Why Single Premise Closure Might Fail
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Logic, Reasoning, and Revision
Logic, Reasoning, and Revision Abstract The traditional connection between logic and reasoning has been under pressure ever since Gilbert Harman attacked the received view that logic yields norms for what we should believe. In this paper I first place Harman’s challenge in the broader context of the dialectic between logical revisionists like Bob Meyer and sceptics about the role of logic in reasoning like Harman. I then develop a formal model based on contemporary epistemic and doxastic logic in which the relation between logic and norms for belief can be captured. introduction The canons of classical deductive logic provide, at least according to a widespread but presumably naive view, general as well as infallible norms for reasoning. Obviously, few instances of actual reasoning have such prop- erties, and it is therefore not surprising that the naive view has been chal- lenged in many ways. Four kinds of challenges are relevant to the question of where the naive view goes wrong, but each of these challenges is also in- teresting because it allows us to focus on a particular aspect of the relation between deductive logic, reasoning, and logical revision. Challenges to the naive view that classical deductive logic directly yields norms for reason- ing come in two sorts. Two of them are straightforwardly revisionist; they claim that the consequence relation of classical logic is the culprit. The remaining two directly question the naive view about the normative role of logic for reasoning; they do not think that the philosophical notion of en- tailment (however conceived) is as relevant to reasoning as has traditionally been assumed. -
Mathematical Logic
Proof Theory. Mathematical Logic. From the XIXth century to the 1960s, logic was essentially mathematical. Development of first-order logic (1879-1928): Frege, Hilbert, Bernays, Ackermann. Development of the fundamental axiom systems for mathematics (1880s-1920s): Cantor, Peano, Zermelo, Fraenkel, Skolem, von Neumann. Giuseppe Peano (1858-1932) Core Logic – 2005/06-1ab – p. 2/43 Mathematical Logic. From the XIXth century to the 1960s, logic was essentially mathematical. Development of first-order logic (1879-1928): Frege, Hilbert, Bernays, Ackermann. Development of the fundamental axiom systems for mathematics (1880s-1920s): Cantor, Peano, Zermelo, Fraenkel, Skolem, von Neumann. Traditional four areas of mathematical logic: Proof Theory. Recursion Theory. Model Theory. Set Theory. Core Logic – 2005/06-1ab – p. 2/43 Gödel (1). Kurt Gödel (1906-1978) Studied at the University of Vienna; PhD supervisor Hans Hahn (1879-1934). Thesis (1929): Gödel Completeness Theorem. 1931: “Über formal unentscheidbare Sätze der Principia Mathematica und verwandter Systeme I”. Gödel’s First Incompleteness Theorem and a proof sketch of the Second Incompleteness Theorem. Core Logic – 2005/06-1ab – p. 3/43 Gödel (2). 1935-1940: Gödel proves the consistency of the Axiom of Choice and the Generalized Continuum Hypothesis with the axioms of set theory (solving one half of Hilbert’s 1st Problem). 1940: Emigration to the USA: Princeton. Close friendship to Einstein, Morgenstern and von Neumann. Suffered from severe hypochondria and paranoia. Strong views on the philosophy of mathematics. Core Logic – 2005/06-1ab – p. 4/43 Gödel’s Incompleteness Theorem (1). 1928: At the ICM in Bologna, Hilbert claims that the work of Ackermann and von Neumann constitutes a proof of the consistency of arithmetic. -
In Defence of Constructive Empiricism: Metaphysics Versus Science
To appear in Journal for General Philosophy of Science (2004) In Defence of Constructive Empiricism: Metaphysics versus Science F.A. Muller Institute for the History and Philosophy of Science and Mathematics Utrecht University, P.O. Box 80.000 3508 TA Utrecht, The Netherlands E-mail: [email protected] August 2003 Summary Over the past years, in books and journals (this journal included), N. Maxwell launched a ferocious attack on B.C. van Fraassen's view of science called Con- structive Empiricism (CE). This attack has been totally ignored. Must we con- clude from this silence that no defence is possible against the attack and that a fortiori Maxwell has buried CE once and for all, or is the attack too obviously flawed as not to merit exposure? We believe that neither is the case and hope that a careful dissection of Maxwell's reasoning will make this clear. This dis- section includes an analysis of Maxwell's `aberrance-argument' (omnipresent in his many writings) for the contentious claim that science implicitly and per- manently accepts a substantial, metaphysical thesis about the universe. This claim generally has been ignored too, for more than a quarter of a century. Our con- clusions will be that, first, Maxwell's attacks on CE can be beaten off; secondly, his `aberrance-arguments' do not establish what Maxwell believes they estab- lish; but, thirdly, we can draw a number of valuable lessons from these attacks about the nature of science and of the libertarian nature of CE. Table of Contents on other side −! Contents 1 Exordium: What is Maxwell's Argument? 1 2 Does Science Implicitly Accept Metaphysics? 3 2.1 Aberrant Theories . -
In Defence of Folk Psychology
FRANK JACKSON & PHILIP PETTIT IN DEFENCE OF FOLK PSYCHOLOGY (Received 14 October, 1988) It turned out that there was no phlogiston, no caloric fluid, and no luminiferous ether. Might it turn out that there are no beliefs and desires? Patricia and Paul Churchland say yes. ~ We say no. In part one we give our positive argument for the existence of beliefs and desires, and in part two we offer a diagnosis of what has misled the Church- lands into holding that it might very well turn out that there are no beliefs and desires. 1. THE EXISTENCE OF BELIEFS AND DESIRES 1.1. Our Strategy Eliminativists do not insist that it is certain as of now that there are no beliefs and desires. They insist that it might very well turn out that there are no beliefs and desires. Thus, in order to engage with their position, we need to provide a case for beliefs and desires which, in addition to being a strong one given what we now know, is one which is peculiarly unlikely to be undermined by future progress in neuroscience. Our first step towards providing such a case is to observe that the question of the existence of beliefs and desires as conceived in folk psychology can be divided into two questions. There exist beliefs and desires if there exist creatures with states truly describable as states of believing that such-and-such or desiring that so-and-so. Our question, then, can be divided into two questions. First, what is it for a state to be truly describable as a belief or as a desire; what, that is, needs to be the case according to our folk conception of belief and desire for a state to be a belief or a desire? And, second, is what needs to be the case in fact the case? Accordingly , if we accepted a certain, simple behaviourist account of, say, our folk Philosophical Studies 59:31--54, 1990. -
Knowledge Is Closed Under Analytic Content
Knowledge is Closed Under Analytic Content Samuel Z. Elgin July 2019 Abstract I defend the claim that knowledge is closed under analytic content: that if an agent S knows that p and q is an analytic part of p, then S knows that q. After identifying the relevant notion of analyticity, I argue that this principle correctly diagnoses challenging cases and that it gives rise to novel and plausible necessary and sufficient conditions for knowledge. I close by arguing that contextualists who maintain that knowledge is closed under classical entailment within|but not between|linguistic contexts are tacitly committed to this principle's truth. Knowledge of some propositions requires knowledge of others. All those who know that p ^ q also know that p|as do those who know that p. Agents ignorant of the truth of p lack the epistemic resources to know either the conjunction or the double negation. When does this hold? Is it a feature of conjunction and negation in particular, or are they instances of a more general pattern? Why does this hold? What makes it the case that knowledge of some propositions requires knowledge of others? This is the interpretive question of epistemic closure. The most basic formulation of the closure principle is the following: Na¨ıve Closure: If an agent S knows that p and p entails q, then S knows that q.1 Na¨ıve Closure is transparently false. S may fail to realize that p entails q, and perhaps even disbelieve that q. And, surely, if S does not even believe that q, then S does not know that q. -
1 Epistemic Closure in Folk Epistemology James R. Beebe And
Epistemic Closure in Folk Epistemology* James R. Beebe and Jake Monaghan (University at Buffalo) Forthcoming in Joshua Knobe, Tania Lombrozo, and Shaun Nichols (eds.), Oxford Studies in Epistemology We report the results of four empirical studies designed to investigate the extent to which an epistemic closure principle for knowledge is reflected in folk epistemology. Previous work by Turri (2015a) suggested that our shared epistemic practices may only include a source-relative closure principle—one that applies to perceptual beliefs but not to inferential beliefs. We argue that the results of our studies provide reason for thinking that individuals are making a performance error when their knowledge attributions and denials conflict with the closure principle. When we used research materials that overcome what we think are difficulties with Turri’s original materials, we found that participants did not reject closure. Furthermore, when we presented Turri’s original materials to non- philosophers with expertise in deductive reasoning (viz., professional mathematicians), they endorsed closure for both perceptual and inferential beliefs. Our results suggest that an unrestricted closure principle—one that applies to all beliefs, regardless of their source—provides a better model of folk patterns of knowledge attribution than a source-relative closure principle. * This paper has benefited greatly from helpful comments and suggestions from John Turri, Wesley Buckwalter, two anonymous reviewers from Oxford Studies in Experimental Philosophy, an anonymous reviewer for the Second Annual Minds Online Conference, and audiences at the 2015 Experimental Philosophy Group UK conference, the 2016 Southern Society for Philosophy and Psychology conference, and University College Dublin. 1 Keywords: epistemic closure, folk epistemology, experimental philosophy, knowledge, expertise 1. -
Hereafter, Closure
Erkenntnis (2006) Ó Springer 2006 DOI 10.1007/s10670-006-9009-y PETER MURPHY A STRATEGY FOR ASSESSING CLOSURE ABSTRACT. This paper looks at an argument strategy for assessing the epistemic closure principle. This is the principle that says knowledge is closed under known entailment; or (roughly) if S knows p and S knows that p entails q, then S knows that q. The strategy in question looks to the individual conditions on knowledge to see if they are closed. According to one conjecture, if all the individual conditions are closed, then so too is knowledge. I give a deductive argument for this conjecture. According to a second conjecture, if one (or more) condition is not closed, then neither is knowledge. I give an inductive argument for this conjecture. In sum, I defend the strategy by defending the claim that knowledge is closed if, and only if, all the conditions on knowledge are closed. After making my case, I look at what this means for the debate over whether knowledge is closed. According to the epistemic closure principle (hereafter, Closure), if someone knows that P, knows that P entails Q, goes on to infer Q, and in this way bases their belief that Q on their belief that P and their belief that P entails Q, then they know that Q. Similar principles cover proposed conditions on knowledge. Call the conditions on knowledge, whatever they might be, k-conditions. A k-condition, C, is closed if and only if the following is true: if S meets C with respect to P and S meets C with respect to P entails Q, and S goes on to infer from these to believe Q thereby basing her belief that Q on these other beliefs, then S meets C with respect to Q.1 On one view about the relationship between knowledge and its conditions, Closure is true just in case all k-conditions are closed. -
Interactive Models of Closure and Introspection
Interactive Models of Closure and Introspection 1 introduction Logical models of knowledge can, even when confined to the single-agent perspective, differ in many ways. One way to look at this diversity suggests that there doesn’t have to be a single epistemic logic. We can simply choose a logic relative to its intended context of application (see e.g. Halpern [1996: 485]). From a philosophical perspective, however, there are at least two features of the logic of “knows” that are a genuine topic of disagreement, rather than a source of mere diversity or pluralism: closure and introspec- tion. By closure, I mean here the fact that knowledge is closed under known implication, knowing that p puts one in a position to come to know what one knows to be implied by p. By introspection, I shall (primarily) refer to the principle of positive introspection which stipulates that knowing puts one in a position to know that one knows.1 The seemingly innocuous princi- ple of closure was most famously challenged by Dretske [1970] and Nozick [1981], who believed that giving up closure—and therefore the intuitively plausible suggestion that knowledge can safely be extended by deduction— was the best way to defeat the sceptic. Positive introspection, by contrast, was initially defended in Hintikka’s Knowledge and Belief [1962], widely scrutinized in the years following its publication (Danto [1967], Hilpinen [1970], and Lemmon [1967]), and systematically challenged (if not conclu- sively rejected) by Williamson [2000: IV–V]. A feature of these two principles that is not always sufficiently acknowl- edged, is that that there isn’t a unique cognitive capability that corresponds to each of these principles. -
Logic: a Brief Introduction Ronald L
Logic: A Brief Introduction Ronald L. Hall, Stetson University Chapter 1 - Basic Training 1.1 Introduction In this logic course, we are going to be relying on some “mental muscles” that may need some toning up. But don‟t worry, we recognize that it may take some time to get these muscles strengthened; so we are going to take it slow before we get up and start running. Are you ready? Well, let‟s begin our basic training with some preliminary conceptual stretching. Certainly all of us recognize that activities like riding a bicycle, balancing a checkbook, or playing chess are acquired skills. Further, we know that in order to acquire these skills, training and study are important, but practice is essential. It is also commonplace to acknowledge that these acquired skills can be exercised at various levels of mastery. Those who have studied the piano and who have practiced diligently certainly are able to play better than those of us who have not. The plain fact is that some people play the piano better than others. And the same is true of riding a bicycle, playing chess, and so forth. Now let‟s stretch this agreement about such skills a little further. Consider the activity of thinking. Obviously, we all think, but it is seldom that we think about thinking. So let's try to stretch our thinking to include thinking about thinking. As we do, and if this does not cause too much of a cramp, we will see that thinking is indeed an activity that has much in common with other acquired skills. -
Evidence, Epistemic Luck, Reliability, and Knowledge
Acta Analytica https://doi.org/10.1007/s12136-021-00490-0 Evidence, Epistemic Luck, Reliability, and Knowledge Mylan Engel Jr.1 Received: 8 August 2020 / Accepted: 5 August 2021 © Springer Nature B.V. 2021 Abstract In this article, I develop and defend a version of reliabilism – internal reasons relia- bilism – that resolves the paradox of epistemic luck, solves the Gettier problem by ruling out veritic luck, is immune to the generality problem, resolves the internal- ism/externalism controversy, and preserves epistemic closure. Keywords Epistemic luck · Reliabilism · Generality problem · Internalism/ externalism debate · Personal and doxastic justifcation · Analysis of knowledge 1 A Modest Goal My goal is to develop and defend a version of reliabilism—internal reasons reliabi- lism—that resolves the paradox of epistemic luck, solves the Gettier problem by rul- ing out veritic luck, is immune to the generality problem, resolves the internalism/ externalism controversy, and preserves epistemic closure. Let’s begin! 2 The Epistemic Luck Paradox Epistemic luck is a generic notion used to describe various ways in which it is some- how accidental, coincidental, or fortuitous that a person has a true belief that p. The phenomenon of epistemic luck gives rise to an epistemological paradox. The para- dox is generated by three extremely plausible theses. 2.1 The Knowledge Thesis We know a lot. We possess all sorts of knowledge about the world around us. You know that you are currently reading an article on epistemology. I know that I am looking at a computer screen. You know what city you are currently in. I know that * Mylan Engel Jr. -
The Philosophy of Mathematics: a Study of Indispensability and Inconsistency
Claremont Colleges Scholarship @ Claremont Scripps Senior Theses Scripps Student Scholarship 2016 The hiP losophy of Mathematics: A Study of Indispensability and Inconsistency Hannah C. Thornhill Scripps College Recommended Citation Thornhill, Hannah C., "The hiP losophy of Mathematics: A Study of Indispensability and Inconsistency" (2016). Scripps Senior Theses. Paper 894. http://scholarship.claremont.edu/scripps_theses/894 This Open Access Senior Thesis is brought to you for free and open access by the Scripps Student Scholarship at Scholarship @ Claremont. It has been accepted for inclusion in Scripps Senior Theses by an authorized administrator of Scholarship @ Claremont. For more information, please contact [email protected]. The Philosophy of Mathematics: A Study of Indispensability and Inconsistency Hannah C.Thornhill March 10, 2016 Submitted to Scripps College in Partial Fulfillment of the Degree of Bachelor of Arts in Mathematics and Philosophy Professor Avnur Professor Karaali Abstract This thesis examines possible philosophies to account for the prac- tice of mathematics, exploring the metaphysical, ontological, and epis- temological outcomes of each possible theory. Through a study of the two most probable ideas, mathematical platonism and fictionalism, I focus on the compelling argument for platonism given by an ap- peal to the sciences. The Indispensability Argument establishes the power of explanation seen in the relationship between mathematics and empirical science. Cases of this explanatory power illustrate how we might have reason to believe in the existence of mathematical en- tities present within our best scientific theories. The second half of this discussion surveys Newtonian Cosmology and other inconsistent theories as they pose issues that have received insignificant attention within the philosophy of mathematics. -
Validity and Soundness
1.4 Validity and Soundness A deductive argument proves its conclusion ONLY if it is both valid and sound. Validity: An argument is valid when, IF all of it’s premises were true, then the conclusion would also HAVE to be true. In other words, a “valid” argument is one where the conclusion necessarily follows from the premises. It is IMPOSSIBLE for the conclusion to be false if the premises are true. Here’s an example of a valid argument: 1. All philosophy courses are courses that are super exciting. 2. All logic courses are philosophy courses. 3. Therefore, all logic courses are courses that are super exciting. Note #1: IF (1) and (2) WERE true, then (3) would also HAVE to be true. Note #2: Validity says nothing about whether or not any of the premises ARE true. It only says that IF they are true, then the conclusion must follow. So, validity is more about the FORM of an argument, rather than the TRUTH of an argument. So, an argument is valid if it has the proper form. An argument can have the right form, but be totally false, however. For example: 1. Daffy Duck is a duck. 2. All ducks are mammals. 3. Therefore, Daffy Duck is a mammal. The argument just given is valid. But, premise 2 as well as the conclusion are both false. Notice however that, IF the premises WERE true, then the conclusion would also have to be true. This is all that is required for validity. A valid argument need not have true premises or a true conclusion.