"A metatudomany hatarai es Godel inkomplettsegi tetelei" Az eloadas celja a 20. szazadi elmeletfelfogasok (szintaktikai, szemantikai es strukturalista) rovid bemutatasa, es a rajuk tamaszkodo fobb tudomanyelmeleti es tudomanyfilozofiai kerdesfeltevesek es valaszok elemzese. Ennek reszekent megvizsgaljuk a Church-fele eldonthetetlensegi tetel es Godel inkomplettsegi teteleinek hagyomanyos ertelmezeset. Az eloadas vitatemaja a hatarteteleknek az elmeletek nyelvi reprezentaciojanak modszerere alapozott uj interpretacioja.
Giovanni Boniolo Istituto di Filosofia, Universita di Padova
MODELS, FICTIONS AND COUNTERFACTUALS Someone could consider the topic of the models only an "old hat". Right in this way, someone could have thought after the analyses by R. Carnap, G. Hempel, E. Nagel, R. Braithwaite. But the criticisms by Hesse, Achinstein and Spector, and the proposals by Hesse herself and Black have shown that much more could be said; as, in these years, Redhead and Cartwright have pointed out, too. Each interpretation is a new point of view and each point of view permits to see new aspects, as Popper underlines. The interpretative way I will propose, based on fictions, a la H.Vaihinger, is different from both the semantical one and Hesse's analogical one. For this reason it should throw light on aspects till now neglected or considered insignificant. Nevertheless, the principal goal of my discussion will not be an attempt to give an entirely new theory of the models, but to insert a fictionalistic theory of them in a more general framework which deals with the counterfactuals, too. Obviously, this fact does not mean that I disregard the results achieved by the previous interpretations, specially by the analogical one.
Michael Stoelzner Institute Vienna Circle, Vienna, Austria
LEVELS OF PHYSICAL THEORIES The most sublime task of physics is often seen in presenting, some day, a world formula or a simple Theory of Everything (T.O.E.) that crowns the top of a pyramid of physical laws. This view has been propagated by many high energy physicists, particu- larly by Steven Weinberg. If one examines in how far the candi- dates for that claim determine the scenario on lower levels, quite often cases appear, in which more depends on the actual circumstances (initial conditions or constants of nature) than can be deduced from the higher, more general theory. I will argue that laws on lower levels might have been present on higher lev- els merely as possibilities. Symmetry breakings, which determined the actual values of constants of nature, could have occured spontaneously in the course of the evolution of the universe. Such a view attributes to the physical laws at each particular level the genuine importance they deserve. Philosophically it considers the explanation of a given physical phenomenon as the primary quest in physics. In the cases men- tioned the deductions performable fail to give a sufficient ex- planation. The understanding of a physical theory is maximal if it can be comprehended as part of a hierarchy of physical theories. I propose not to base the level structure of physics in a foggy objective reductionism, but to view it as an interplay between two elements. Firstly, in the mathematical formulation of physics a natural layering is automatically given. This order es- tablished between general concepts and specific situations is, however, only local and does not induce an entire pyramid of mathematics. But secondly, the levels established that way only become physical theories if one supplements the specific physicsl circumstances at the particular level, for instance the results of unpredictable phase transitions and fundamental constants. Both elments serve two possible simplicity criteria, axiomatic and relational (from propositions to phenomena) simplicity.
Alberto Zanardo Department of Mathematics, University of Padova, Italy
BRANCHING-TIME SEMANTICS FOR TEMPORAL LOGICS The basic idea underlying branching-time logic is that, in general, every moment in time has only one past, but many possible futures. This leads to pictureing time as a tree or as a set of linear orders (possible histories, possible courses of affairs) which bear some connection to each other. In the logic of linear time, the Prior operators P (it was the case that) and F (it will be the case that) are generally interpreted in a standard Kripke fashion. In a branching-time context, instead, these operators can be interpreted in various different ways and it is often meaningful to consider other temporal or modal operators and to combine them with the Priorean ones. Moreover, if the interpretation of these operators is meant to support a branching-time semantics for propositional temporal languages, there are different options also for the evaluation of propositional variables. For this reason, there are various branching-time semantics for temporal languages. In the talk, these semantics will be discussed and compared both from the point of view of model theory and from the point of view of their adequacy to specify the meaning of tensed expressions in natural languages.
PLEH CSABA ELTE BTK Altalanos Pszichologia Tanszek
"Tiszta megismeres" es erdek: A megismeres funkcionalista pszichologiaja es a tudomany onallosaga Az eloadas kindulopontja az a vita, amely a mai kognitiv pszichologiaban es kognitiv tudomanyban szembeallitja egymassal azon felfogasokat, amelyek a megismeres vilagat az "elvont", "tiszta" reprezentaciok vilaganak tartjak, s amelyek minden kognitiv teljesitmenynek kozvetlenul "haszon erteket" tulajdonitanak. Ket peldan fogom illusztralni a szembenallast: (1) Az eszleles modularista felfogasa szemben a tapasztalat es "erdek" fuggo perceptualis elkepzelesekkel. (Hogyan jelenik meg az onmagukba zart modulok tetelezese mint a "veridikus" tukrozes biztositeka?) (2) A nyelv keletkezesenek es hasznalatanak "mellektermek elvu", reprezentacios felfogasa, szemben az "adaptacios" es kommunikacios felfogasokkal. Az eloadas megprobal kiterni arra, mifele altalanosabb tanulsagokat hordoznak ezek a vitak a kovetkezo harom atfogo kerdesre nezve: (i) mi lehet biztos kiindulasi pont a megismeresben? (ii) milyen kettos kihatasa van az evolucios gondolkodasnak a mai kognitiv gondolkodasra nezve? Hogyan lehet mindket tabor evolucios? (iii) hogyan bomlik fel ketfele hozzaallasra a klasszikus funkcionalista pszichologiai orokseg a mai "szellemi vilagban"?
Roman R. Zapatrin Department of Mathematics, St. Petersbourg
LOGIC PROGRAMMING AS QUANTUM MEASUREMENT The emphasis is made on the juxtaposition of (quantum theorem) proving versus quantum (theorem proving). The logical contents of verification of the statements concerning quantum systems is outlined. The Zittereingang (trembling input) principle is introduced to enhance the resolution of predicate satisfiability problem provided the processor is in a position to perform operations with continuous input. A realization of Zittereingang machine by a quantum system is suggested.
Redei Miklos
"Neumann-halok es a logikai fuggetlenseg problemai" A Neumann-algebra es Neumann-halo fogalmainak folelevenitese utan azt a problemat vizsgaljuk, mikor tekintheto egy Neumann halo ket reszhaloja - mint kvantumlogika - logikai ertelemben fuggetlennek. Egy termeszetes fuggetlenseg definicio es a logikai fuggetlenseg problemajanak motivalasa utan allitasokat fogalmazunk, melyek a logikai fuggetlenseget kapcsolatba hozzak mas, statisztikus fuggetlensegi tulajdonsagokkal.
Szabo Laszlo ELTE TTK Elmeleti Fizika Tanszek
Az elagazo teridok elmelete es a Greenberger-Horne-Zeilinger-tetel Egyik kiindulopontunk Nuel Belnap elagazo terido elmelete. Ez az egyetlen olyan szigoruan megfogalmazott formalis elmelet, amely lehetove teszi az objectiv indeterminizmus koncepciojanak es a relativitaselmeletnek az egyesiteset. Ha igaz a kvantumelmelet kovetkeztetese, melyszerint a vilagunkban letezik objektiv -- vagyis nem csupan a tudasunk hianyara visszavezetheto -- modalitas (indeterminisztikussag), akkor a vilagunk modalis strukturajat egy nem-trivialis elagazo terido irja le, vagyis olyan, amelyben nem csak egyetlen ag van. Az eloadas masik pillere a Greenberger, Horne es Zeilinger (GHZ) altal 1990-ben bebizonyitott kvantummechanikai tetel, amely egyfajta Bell-tetel, valoszinusegekre felirt egyenlotlensegek nelkul. A bizonyitasnak azonban vannak gyengesegei, amelyeket tobben, igy Bohm es Hiley is kritizaltak. Az elagazo terido elmelet nyelvet felhasznalva sikerult Belnappal megadnunk a GHZ-tetel egy precizebb ujrafogalmazasat. Ebben az uj megfogalmazasban sikerult olyan bizonyitast adnunk, amely mentes a kritizalt gyengesegektol. A problema altalunk megadott analizisebol az is vilagosan kiderul, hogy hol vannak a GHZ-tetel ervenyessegenek pontos hatarai.
Abstract This paper traces the 'Institutional' turn in the philosophy of science to the failure of classical foundationalism on the one hand, and to the failure to distinguish between Descartes' methodological scepticism and his rench epistemology' on the other. In so doing, it argues that the institutional approach leads to authoritarianism, since it retains the structure and function of classical foundationalism while leaving the oundations' themselves floating in midair. And it suggests that a better response would be to maintain Descartes' resolution to doubt whatever can be doubted without contradiction, while renouncing his resolution not to accept any thesis or belief that has not been proven. Az eloadas idotartama 50-60 perc, amelyet rovid szunet utan kb. 30-60 perc vita kovet. Az eloadas anyaga (Word 6.0 v. PostScript) elerheto a tanszeki home page-en: ftp://hps.elte.hu/pub/Papers/notturno.doc
ftp://hps.elte.hu/pub/Papers/notturno.ps Idopont: 1997 februar 27., csutortok, 18.00 ora Hely: Budapesti Müszaki Egyetem Tanári Klubja, K. ep. I. em. Az eloadasra a Magyar Filozofiai Tarsasag Tudomanyfilozofia Szakosztalya, a BME Filozofia Tanszeke es az ELTE TTK Tudomanytortenet es Tudomanyfilozofia Tanszeke kozos szervezeseben kerul sor. Minden erdeklodot szeretettel varnak a szervezok.