C.S. Peirce's and Isaac Levi's accounts of the belief-doubt-belief model are discussed and evaluated. It is argued that the contemporary study of belief change has metamorphosed into a branch of philosophical logic where empirical considerations have become obsolete. A case is made for reformulations of belief change systems that do allow for empirical tests. Last, a belief change system is presented that (1) uses finite representations of information, (2) can adequately deal with inconsistencies, (3) has finite operations of change, (4) can do without extra-logical elements, and (5) only licenses consistent beliefs

Tamminga, Allard

English

PhilPapers

Belief Dynamics: (Epistemo)logical Investigations

Tamminga, A.M.

UvA-DARE

International Migration, Integration and Social Cohesion online publications

UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)UvA-DARE (Digital Academic Repository)Belief Dynamics: (Epistemo)logical InvestigationsTamminga, A.M.Publication date2001Link to publicationCitation for published version (APA):Tamminga, A. M. (2001). Belief Dynamics: (Epistemo)logical Investigations. [Thesis, fullyinternal, Onderzoeksschool Logica / ILLC]. ILLC.General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an opencontent license (like Creative Commons).Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, pleaselet the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the materialinaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letterto: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. Youwill be contacted as soon as possible.Download date:15 Apr 2023Chapterr 5 Conclusion n 5.11 Summary of the Results Thee introductory chapter served to present the belief-doubt-belief model that was firstfirst conceived within 19th century American pragmatism, in an attempt to recon-cilee the theory of knowledge with the insights from Darwin's evolutionary biology. Thus,, an alternative for Aristotle's ideal of knowledge was developed, an alterna-tivee that can do without the assumption that science needs a secure foundation inn the form of a set of evident axioms from which all truths can be deduced. It wass shown that attempts, still inspired by the demands of traditional philoso-phy,, to define the concepts of truth and reality in terms of the newly conceived belief-doubt-beliefbelief-doubt-beliefmodelmodel are, to say the least, somewhat premature. Instead, it wass proposed to focus our attention on more precise formulations of the model. Consequently,, the logical epistemology of the most prominent contemporary advocatee of the belief-doubt-beliej'model, Isaac Levi, has been expounded at length inn the third chapter. In the course of this exposition, serious drawbacks of the approachh favoured by Levi came to the fore. Levi's claims to construct a nor-mativee theory about belief change could not be substantiated, let alone that his theoryy admits an empirical test. These characteristics are unacceptable. In the facee of recent pleas, among others from naturalistic philosophers, for empirical evaluationss of philosophical theories, it was argued that the field of belief change urgentlyy needs a reformulation in order to make possible empirical assessments of thee merits of the proposed theories. A fruitful way to addres this reformulation problemm would be an approach that concentrates on eliminating parameters in theoriess about belief change which have withstood practical assessment so far. Inn the fourth chapter, this new program for the field of belief change was carriedd out in detail. First, by representing the information offered as a finite state,state, we avoided the computational problems that are posed by representations off  information by deductively closed sets of sentences. Second, rather than rely on 91 1 92 2 ChapterChapter 5. Conclusion extra-logicall  considerations in the definition of contraction, the newly proposed systemm had a purely logical contraction operator. Third, unlike the host of the systemss for belief change that have been presented in the literature, the system couldd cope with inconsistencies, which, if necessary, could be removed one by one. \Vee have not only developed techniques to change a finite state via expansion orr contraction, but have indicated methods to extract consistent 'beliefs' from inconsistentt finite states as well.1 Iss this all there is? Obviously, there is much more to belief change than avoidingg bewilderment in the presence of contradictions: Diee Anpassung der Gedanken aneinander erschöpft sich nicht in der Abschleifungg der Widersprüche. [...] Das Ökonomisieren, Harmon-isieren.. Organisieren der Gedanken, welches wir als ein biologisches Bedürfniss fühlen. geht weit über die Forderung der logischen Wider-spruchslosigkeitspruchslosigkeit hinaus. [Mach. 1905. p. 176] 5.22 Future Work Sincee the publication of Quine's programmatic 'Epistemology Naturalized' (1969), inn which Quine prompts to undertake empirical investigations into the connec-tionss between our 'theory of the world1 and our sensory stimuli,2 epistemologists havee become more and more interested in something which could be called aptly metanaturalism.metanaturalism. Rather than concentrate on the construction and evaluation off  theories about cognition, the contemporary philosophical discussion has been limitedd largely to the Kant-style question as to how, in the face of the demise of rationalisticc approaches to epistemology, a naturalistic epistemology might still bee possible. (In the meantime, cognitive psychologists, neurologists, logicians and researcherss within AI do the jobs epistemologists used to do.) Thee recent collection of essays Naturalismus (2000), edited by the German philosopherss Keil and Schnadelbach, is a case in point. In an introductory essay, thee editors addres the problem of defining the term 'naturalism', discussing sev-enteenn proposals for a definition. Koppelberg, in his contribution, makes clear thatt naturalism must not be equated to empiricism, fysicalism, scientism, or an-timentalism.. Moreover, the editors claim "dafi sich mit der Opposition gegen denn Supranaturalismus heute keine interessante Position mehr markieren lafit" lrThee extractors, which have been defined in the last section of the fourth chapter, fulfil l att least one of Nuel Belnap's wishes: "The complete reasoner should, presumably, have some strategyy for giving up part of what it believes when it finds its beliefs inconsistent. [...] I havee never heard of a practical, reasonable, mechanizable strategy for revision of belief in the presencee of contradiction" [Belnap, 1977, p. 9]. 22 "The stimulation of his sensory receptors is all the evidence anybody has had to go on. ultimately,, in arriving at his picture of the world. Why not just see how this construction really proceeds?'""  [Quine, 1969, p. 75.] 5.2.5.2. Future Work 93 3 [Keill  and Schnadelbach, 2000, p. 31]. The present thesis has shown that, although antirationalismm might not be worth the trouble of yet another philosophical de-fense,, traces of rationalistic theorizing abound in contemporary epistemology and philosophicall  logic. Byy and large, the discussion in the belief change literature has been focussed largelyy on technicalities and on a priori argumentations in favor of a specific choicee of a set of postulates. Lots of different systems have been proposed, lots off  different formal desiderata have been formulated and defended, usual on the basiss of concise, a priori argumentations, that ultimately rely on pre-theoretical intuitions.. As a starting phase, this is how it should be. It would be a mistake, however,, never to leave the formal considerations for what they are and go on too try to put the proposed systems to an empirical test. Only by testing formal belieff  change theories empirically, can convincing arguments for or against a spe-cificc approach be found, since it would not be the first time in philosophical or mathematicall  research that exclusive reliance on intuitions led us astray. After all,, unlike research in, for example, modal logic, investigations into belief change doo purport to explain some phenomena in an empirical domain. It would be a gravee mistake to conceive of belief change research as a wholly rationalistic (in thee philosophical sense of the word) matter. Thee investigations that have been conducted in the present thesis have, of course,, not been empirical. Nevertheless, they have made an empirical test pos-sible,, because of the elimination of extra-logical considerations in the definition off  contraction. Hence, the system presented in the fourth chapter ought to be seenn as an attempt to 'pragmatize' the field of belief revision,3 that is, to make thee field of belief revision more conducive to empirical considerations than sys-temss advocated by Levi, by Alchourrón, Gardenfors and Makinson, and by their sympathizers. . Thus,, instead of indulging in purely academic debates concerning the proper definitionn of naturalism, in my opinion, the spirit of the naturalized epistemology programmee is better served by a close examination of contemporary theories aboutt cognition. We should detect those elements in these theories that obstruct empiricall  ways of assessing their merits. We should reformulate theories which possess such elements in order to make empirical evaluations of them possible. Butt most of all, we should actually carry out these empirical tests and revise ourr theories according to their outcomes. In the present thesis, the first and secondd points have been put into practice. The third point, applied to the subject matterr of the present thesis, could be implemented, for instance, by the following 33 "Such a pragmatization brings an already existing theory a system - into closer contact withh the empirical world and with practical life, and this, in turn, can inspire empirical research off  different kinds, which may seem irrelevant as long as the theory (for instance, the logical system)) is presented in its original objectivistic or solipsist-subjectivistic garb. Perhaps, prag-matizingg can not be called empirical research, but we may characterize it as a proto-empirical activity.""  [Barth, 1987, p. 11 my translation; AMT.] 94 4 ChapterChapter 5. Conclusion program: : Firstt and foremost, an empirical test of the fourth chapter's system for be-lieff  change has to be carried out. In collaboration with cognitive psychologists, testt conditions must be specified in detail. Great care must be taken that the informationn offered is really considered equally trustworthy by the test subjects. Thiss can be partly realized, for instance, by making sure that the test subjects acknowledgee that the order in which the information is offered to them is wholly arbitrary.. Moreover, the information must be selected in such a way, that the testt subjects have as few preconceived opinions as possible about the relative plausibilityy of the information offered. Then, prompted by logical theory, strate-gicc questions should be asked relating to the plausibility of selected propositions. Thee test subjects should answer these questions solely on the basis of logic and thee controlled information they received previously. Next, of course, it should be checkedd whether their answers are more or less in line with the answers provided byy our system for belief change. Furthermore,, it would certainly be of interest to generalize the theory of belief changee that was presented in the fourth chapter to include not only equable reliablee sources, but sources that differ in trustworthines as well. Though such a generalizationn would hardly affect the logic of the system, it would, first, facilitate aa comparison with belief change systems in the tradition initiated by Levi and byy Alchourrón, Gardenfors and Makinson, since in such a generalized system as welll  as in traditional belief change systems, extra-logical considerations do play aa role. Second, as attributions of trustworthines do play a role in the real-life evaluationn of received information, the generalized theory purports to cover more phenomenaa than the original theory. Thee reintroduction of extra-logical elements would, however, fall short of be-ingg an advance, unless well-argued methods are set forth according to which thee relative trustworthines of the sources can be assessed. Here, philosophical, psychologicall  and economical literature on trust wil l prove relevant. Moreover, aa multi-agent perspective seems to be incumbent, since the assessment of the trustworthiness of a source does not amount to the discovery of a timeless and objectivee property, but wil l rather be the assessment of a function, that might changee over time, of experiences the assessing agent has had with this source and withh other sources as well. 

UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)UvA-DARE (Digital Academic Repository)Belief Dynamics: (Epistemo)logical InvestigationsTamminga, A.M.Publication date2001Link to publicationCitation for published version (APA):Tamminga, A. M. (2001). Belief Dynamics: (Epistemo)logical Investigations. ILLC.General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an opencontent license (like Creative Commons).Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, pleaselet the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the materialinaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letterto: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. Youwill be contacted as soon as possible.Download date:25 Jul 2022Chapterr 5 Conclusion n 5.11 Summary of the Results Thee introductory chapter served to present the belief-doubt-belief model that was firstfirst conceived within 19th century American pragmatism, in an attempt to recon-cilee the theory of knowledge with the insights from Darwin's evolutionary biology. Thus,, an alternative for Aristotle's ideal of knowledge was developed, an alterna-tivee that can do without the assumption that science needs a secure foundation inn the form of a set of evident axioms from which all truths can be deduced. It wass shown that attempts, still inspired by the demands of traditional philoso-phy,, to define the concepts of truth and reality in terms of the newly conceived belief-doubt-beliefbelief-doubt-beliefmodelmodel are, to say the least, somewhat premature. Instead, it wass proposed to focus our attention on more precise formulations of the model. Consequently,, the logical epistemology of the most prominent contemporary advocatee of the belief-doubt-beliej'model, Isaac Levi, has been expounded at length inn the third chapter. In the course of this exposition, serious drawbacks of the approachh favoured by Levi came to the fore. Levi's claims to construct a nor-mativee theory about belief change could not be substantiated, let alone that his theoryy admits an empirical test. These characteristics are unacceptable. In the facee of recent pleas, among others from naturalistic philosophers, for empirical evaluationss of philosophical theories, it was argued that the field of belief change urgentlyy needs a reformulation in order to make possible empirical assessments of thee merits of the proposed theories. A fruitful way to addres this reformulation problemm would be an approach that concentrates on eliminating parameters in theoriess about belief change which have withstood practical assessment so far. Inn the fourth chapter, this new program for the field of belief change was carriedd out in detail. First, by representing the information offered as a finite state,state, we avoided the computational problems that are posed by representations off  information by deductively closed sets of sentences. Second, rather than rely on 91 1 92 2 ChapterChapter 5. Conclusion extra-logicall  considerations in the definition of contraction, the newly proposed systemm had a purely logical contraction operator. Third, unlike the host of the systemss for belief change that have been presented in the literature, the system couldd cope with inconsistencies, which, if necessary, could be removed one by one. \Vee have not only developed techniques to change a finite state via expansion orr contraction, but have indicated methods to extract consistent 'beliefs' from inconsistentt finite states as well.1 Iss this all there is? Obviously, there is much more to belief change than avoidingg bewilderment in the presence of contradictions: Diee Anpassung der Gedanken aneinander erschöpft sich nicht in der Abschleifungg der Widersprüche. [...] Das Ökonomisieren, Harmon-isieren.. Organisieren der Gedanken, welches wir als ein biologisches Bedürfniss fühlen. geht weit über die Forderung der logischen Wider-spruchslosigkeitspruchslosigkeit hinaus. [Mach. 1905. p. 176] 5.22 Future Work Sincee the publication of Quine's programmatic 'Epistemology Naturalized' (1969), inn which Quine prompts to undertake empirical investigations into the connec-tionss between our 'theory of the world1 and our sensory stimuli,2 epistemologists havee become more and more interested in something which could be called aptly metanaturalism.metanaturalism. Rather than concentrate on the construction and evaluation off  theories about cognition, the contemporary philosophical discussion has been limitedd largely to the Kant-style question as to how, in the face of the demise of rationalisticc approaches to epistemology, a naturalistic epistemology might still bee possible. (In the meantime, cognitive psychologists, neurologists, logicians and researcherss within AI do the jobs epistemologists used to do.) Thee recent collection of essays Naturalismus (2000), edited by the German philosopherss Keil and Schnadelbach, is a case in point. In an introductory essay, thee editors addres the problem of defining the term 'naturalism', discussing sev-enteenn proposals for a definition. Koppelberg, in his contribution, makes clear thatt naturalism must not be equated to empiricism, fysicalism, scientism, or an-timentalism.. Moreover, the editors claim "dafi sich mit der Opposition gegen denn Supranaturalismus heute keine interessante Position mehr markieren lafit" lrThee extractors, which have been defined in the last section of the fourth chapter, fulfil l att least one of Nuel Belnap's wishes: "The complete reasoner should, presumably, have some strategyy for giving up part of what it believes when it finds its beliefs inconsistent. [...] I havee never heard of a practical, reasonable, mechanizable strategy for revision of belief in the presencee of contradiction" [Belnap, 1977, p. 9]. 22 "The stimulation of his sensory receptors is all the evidence anybody has had to go on. ultimately,, in arriving at his picture of the world. Why not just see how this construction really proceeds?'""  [Quine, 1969, p. 75.] 5.2.5.2. Future Work 93 3 [Keill  and Schnadelbach, 2000, p. 31]. The present thesis has shown that, although antirationalismm might not be worth the trouble of yet another philosophical de-fense,, traces of rationalistic theorizing abound in contemporary epistemology and philosophicall  logic. Byy and large, the discussion in the belief change literature has been focussed largelyy on technicalities and on a priori argumentations in favor of a specific choicee of a set of postulates. Lots of different systems have been proposed, lots off  different formal desiderata have been formulated and defended, usual on the basiss of concise, a priori argumentations, that ultimately rely on pre-theoretical intuitions.. As a starting phase, this is how it should be. It would be a mistake, however,, never to leave the formal considerations for what they are and go on too try to put the proposed systems to an empirical test. Only by testing formal belieff  change theories empirically, can convincing arguments for or against a spe-cificc approach be found, since it would not be the first time in philosophical or mathematicall  research that exclusive reliance on intuitions led us astray. After all,, unlike research in, for example, modal logic, investigations into belief change doo purport to explain some phenomena in an empirical domain. It would be a gravee mistake to conceive of belief change research as a wholly rationalistic (in thee philosophical sense of the word) matter. Thee investigations that have been conducted in the present thesis have, of course,, not been empirical. Nevertheless, they have made an empirical test pos-sible,, because of the elimination of extra-logical considerations in the definition off  contraction. Hence, the system presented in the fourth chapter ought to be seenn as an attempt to 'pragmatize' the field of belief revision,3 that is, to make thee field of belief revision more conducive to empirical considerations than sys-temss advocated by Levi, by Alchourrón, Gardenfors and Makinson, and by their sympathizers. . Thus,, instead of indulging in purely academic debates concerning the proper definitionn of naturalism, in my opinion, the spirit of the naturalized epistemology programmee is better served by a close examination of contemporary theories aboutt cognition. We should detect those elements in these theories that obstruct empiricall  ways of assessing their merits. We should reformulate theories which possess such elements in order to make empirical evaluations of them possible. Butt most of all, we should actually carry out these empirical tests and revise ourr theories according to their outcomes. In the present thesis, the first and secondd points have been put into practice. The third point, applied to the subject matterr of the present thesis, could be implemented, for instance, by the following 33 "Such a pragmatization brings an already existing theory a system - into closer contact withh the empirical world and with practical life, and this, in turn, can inspire empirical research off  different kinds, which may seem irrelevant as long as the theory (for instance, the logical system)) is presented in its original objectivistic or solipsist-subjectivistic garb. Perhaps, prag-matizingg can not be called empirical research, but we may characterize it as a proto-empirical activity.""  [Barth, 1987, p. 11 my translation; AMT.] 94 4 ChapterChapter 5. Conclusion program: : Firstt and foremost, an empirical test of the fourth chapter's system for be-lieff  change has to be carried out. In collaboration with cognitive psychologists, testt conditions must be specified in detail. Great care must be taken that the informationn offered is really considered equally trustworthy by the test subjects. Thiss can be partly realized, for instance, by making sure that the test subjects acknowledgee that the order in which the information is offered to them is wholly arbitrary.. Moreover, the information must be selected in such a way, that the testt subjects have as few preconceived opinions as possible about the relative plausibilityy of the information offered. Then, prompted by logical theory, strate-gicc questions should be asked relating to the plausibility of selected propositions. Thee test subjects should answer these questions solely on the basis of logic and thee controlled information they received previously. Next, of course, it should be checkedd whether their answers are more or less in line with the answers provided byy our system for belief change. Furthermore,, it would certainly be of interest to generalize the theory of belief changee that was presented in the fourth chapter to include not only equable reliablee sources, but sources that differ in trustworthines as well. Though such a generalizationn would hardly affect the logic of the system, it would, first, facilitate aa comparison with belief change systems in the tradition initiated by Levi and byy Alchourrón, Gardenfors and Makinson, since in such a generalized system as welll  as in traditional belief change systems, extra-logical considerations do play aa role. Second, as attributions of trustworthines do play a role in the real-life evaluationn of received information, the generalized theory purports to cover more phenomenaa than the original theory. Thee reintroduction of extra-logical elements would, however, fall short of be-ingg an advance, unless well-argued methods are set forth according to which thee relative trustworthines of the sources can be assessed. Here, philosophical, psychologicall  and economical literature on trust wil l prove relevant. Moreover, aa multi-agent perspective seems to be incumbent, since the assessment of the trustworthiness of a source does not amount to the discovery of a timeless and objectivee property, but wil l rather be the assessment of a function, that might changee over time, of experiences the assessing agent has had with this source and withh other sources as well. 

UvA-DARE is a service provided by the library of the University of Amsterdam (http://dare.uva.nl)
UvA-DARE (Digital Academic Repository)
Belief Dynamics: (Epistemo)logical Investigations
Tamminga, A.M.
Link to publication
Citation for published version (APA):
Tamminga, A. M. (2001). Belief Dynamics: (Epistemo)logical Investigations. ILLC.
General rights
It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s),
other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons).
Disclaimer/Complaints regulations
If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating
your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask
the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam,
The Netherlands. You will be contacted as soon as possible.
Download date: 04 Feb 2021
Chapterr 5 
Conclusion n 
5.11 Summary of the Results 
Thee introductory chapter served to present the belief-doubt-belief model that was 
firstfirst conceived within 19th century American pragmatism, in an attempt to recon-
cilee the theory of knowledge with the insights from Darwin's evolutionary biology. 
Thus,, an alternative for Aristotle's ideal of knowledge was developed, an alterna-
tivee that can do without the assumption that science needs a secure foundation 
inn the form of a set of evident axioms from which all truths can be deduced. It 
wass shown that attempts, still inspired by the demands of traditional philoso-
phy,, to define the concepts of truth and reality in terms of the newly conceived 
belief-doubt-beliefbelief-doubt-beliefmodelmodel are, to say the least, somewhat premature. Instead, it 
wass proposed to focus our attention on more precise formulations of the model. 
Consequently,, the logical epistemology of the most prominent contemporary 
advocatee of the belief-doubt-beliej'model, Isaac Levi, has been expounded at length 
inn the third chapter. In the course of this exposition, serious drawbacks of the 
approachh favoured by Levi came to the fore. Levi's claims to construct a nor-
mativee theory about belief change could not be substantiated, let alone that his 
theoryy admits an empirical test. These characteristics are unacceptable. In the 
facee of recent pleas, among others from naturalistic philosophers, for empirical 
evaluationss of philosophical theories, it was argued that the field of belief change 
urgentlyy needs a reformulation in order to make possible empirical assessments of 
thee merits of the proposed theories. A fruitful way to addres this reformulation 
problemm would be an approach that concentrates on eliminating parameters in 
theoriess about belief change which have withstood practical assessment so far. 
Inn the fourth chapter, this new program for the field of belief change was 
carriedd out in detail. First, by representing the information offered as a finite 
state,state, we avoided the computational problems that are posed by representations 
off  information by deductively closed sets of sentences. Second, rather than rely on 
91 1 
92 2 ChapterChapter 5. Conclusion 
extra-logicall  considerations in the definition of contraction, the newly proposed 
systemm had a purely logical contraction operator. Third, unlike the host of the 
systemss for belief change that have been presented in the literature, the system 
couldd cope with inconsistencies, which, if necessary, could be removed one by one. 
\Vee have not only developed techniques to change a finite state via expansion 
orr contraction, but have indicated methods to extract consistent 'beliefs' from 
inconsistentt finite states as well.1 
Iss this all there is? Obviously, there is much more to belief change than 
avoidingg bewilderment in the presence of contradictions: 
Diee Anpassung der Gedanken aneinander erschöpft sich nicht in der 
Abschleifungg der Widersprüche. [...] Das Ökonomisieren, Harmon-
isieren.. Organisieren der Gedanken, welches wir als ein biologisches 
Bedürfniss fühlen. geht weit über die Forderung der logischen Wider-
spruchslosigkeitspruchslosigkeit hinaus. [Mach. 1905. p. 176] 
5.22 Future Work 
Sincee the publication of Quine's programmatic 'Epistemology Naturalized' (1969), 
inn which Quine prompts to undertake empirical investigations into the connec-
tionss between our 'theory of the world1 and our sensory stimuli,2 epistemologists 
havee become more and more interested in something which could be called aptly 
metanaturalism.metanaturalism. Rather than concentrate on the construction and evaluation 
off  theories about cognition, the contemporary philosophical discussion has been 
limitedd largely to the Kant-style question as to how, in the face of the demise of 
rationalisticc approaches to epistemology, a naturalistic epistemology might still 
bee possible. (In the meantime, cognitive psychologists, neurologists, logicians and 
researcherss within AI do the jobs epistemologists used to do.) 
Thee recent collection of essays Naturalismus (2000), edited by the German 
philosopherss Keil and Schnadelbach, is a case in point. In an introductory essay, 
thee editors addres the problem of defining the term 'naturalism', discussing sev-
enteenn proposals for a definition. Koppelberg, in his contribution, makes clear 
thatt naturalism must not be equated to empiricism, fysicalism, scientism, or an-
timentalism.. Moreover, the editors claim "dafi sich mit der Opposition gegen 
denn Supranaturalismus heute keine interessante Position mehr markieren lafit" 
lrThee extractors, which have been defined in the last section of the fourth chapter, fulfil l 
att least one of Nuel Belnap's wishes: "The complete reasoner should, presumably, have some 
strategyy for giving up part of what it believes when it finds its beliefs inconsistent. [...] I 
havee never heard of a practical, reasonable, mechanizable strategy for revision of belief in the 
presencee of contradiction" [Belnap, 1977, p. 9]. 
22 "The stimulation of his sensory receptors is all the evidence anybody has had to go on. 
ultimately,, in arriving at his picture of the world. Why not just see how this construction really 
proceeds?'""  [Quine, 1969, p. 75.] 
5.2.5.2. Future Work 93 3 
[Keill  and Schnadelbach, 2000, p. 31]. The present thesis has shown that, although 
antirationalismm might not be worth the trouble of yet another philosophical de-
fense,, traces of rationalistic theorizing abound in contemporary epistemology and 
philosophicall  logic. 
Byy and large, the discussion in the belief change literature has been focussed 
largelyy on technicalities and on a priori argumentations in favor of a specific 
choicee of a set of postulates. Lots of different systems have been proposed, lots 
off  different formal desiderata have been formulated and defended, usual on the 
basiss of concise, a priori argumentations, that ultimately rely on pre-theoretical 
intuitions.. As a starting phase, this is how it should be. It would be a mistake, 
however,, never to leave the formal considerations for what they are and go on 
too try to put the proposed systems to an empirical test. Only by testing formal 
belieff  change theories empirically, can convincing arguments for or against a spe-
cificc approach be found, since it would not be the first time in philosophical or 
mathematicall  research that exclusive reliance on intuitions led us astray. After 
all,, unlike research in, for example, modal logic, investigations into belief change 
doo purport to explain some phenomena in an empirical domain. It would be a 
gravee mistake to conceive of belief change research as a wholly rationalistic (in 
thee philosophical sense of the word) matter. 
Thee investigations that have been conducted in the present thesis have, of 
course,, not been empirical. Nevertheless, they have made an empirical test pos-
sible,, because of the elimination of extra-logical considerations in the definition 
off  contraction. Hence, the system presented in the fourth chapter ought to be 
seenn as an attempt to 'pragmatize' the field of belief revision,3 that is, to make 
thee field of belief revision more conducive to empirical considerations than sys-
temss advocated by Levi, by Alchourrón, Gardenfors and Makinson, and by their 
sympathizers. . 
Thus,, instead of indulging in purely academic debates concerning the proper 
definitionn of naturalism, in my opinion, the spirit of the naturalized epistemology 
programmee is better served by a close examination of contemporary theories 
aboutt cognition. We should detect those elements in these theories that obstruct 
empiricall  ways of assessing their merits. We should reformulate theories which 
possess such elements in order to make empirical evaluations of them possible. 
Butt most of all, we should actually carry out these empirical tests and revise 
ourr theories according to their outcomes. In the present thesis, the first and 
secondd points have been put into practice. The third point, applied to the subject 
matterr of the present thesis, could be implemented, for instance, by the following 
33 "Such a pragmatization brings an already existing theory a system - into closer contact 
withh the empirical world and with practical life, and this, in turn, can inspire empirical research 
off  different kinds, which may seem irrelevant as long as the theory (for instance, the logical 
system)) is presented in its original objectivistic or solipsist-subjectivistic garb. Perhaps, prag-
matizingg can not be called empirical research, but we may characterize it as a proto-empirical 
activity.""  [Barth, 1987, p. 11 my translation; AMT.] 
94 4 ChapterChapter 5. Conclusion 
program: : 
Firstt and foremost, an empirical test of the fourth chapter's system for be-
lieff  change has to be carried out. In collaboration with cognitive psychologists, 
testt conditions must be specified in detail. Great care must be taken that the 
informationn offered is really considered equally trustworthy by the test subjects. 
Thiss can be partly realized, for instance, by making sure that the test subjects 
acknowledgee that the order in which the information is offered to them is wholly 
arbitrary.. Moreover, the information must be selected in such a way, that the 
testt subjects have as few preconceived opinions as possible about the relative 
plausibilityy of the information offered. Then, prompted by logical theory, strate-
gicc questions should be asked relating to the plausibility of selected propositions. 
Thee test subjects should answer these questions solely on the basis of logic and 
thee controlled information they received previously. Next, of course, it should be 
checkedd whether their answers are more or less in line with the answers provided 
byy our system for belief change. 
Furthermore,, it would certainly be of interest to generalize the theory of belief 
changee that was presented in the fourth chapter to include not only equable 
reliablee sources, but sources that differ in trustworthines as well. Though such a 
generalizationn would hardly affect the logic of the system, it would, first, facilitate 
aa comparison with belief change systems in the tradition initiated by Levi and 
byy Alchourrón, Gardenfors and Makinson, since in such a generalized system as 
welll  as in traditional belief change systems, extra-logical considerations do play 
aa role. Second, as attributions of trustworthines do play a role in the real-life 
evaluationn of received information, the generalized theory purports to cover more 
phenomenaa than the original theory. 
Thee reintroduction of extra-logical elements would, however, fall short of be-
ingg an advance, unless well-argued methods are set forth according to which 
thee relative trustworthines of the sources can be assessed. Here, philosophical, 
psychologicall  and economical literature on trust wil l prove relevant. Moreover, 
aa multi-agent perspective seems to be incumbent, since the assessment of the 
trustworthiness of a source does not amount to the discovery of a timeless and 
objectivee property, but wil l rather be the assessment of a function, that might 
changee over time, of experiences the assessing agent has had with this source and 
withh other sources as well. 


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Belief Dynamics: (Epistemo)logical Investigations
Tamminga, A.M.
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Tamminga, A. M. (2001). Belief Dynamics: (Epistemo)logical Investigations. ILLC.
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Download date: 08 Feb 2021
Chapterr 5 
Conclusion n 
5.11 Summary of the Results 
Thee introductory chapter served to present the belief-doubt-belief model that was 
firstfirst conceived within 19th century American pragmatism, in an attempt to recon-
cilee the theory of knowledge with the insights from Darwin's evolutionary biology. 
Thus,, an alternative for Aristotle's ideal of knowledge was developed, an alterna-
tivee that can do without the assumption that science needs a secure foundation 
inn the form of a set of evident axioms from which all truths can be deduced. It 
wass shown that attempts, still inspired by the demands of traditional philoso-
phy,, to define the concepts of truth and reality in terms of the newly conceived 
belief-doubt-beliefbelief-doubt-beliefmodelmodel are, to say the least, somewhat premature. Instead, it 
wass proposed to focus our attention on more precise formulations of the model. 
Consequently,, the logical epistemology of the most prominent contemporary 
advocatee of the belief-doubt-beliej'model, Isaac Levi, has been expounded at length 
inn the third chapter. In the course of this exposition, serious drawbacks of the 
approachh favoured by Levi came to the fore. Levi's claims to construct a nor-
mativee theory about belief change could not be substantiated, let alone that his 
theoryy admits an empirical test. These characteristics are unacceptable. In the 
facee of recent pleas, among others from naturalistic philosophers, for empirical 
evaluationss of philosophical theories, it was argued that the field of belief change 
urgentlyy needs a reformulation in order to make possible empirical assessments of 
thee merits of the proposed theories. A fruitful way to addres this reformulation 
problemm would be an approach that concentrates on eliminating parameters in 
theoriess about belief change which have withstood practical assessment so far. 
Inn the fourth chapter, this new program for the field of belief change was 
carriedd out in detail. First, by representing the information offered as a finite 
state,state, we avoided the computational problems that are posed by representations 
off  information by deductively closed sets of sentences. Second, rather than rely on 
91 1 
92 2 ChapterChapter 5. Conclusion 
extra-logicall  considerations in the definition of contraction, the newly proposed 
systemm had a purely logical contraction operator. Third, unlike the host of the 
systemss for belief change that have been presented in the literature, the system 
couldd cope with inconsistencies, which, if necessary, could be removed one by one. 
\Vee have not only developed techniques to change a finite state via expansion 
orr contraction, but have indicated methods to extract consistent 'beliefs' from 
inconsistentt finite states as well.1 
Iss this all there is? Obviously, there is much more to belief change than 
avoidingg bewilderment in the presence of contradictions: 
Diee Anpassung der Gedanken aneinander erschöpft sich nicht in der 
Abschleifungg der Widersprüche. [...] Das Ökonomisieren, Harmon-
isieren.. Organisieren der Gedanken, welches wir als ein biologisches 
Bedürfniss fühlen. geht weit über die Forderung der logischen Wider-
spruchslosigkeitspruchslosigkeit hinaus. [Mach. 1905. p. 176] 
5.22 Future Work 
Sincee the publication of Quine's programmatic 'Epistemology Naturalized' (1969), 
inn which Quine prompts to undertake empirical investigations into the connec-
tionss between our 'theory of the world1 and our sensory stimuli,2 epistemologists 
havee become more and more interested in something which could be called aptly 
metanaturalism.metanaturalism. Rather than concentrate on the construction and evaluation 
off  theories about cognition, the contemporary philosophical discussion has been 
limitedd largely to the Kant-style question as to how, in the face of the demise of 
rationalisticc approaches to epistemology, a naturalistic epistemology might still 
bee possible. (In the meantime, cognitive psychologists, neurologists, logicians and 
researcherss within AI do the jobs epistemologists used to do.) 
Thee recent collection of essays Naturalismus (2000), edited by the German 
philosopherss Keil and Schnadelbach, is a case in point. In an introductory essay, 
thee editors addres the problem of defining the term 'naturalism', discussing sev-
enteenn proposals for a definition. Koppelberg, in his contribution, makes clear 
thatt naturalism must not be equated to empiricism, fysicalism, scientism, or an-
timentalism.. Moreover, the editors claim "dafi sich mit der Opposition gegen 
denn Supranaturalismus heute keine interessante Position mehr markieren lafit" 
lrThee extractors, which have been defined in the last section of the fourth chapter, fulfil l 
att least one of Nuel Belnap's wishes: "The complete reasoner should, presumably, have some 
strategyy for giving up part of what it believes when it finds its beliefs inconsistent. [...] I 
havee never heard of a practical, reasonable, mechanizable strategy for revision of belief in the 
presencee of contradiction" [Belnap, 1977, p. 9]. 
22 "The stimulation of his sensory receptors is all the evidence anybody has had to go on. 
ultimately,, in arriving at his picture of the world. Why not just see how this construction really 
proceeds?'""  [Quine, 1969, p. 75.] 
5.2.5.2. Future Work 93 3 
[Keill  and Schnadelbach, 2000, p. 31]. The present thesis has shown that, although 
antirationalismm might not be worth the trouble of yet another philosophical de-
fense,, traces of rationalistic theorizing abound in contemporary epistemology and 
philosophicall  logic. 
Byy and large, the discussion in the belief change literature has been focussed 
largelyy on technicalities and on a priori argumentations in favor of a specific 
choicee of a set of postulates. Lots of different systems have been proposed, lots 
off  different formal desiderata have been formulated and defended, usual on the 
basiss of concise, a priori argumentations, that ultimately rely on pre-theoretical 
intuitions.. As a starting phase, this is how it should be. It would be a mistake, 
however,, never to leave the formal considerations for what they are and go on 
too try to put the proposed systems to an empirical test. Only by testing formal 
belieff  change theories empirically, can convincing arguments for or against a spe-
cificc approach be found, since it would not be the first time in philosophical or 
mathematicall  research that exclusive reliance on intuitions led us astray. After 
all,, unlike research in, for example, modal logic, investigations into belief change 
doo purport to explain some phenomena in an empirical domain. It would be a 
gravee mistake to conceive of belief change research as a wholly rationalistic (in 
thee philosophical sense of the word) matter. 
Thee investigations that have been conducted in the present thesis have, of 
course,, not been empirical. Nevertheless, they have made an empirical test pos-
sible,, because of the elimination of extra-logical considerations in the definition 
off  contraction. Hence, the system presented in the fourth chapter ought to be 
seenn as an attempt to 'pragmatize' the field of belief revision,3 that is, to make 
thee field of belief revision more conducive to empirical considerations than sys-
temss advocated by Levi, by Alchourrón, Gardenfors and Makinson, and by their 
sympathizers. . 
Thus,, instead of indulging in purely academic debates concerning the proper 
definitionn of naturalism, in my opinion, the spirit of the naturalized epistemology 
programmee is better served by a close examination of contemporary theories 
aboutt cognition. We should detect those elements in these theories that obstruct 
empiricall  ways of assessing their merits. We should reformulate theories which 
possess such elements in order to make empirical evaluations of them possible. 
Butt most of all, we should actually carry out these empirical tests and revise 
ourr theories according to their outcomes. In the present thesis, the first and 
secondd points have been put into practice. The third point, applied to the subject 
matterr of the present thesis, could be implemented, for instance, by the following 
33 "Such a pragmatization brings an already existing theory a system - into closer contact 
withh the empirical world and with practical life, and this, in turn, can inspire empirical research 
off  different kinds, which may seem irrelevant as long as the theory (for instance, the logical 
system)) is presented in its original objectivistic or solipsist-subjectivistic garb. Perhaps, prag-
matizingg can not be called empirical research, but we may characterize it as a proto-empirical 
activity.""  [Barth, 1987, p. 11 my translation; AMT.] 
94 4 ChapterChapter 5. Conclusion 
program: : 
Firstt and foremost, an empirical test of the fourth chapter's system for be-
lieff  change has to be carried out. In collaboration with cognitive psychologists, 
testt conditions must be specified in detail. Great care must be taken that the 
informationn offered is really considered equally trustworthy by the test subjects. 
Thiss can be partly realized, for instance, by making sure that the test subjects 
acknowledgee that the order in which the information is offered to them is wholly 
arbitrary.. Moreover, the information must be selected in such a way, that the 
testt subjects have as few preconceived opinions as possible about the relative 
plausibilityy of the information offered. Then, prompted by logical theory, strate-
gicc questions should be asked relating to the plausibility of selected propositions. 
Thee test subjects should answer these questions solely on the basis of logic and 
thee controlled information they received previously. Next, of course, it should be 
checkedd whether their answers are more or less in line with the answers provided 
byy our system for belief change. 
Furthermore,, it would certainly be of interest to generalize the theory of belief 
changee that was presented in the fourth chapter to include not only equable 
reliablee sources, but sources that differ in trustworthines as well. Though such a 
generalizationn would hardly affect the logic of the system, it would, first, facilitate 
aa comparison with belief change systems in the tradition initiated by Levi and 
byy Alchourrón, Gardenfors and Makinson, since in such a generalized system as 
welll  as in traditional belief change systems, extra-logical considerations do play 
aa role. Second, as attributions of trustworthines do play a role in the real-life 
evaluationn of received information, the generalized theory purports to cover more 
phenomenaa than the original theory. 
Thee reintroduction of extra-logical elements would, however, fall short of be-
ingg an advance, unless well-argued methods are set forth according to which 
thee relative trustworthines of the sources can be assessed. Here, philosophical, 
psychologicall  and economical literature on trust wil l prove relevant. Moreover, 
aa multi-agent perspective seems to be incumbent, since the assessment of the 
trustworthiness of a source does not amount to the discovery of a timeless and 
objectivee property, but wil l rather be the assessment of a function, that might 
changee over time, of experiences the assessing agent has had with this source and 
withh other sources as well. 


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