DOCSLIB.ORG

Transaction Logic: Unifying Declarative and Procedural Knowledge - Extended Abstract

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Transaction Logic: Unifying Declarative and Procedural Knowledge - Extended Abstract From: AAAI Technical Report FS-93-01. Compilation copyright © 1993, AAAI (www.aaai.org). All rights reserved. Transaction Logic: Unifying Declarative and Procedural Knowledge - Extended Abstract - Anthonyt J. Bonner* and Michael Kifer 1 Introduction that check the context and then prescribe different se- quences of actions, depending on the outcome [26]. Like- This paper presents AI applications of the recently pro- wise, the classic planning system STRIPS[6] is based on posed Transaction Logic (abbr., 7-7z) [2]. Transaction procedurally-defined actions, which STRIPS combines Logic is a novel formalism that accounts in a clean into plans that achieve larger goals. Section 6.1 shows and declarative fashion for the phenomenon of updat- that STRIPSis representable in q-n and that its infer- ing first-order knowledge bases, most notably, databases ence rules are sound. Even though STRIPS was given and logic programs. Transaction Logic has a natural formal semantics in [16], this was not done within a log- model theory and a sound-and-complete proof theory. ical formalism (and, unlike [16], STRIPSis just one of Unlike many other logics, Tn allows users to program the many applications of Tn). transactions that modify the state of a knowledge base. At first glance, there might seem to be many candi- This is possible because, like classical logic, Tn has dates for a logic of procedural knowledge, since many a "Horn" version which has both a procedural and a logics reason about updates or about the related phe- declarative semantics, as well as an efficient SLD-style nomena of time and action. We have found, however, proof procedure. As a result, Tn is a unifying, logical that none of them is suitable for representing and using formalism for specifying both declarative and procedu- procedural knowledge. First, most logics of time or ac- ral knowledge. Furthermore, for a wide range of prac- tion are hypothetical: Instead of executing procedures, tical problems, the frame problem [18] is not an issue they reason about them, or about what would happen for "/-n. This is because Tn performs real updates on if certain actions were to take place. For instance, some materialized databases, much as procedural languages systems can infer that if action A precedes B, and B pre- like Pascal do. A key contribution of ~-n is capturing cedes C, then A must precede C. Others can infer that these procedural updates in a logical framework with if a student took history 400, then he could graduate. an efficient proof theory. A full development of the Such systems were intended to be observers of action, proof theory, a discussion of the frame problem, and not participants. They are therefore useful for reason- applications to database systems can be found in [2, ing about alternatives, or for analyzing programs and 3]. This paper presents the model theory of 7-~¢, and plans; but they are not very useful for defining proce- then focuses on applications of Tn to problems in AI, dures that actually accomplish state changes being rea- especially planning, temporal reasoning, constraint sat- soned about. In 7-~¢, actions can be carried out hypo- isfaction, hypothetical and counterfactual reasoning, and thetically or they can be executed and have a permanent the representation and use of procedural knowledge. effect on the knowledge base, depending on one’s desire. The importance of procedural knowledge has been In this way procedural knowledge can be used as well as extensively argued in the AI literature (see e.g., [8]). represented and reasoned about. For instance, the well-known SHRDLUprogram [26] is The second problem with many action logics is that largely based on procedural knowledge. In fact, Wino- it is awkward,if not impossible to assign names to com- grad argues in [26] that procedural knowledgeis inherent posite actions. Such logics were designed for reasoning in automated natural language understanding. For ex- about sequences of actions, not for programming them. ample, the meaningof "the" is a collection of procedures As such, they are inappropriate for defining actions since a namingfacility is needed for representing even very ba- *Department of Computer Science, University of sic procedural knowledge;i.e., specifying actions without Toronto, Toronto, Ontario MbS 1A4, Canada; bon- a naming facility is akin to programming without sub- [email protected]. Work supported in part by an Oper- ating Grant from the Natural Sciences and Engineering Re- routines. This defeats the purpose of using logic in the search Council of Canadaand by a Connaught Grant from first place, which is to free the user from the drudgery the University of Toronto. of low-level details. tDepartment of Computer Science, SUNY-StonyBrook, Third, many logics make a clear distinction between Stony Brook, NY11794, U.S.A.; [email protected]. Work queries and updates. However,this distinction is blurred supported in part by NSFgrant CCR-9102159. in object-oriented systems, where both queries and up- 17 dates are special cases of a single idea: method invo- is best for all purposes [2]. Thus, rather than commit cation. In such systems, an update can be thought of Tn to a fixed set of elementary transitions, we have cho- as a query with side effects. We would like to model sen to treat the elementary transitions as a parameter this behavior and thereby provide a logical foundation of Tze. Each set of elementary transitions thus gives for object-oriented databases. Tn achieves this by al- rise to a different version of the logic. To achieve this, lowing every logical formula to have not only a truth elementary transitions are defined by logical axioms. value, but also a "side effect" on the database. In this Elementary transitions are formulas of the form way, one can account for the behavior of object-oriented (¢, ¢)u, where ¢, ¢ are (sets of) closed first-order databases--something that most formalisms do not do. mulas and u is an atomic formula, called the name of In combination with F-logic [13], the structural aspects the transition. Intuitively, this formula says that u is of object-oriented systems can be accounted for as well. an update that transforms database ¢ into database ¢. The system that comes closest in spirit to T7¢ is Pro- For instance, if the atoms ins:q(t) and del:q(t) stand for log. Unfortunately, updates in Prolog are non-logical the insertion and deletion of the atom q(t), then they and, as a result, state-changing procedures are often the would be defined by an enumerable set of elementary most awkward of Prolog programs, and the most diffi- transitions consisting of the following formulas: cult to understand, debug, and maintain. Semantically Tn is closely related to Process Logic [11], but is differ- (D, D + {q(t)}) ins:q(t) (D, D - {q(t)}) del:q(t) ent from it in several important ways detailed in [2]. for every relational database, D.x Enumerable sets of Due to space limitation, many topics are merely elementary transitions are called transition bases. In sketched in this paper. Details appear in [2]. practice, these formulas would not be materialized all at once, but would be generated on demand by an algo- 2 Syntax rithm. We refer to [2] for a more detailed discussion of The syntax of Tn distinguishes two kinds of formulas: transition bases. As seen from the syntax, q-~e does not strictly distin- transaction formulas and elementary transitions. The guish between predicates that query the knowledge base former define composite transactions, and the latter de- and predicates that update it. As in classical logic, ev- fine elementary updates. ery predicate has a truth value; but in addition, every Transaction formulas, which extend first-order for- predicate may also have a side effect, by changing the mulas with a new connective, ®, called serial con- junction, are used to define transactions and formulate state of the knowledge base. This uniformity of repre- sentation is important in modeling methods (interface queries. Transaction formulas are defined as follows. An atomic transaction formula is an expression of the form functions encapsulated inside classes) in object-oriented databases, where one generally does not distinguish be- p(tl,...,t,~), where p E P is a predicate symbol, and tween information-retrieving and state-changing meth- tl,...,t,, are terms (as in classical predicate calculus). ods. Nevertheless, if desired, 7-Te can make such a dis- If ¢ and ¢ are transaction formulas, then so are ¢ V ¢, tinction by using different sorts of predicates, one for ¢^¢, ¢®¢, -,¢, (VX)¢, and (3X)¢, whereXisa updates and one for queries. variable. Thus, the expression a(X) V --,[b(X) c(X, Y) For instance, it is good programmingpractice to re- is a transaction formula. Intuitively, ¢®¢ means, "Do ¢, then do ¢." A dual connective, serial disjunction, is also serve a special set of predicates for certain basic updates. This paper uses just such a convention: for each predi- useful (Section 6.2): ¢ ~ ¢ is equivalent to --,(-~¢ ® -1¢). cate symbol p, we use another predicate symbol, ins:p, Serial conjunction provides a basic way to sequence to represent insertions of tuples into p. Likewise, we rep- transactions, where ¢ @¢ means "do ¢, then do ¢." resent deletions from p by the predicate del:p. Thus the In contrast, classical conjunction, "A", constrains the formula ins:p(a) ® ins:p(b) ~, ins:p(c) represents an up- non-determinism of a transaction. For instance, ¢ A ¢ dating transaction that inserts p(a) into the database, means, "do ¢ in a way compatible with doing ¢." This then p(b), and then p(c). use of "A" is further discussed in Section 6.2. Apart from this, "A" also has the traditional role of forming Blocks-World Example logic programs: in Tn, as in classical logic, any finite 3 set of rules is equivalent to a conjunction of all the rules Before presenting the semantics, we illustrate the syn- in the set.
Load more

Recommended publications
  • ED305329.Pdf
    DOCUMENT RESUME ED 305 329 SP 030 956 AUTHOR Sarvimaki, Anneli TITLE Knowledge in Interactive Practice Disciplines. An Analysis of Knowledge in Education and Health Care. Research Bulletin 68. INSTITUTION Helsinki Univ. (Finland). Dept. of Education. REPORT NO ISBN-951-45-4787-X PUB DATE 88 NOTE 292p. PUB TYPE Reports - Research/Technical (143) EDRS PRICE MF01/PC12 Plus Postage. DESCRIPTORS *Educational Objectives; Educational Philosophy; Educational Practices; *Educational Principles; Health Promotion; *Interaction; Sociolinguistics; *Theory Practice Relationship; Values ABSTRACT This study formulates a conception of knowledge in interactive practice disciplines such as education and health care and clarifies different types of knowledge in these disciplines. Focus is on the relationship between practical and theoretical knowledge. Four theses are discussed: (1) the role of knowledge in an interactive practice is to guide practice; (2) different types of knowledge in an interactive practice consist of value-knowledge, factual knowledge and procedural knowledge, parts of which are unarticulated, parts articulated; (3) science is a way of articulating and creating knowledge that can be used as internal action determinants in the practice concerned; and (4) theories in an interactive practice can have both a theoretical and a practical purpose but the theoretical purpose is also indirectly linked to the practical. (Author/JD) "t***************************************************2****************** * Reproductions supplied by EDRS are the
    [Show full text]
  • Procedural and Declarative Knowledge an Evolutionary Perspective
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by DSpace at Open Universiteit Nederland Procedural and Declarative Knowledge An Evolutionary Perspective Timon ten Berge Ren´e van Hezewijk Vrije Universiteit Utrecht University Abstract. It appears that there are resemblances in the organization of memory and the visual system, although the functions of these faculties differ considerably. In this article, the principles behind this organization are discussed. One important principle regards the distinction between declarative and procedural knowledge, between knowing that and knowing how. Declarative knowledge is considered here not as an alternative kind of knowledge, as is usually the case in theories of memory, but as part of procedural knowledge. In our view this leads to another approach with respect to the distinction. Declarative knowledge has occupied more attention in (cognitive) psychological research than can be justified on the basis of the importance of procedural knowledge for behavior. We also discuss the question whether there are other brain faculties that reflect the same organizational characteristics. We conclude with some speculations about the consequent role of consciousness in such a tentative model. KEY WORDS: declarative knowledge, evolutionary psychology, memory, procedural knowledge, vision Introduction: Modularity in the Human Brain Traditionally, cognitive psychology has viewed the human mind as a general information-processing device. On this view, a human being is born with a set of general reasoning capacities that can be used when confronted with any problem. A growing number of researchers are supporting a view of the human brain as an organized collection of specialized modules, each with its own domain-specific knowledge and responses.
    [Show full text]
  • Mapping the Meaning of Knowledge in Design Research Kristina Niedderer University of Hertfordshire
    V.2:2 April 2007 www.designresearchsociety.org Design Research Society ISSN 1752-8445 Mapping the Meaning of Knowledge in Design Research Kristina Niedderer University of Hertfordshire Knowledge plays a vital role in our life This question has arisen for design in Table of Contents: in that it reflects how we understand the UK, as well as more generally for the world around us and thus deter- creative and practice-led disciplines Articles: 1 Mapping the Meaning of Knowledge mines how we act upon it. In this sense, (CPDs), because research regulations in Design Research knowledge is of particular importance and requirements in the UK remain Kristina Niedderer for designers because they act to shape silent about what knowledge and our world. Conventionally, knowledge understanding mean in the context of 3 Call for Papers: Design Research creation has been assumed by (design) their specifications while implicitly pri- Quarterly research. However developments of oritising propositional knowledge over Case Studies in Research: Knowledge using practice within research have knowledge that cannot be expressed in and Inquiry pointed to knowledge creation within that form (Niedderer 2007). and through practice. This has raised This has led to a number of prob- Listings: the question of the meaning, role and lems concerning the role and format 14 Current Research in Design: format of knowledge in both research of knowledge in research and practice ToCs from Leading Design Journals and practice, and about the compatibil- in the UK. For example, because of the ity between knowledge of research and language-based mode of proposition- 21 Upcoming Events Worldwide practice.
    [Show full text]
  • Descartes' Hostages: Mind and Observability in Education
    Descartes’ Hostages: Mind and Observability in Education by Shannon Rodgers B.A. (Hon.), Simon Fraser University, 1994 Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy In the Curriculum Theory & Implementation: Philosophy of Education Program Faculty of Education © Shannon Rodgers 2017 SIMON FRASER UNIVERSITY Summer 2017 Copyright in this work rests with the author. Please ensure that any reproduction or re-use is done in accordance with the relevant national copyright legislation. Approval Name: Shannon Rodgers Degree: Doctor of Philosophy Title: Descartes’ Hostages: Mind and Observability in Education Examining Committee: Chair: Dr. Stephen Smith Teaching Professor Dr. Charles Bingham Senior Supervisor Professor ___________________________________________ Dr. Heesoon Bai Supervisor Professor ___________________________________________ Dr. Sean Blenkinsop Supervisor Assistant Professor ___________________________________________ Dr. Allan MacKinnon Internal Examiner Associate Professor ___________________________________________ Dr. Taylor Webb External Examiner Associate Professor Dept. of Educational Studies University of British Columbia ___________________________________________ Date Defended/Approved: June 14th, 2017 ii Ethics Statement iii Abstract My purpose in this dissertation is to argue that given the relationship among the concepts of mind, knowledge, education and assessment, educators must pay more attention to our current view of mind. Educators use assessment practices,
    [Show full text]
  • A Knowledge Concept Map: Structured Concept Analysis from Systematic Literature Review
    29 a Knowledge Concept Map: Structured Concept analysis from Systematic literature review Philip Sisson1 and Julie J.C.H. Ryan2 Abstract The purpose of this article is to present a mental model of knowledge as a concept map as an input to knowledge management (KM) investigations. This article’s extended knowledge concept map can serve as a resource where the investigation, development, or application of knowledge would be served with a broad mental model of knowledge. Previously unrelated concepts are related; knowledge concepts can sometimes be expressed as a range, i.e., certainty related states: view, opinion, sentiment, persuasion, belief, and conviction. Extrathesis is identified as a potential skill level higher than synthesis, and associated with the concepts: discovery, institution, insight (the event), revelation, or illumination that precedes innovation. Qualitative methods were used to gather and document concepts. System engineering and object analysis methods were applied to define and relate concepts. However, the theoretical sampling and theoretical saturation methods applied do not guarantee all appropriate concepts have been identified. Given the breadth, depth, and dimensionality of concepts of knowledge, later researchers may add additional concepts. This article provides evidence of additional things people know, an alternative to psychology’s acquaintanceship, understanding and placement of newer categorizations of knowledge in relation to older ones, and suggests that ranges for knowledge terms exist. This article extends the 2015 paper on this topic by: 1) taking a deeper look into epistemological terms and relationships, 2) providing contextual definitions, 3) suggesting extrathesis as an idea beyond synthesis, 4) updating the concept map; and 5) providing new insight on the overloaded knows including adding an eleventh know.
    [Show full text]
  • The Spaces of Data, Information, and Knowledge
    The Spaces of Data, Information, and Knowledge Xiaoyu Chena and Dongming Wangb,c Abstract We study the data space D of any given data set X and explain how functions and relations are defined over D. From D and for a specific domain ∆ we construct the information space I of X by interpreting variables, functions, and explicit relations over D in ∆ and by including other relations that D implies under the interpretation in ∆. Then from I we build up the knowledge space K of X as the product of two spaces KT and KP , where KT is obtained from I by using the induction principle to generalize propositional relations to quantified relations, the deduction principle to generate new relations, and standard mechanisms to validate relations and KP is the space of specifications of methods with operational instructions which are valid in KT . Through our construction of the three topological spaces the following key observation is made clear: the retrieval of information from the given data set for ∆ consists essentially in mining domain objects and relations, and the discovery of knowledge from the retrieved information consists essentially in applying the induction and deduction principles to generate propositions, synthesizing and modeling the information to generate specifications of methods with operational instructions, and validating the propositions and specifications. Based on this observation, efficient approaches may be designed to discover profound knowledge automatically from simple data, as demonstrated by the result of our study in the case of geometry. Keywords data space, declarative knowledge, deduction principle, implied knowledge, induction principle, information retrieval, knowledge discovery, procedural knowledge, quantified relation arXiv:1411.1497v1 [cs.AI] 6 Nov 2014 1 Introduction With increasingly wide use of digital devices and networks, more and more scientific explorations and social activities are carried out electronically, where the involved objects, phenomena, and behaviors of interest are measured and presented in the form of data.
    [Show full text]
  • Outcome Evaluation and Procedural Knowledge in Implicit Learning
    Outcome Evaluation and Procedural Knowledge in Implicit Learning Danilo Fum ([email protected]) Department of Psychology, University of Trieste Via S.Anastasio 12, I-34134, Trieste, Italy Andrea Stocco ([email protected]) Department of Psychology, University of Trieste Via S.Anastasio 12, I-34134, Trieste, Italy Abstract form. Starting from the 90s, however, it has been suggested that many results could be explained by Although implicit learning has been considered in recent supposing that participants acquire concrete, fragmentary, years as a declarative memory phenomenon, we show that a declarative knowledge of the task represented through procedural model can better elucidate some intriguing and instances. Instance-based knowledge has indeed been unexpected data deriving from experiments carried out with Sugar Factory (Berry & Broadbent, 1984), one of the most shown to underlie or significantly affect performance on popular paradigms in this area, and can account for other artificial grammar learning (Perruchet & Pacteau, 1990), phenomena reported in the literature that are at odds with sequence prediction (Perruchet, 1994) and dynamic current explanations. The core of the model resides in its system control tasks (Dienes & Fahey, 1995; Lebiere, adaptive mechanism of action selection that is related to Wallach & Taatgen, 1998, Taatgen & Wallach, 2002). outcome evaluation. We derived two critical predictions In this paper we will focus on a widely adopted from the model concerning: (a) the role of situational dynamic system control task known as Sugar Factory factors, and (b) the effect of a change in the criterion (Berry & Broadbent, 1984). In this task, henceforth SF, adopted by participants to evaluate the outcome of their participants are asked to imagine themselves in chief of a actions.
    [Show full text]
  • Mind, Machines and Language
    Mind, Machines and Language ELL457/HUL381 [Slides by Santanu Chaudhury, Hiranmay Ghosh, and Sumeet Agarwal] [Material sourced from Friedenberg and Silverman, 2006] Introduction: Philosophical & Psychological Perspectives “The sciences have developed in an order the reverse of what might have been expected. What was most remote from ourselves was first brought under the domain of law, and then, gradually, what was nearer: first the heavens, next the earth, then animal and vegetable life, then the human body, and last of all (as yet very imperfectly) the human mind.” —Bertrand Russell, 1935 Neuroscience Electrical Engineering Psychology and Cognitive Science Computer Science Philosophy Linguistics Cognitive Science: Mind as Computer ● Representation ➔ Concepts ➔ Propositions ➔ Rules ➔ Analogies ➔ Digital (symbols) ➔ Analog (images) ● Transformation/Processing/Computation Example: Analogical reasoning [Duncker '45] Suppose you are a doctor faced with a patient who has a malignant tumor in his stomach. To operate on the patient is impossible, but unless the tumor is destroyed, the patient will die. A kind of ray, at a sufficiently high intensity, can destroy the tumor. Unfortunately, at this intensity the healthy tissue that the rays pass through on the way to the tumor will also be destroyed. At lower intensities the rays are harmless to healthy tissue, but will not affect the tumor. How can the rays be used to destroy the tumor without injuring the healthy tissue? Analogy A small country was ruled from a strong fortress by a dictator. The fortress was situated in the middle of the country, surrounded by farms and villages. Many roads led to the fortress through the countryside.
    [Show full text]
  • Representation of Procedural Knowledge
    NEW MEXICO STATE UNIVERSITY COMPUTER SCIENCE DEPARTMENT Representation of Procedural Knowledge Roger T Hartley Abstract A case is made for correcting a perceived imbalance between the usual ways of representing declarative and procedural knowledge. A proposed solution joins the traditional conceptual graph notation and elements of visual programming languages. The aim is to maintain the visual nature of both notations without greatly changing each one. Representation of Procedural Knowledge 1. Introduction We start with the premise that there is a clear duality between declarative and procedural knowledge [Ryle, 1949]. One form of knowledge is inadequate without the other, and thus choosing one form of knowledge over the other for any reason would lead to philosophical falsehoods at worst, or a serious neglect at best. We believe that there has been such a neglect of procedural knowledge over the course of history, rooted in our human predilection for language on the one hand, and pictures on the other. Add to this that we are still puzzled over the nature of time. It has only recently, and reluctantly, been incorporated into our understanding of the physical world as an equal to space. Processes are hard to perceive, hard to understand, and, in the end, get the short end of the theoretical stick. We are much happier with observable measurement - the visual realm again - and static relationships between relatively fixed quantities. This paper is a brief investigation of the nature of the duality between the two types of knowledge, and their representation for processing in computer form. Our preference for the conceptual graph formalism will lead us to a particular set of choices for representing procedural knowledge so that the perceived imbalance with declarative knowledge can be redressed.
    [Show full text]
  • A Truth-Based Epistemological Framework for Supporting Teachers in Integrating Indigenous Knowledge Into Science Teaching
    A Truth-Based Epistemological Framework for Supporting Teachers in Integrating Indigenous Knowledge into Science Teaching Gracious Zinyeka*, Gilbert O.M. Onwu and Max Braun Department of Science Mathematics & Technology Education, University of Pretoria, Pretoria, South Africa *Corresponding author. 713 Popgum Road, Greenhill, Bindura, Zimbabwe. Email: [email protected] Integrating indigenous knowledge (IK) into school science teaching is one way of maximising the socio- cultural relevance of science education for enhanced learners’ performance. The epistemological differences however between the nature of science (NOS) and nature of indigenous knowledge (NOIK) constitute a major challenge for an inclusive IK-science curriculum integration. This article is about the application of a truth-based epistemological framework designed to support teachers to make decisions on how specific pieces of indigenous knowledge (local traditional practices and technologies) may be included in science lessons. First, an attempt was made to develop a truth-based epistemological framework for identifying epistemology(ies) of indigenous knowledge and practices. Second a group of science teachers used the truth-based epistemological framework to examine ways in which some specified IK practices that comprised a coherent set of knowledge themes on health, agriculture and technology could be integrated into the school science curriculum in a valid and legitimate way. The IK practices used in the study were systematically identified and documented by means of personal observations and interviews of key informants in a rural community in Zimbabwe. The main findings of the study showed that the truth-based epistemological framework was useful in providing an epistemological basis for including some IK practices in science teaching and learning.
    [Show full text]
  • Notes on Knowledge Gary Hardegree Department of Philosophy University of Massachusetts Amherst, MA 01003
    Notes on Knowledge Gary Hardegree Department of Philosophy University of Massachusetts Amherst, MA 01003 1. Introduction......................................................................................................................................1 2. Epistemology ...................................................................................................................................2 3. The Verb ‘Know’.............................................................................................................................2 4. Propositional Attitudes and Propositional Adjectives .....................................................................4 5. Propositions......................................................................................................................................5 6. The Distinction between Sentences and Propositions......................................................................6 7. The Ubiquitous ‘That’......................................................................................................................6 8. Direct versus Indirect Quotation......................................................................................................7 9. Sentential Attitudes and Properties..................................................................................................8 10. The Ubiquitous ‘It’...........................................................................................................................9 11. Sentential Attitudes can be Weird..................................................................................................10
    [Show full text]
  • 2019-01-08 Peels on El Kassar
    http://social-epistemology.com ISSN: 2471-9560 Exploring the Boundaries of Ignorance: Its Nature and Accidental Features Rik Peels, Vrije Universiteit Amsterdam –––––––––––––––––– Peels, Rik. “Exploring the Boundaries of Ignorance: Its Nature and Accidental Features.” Social Epistemology Review and Reply Collective 8, no. 1 (2019): 10-18. Short url: https://wp.me/p1Bfg0-456 (provided by WordPress) Vol. 8, no. 1 (2019): 10-18. https://wp.me/p1Bfg0-456 Nadja El Kassar is right that different fields in philosophy use rather different conceptions of ignorance. I also agree with her that there seem to be three major conceptions of ignorance: (i) ignorance as propositional ignorance, which she calls the ‘propositional conception of ignorance’, (ii) ignorance as actively upheld false outlooks, which she names the ‘agential conception of ignorance’, and (iii) ignorance as an epistemic practice, which she dubs the ‘structural conception of ignorance’. It is remarkable that nobody else has addressed the question before of how these three conceptions relate to each other. I consider it a great virtue of her lucid essay that she not only considers this question in detail, but also provides an account that is meant to do justice to all these different conceptions of ignorance. Let us call her account the El Kassar Synthesis. It reads as follows: Ignorance is a disposition of an epistemic agent that manifests itself in her beliefs – either she has no belief about p or a false belief – and her epistemic attitudes (doxastic attitudes, epistemic virtues, epistemic vices).1 My reply to her insightful paper is structured as follows. First, I argue that her synthesis needs revision on various important points (§2).
    [Show full text]