature impels us to derive conclusions about matters of fact even when it is not rational to do so. This occurs in accordance with the innate propensity by which the imagination operates, so that we cannot help but 2. engage in a specific style of non-rational thinking about these matters. This style may be characterized roughly as that of expecting to have future experiences which resemble our past experiences. This way of interpreting Hume which I have just sketched has been quite widely accepted, and I think it represents the way of understanding Hume which most readers are likely to arrive at if they simply read those well known passages of the Treatise and first Enquiry. It does seem to me to be essentially correct as a reading of those passages. To be sure, this interpretation has been challenged by several writers, and recently it has been denounced with especial vigor by Beauchamp and 4 Rosenberg in their stimulating book. Beauchamp and Rosenberg maintain that nowhere in the Treatise or Enquiry does Hume voice any general scepticism about the drawing of conclusions concerning matters of fact. On their reading, Hume is merely rejecting the view that factual conclusions can be proved demonstratively; he is not at all suggesting that the drawing of such conclusions is in general unjustified. They see him as a staunch and consistent advocate of inductive reasoning. I shall not take time here to try to thresh out the complex details of this controversy. For present purposes I shall merely indicate where I stand. I believe that Beauchamp and Rosenberg have read the Treatise and the Enquiry too much in the light of what they think Hume ought to be saying in order for him to have a consistent and plausible position. I think they water down too much his acid remarks about the lack of rationality of thinking which reaches non-trivial factual conclusions, and I think they attach too little weight to the manner in which Hume aligns himself with ancient scepticism. Unlike Beauchamp and Rosenberg, I consider that Hume is not a highly consistent writer, I think he sometimes has not thought through the implications of what he says in one place so 3. as to reconcile it with what he says in some other places. (To say this is not to denigrate the value of his work; much of the excitement of his thought stems from his willingness to press his opinions to inconsistent extremes.) Therefore, I think it best in reading Hume to be alert for possibly conflicting lines of thought which are present in the texts and which should not be... (shrink)

It is noted that Popper separates the creation of concepts, conjectures, hypotheses and theories—the context of invention—from the testing thereof—the context of justification—arguing that only the latter is susceptible of rigorous logical analysis. Efforts on the part of others to shift or eradicate the demarcation established by this distinction are discussed and the relationship of these considerations to the claims of “strong artificial intelligence” is pointed out. It is argued that the mode of education of scientists, as well as (...) reports of celebrated scientists, support Popper's judgement in this matter. An historical episode from Faraday's later career is used to illustrate the historiographical strength of Lakatos' “methodology of research programs.”. (shrink)