ELTE TTK Tudomanytortenet es Tudomanyfilozofia Tanszek Budapest, Pazmany P. setany 1/A Tudomanyfilozofia Szeminarium ________________________________________________ 1999. Szeptember 27. (hetfo !) 12:30 6. em. 661. B a r r y L o e w e r Rutgers University Collegium Budapest PROBABILITY AND DETERMINISM Although probability is essential to the formulation (and evaluation) of scientific theories and although a great deal is known about how to employ probabilistic concepts, there is still philosophical controversy concerning the nature of probability. Some hold that only probability concerns only degrees of belief (either subjective or constrained by "objective" rules) while others hold that it concerns mind-independent features of reality. The latter view divides among those who hold that it concerns only frequencies (actual or hypothetical) and those who hold that it concerns a "causal propensity." The nature of probability is especially puzzling when the underlying dynamics is completely deterministic as in classical mechanics and Bohm's version of quantum mechanics. Some claim that when the dynamics is deterministic then all objective probabilities are 1 or 0. But this seems at odd with the scientific practice. In my talk I will review some of the main ideas concerning the nature of probability and also an idea suggested by David Lewis. According to Lewis probability concerns an objective feature of reality that supervenes on the totality of propositions not concerning chance. Whether or not Lewis' account is correct for dynamical chances I argue that it provides a good account of chance statements when the dynamics are deterministic. 1999. oktober 4. (hetfo) 12:30 6. em. 661. T o m a s z P l a c e k Department of Philosophy, Jagiellonian University, Cracow OUTCOMES IN BRANCHING SPACE-TIME (OBST) -AN ANALYSIS OF BELL'S THEOREM- The framework of BRANCHING SPACE-TIME (BST; cf. Belnap 1992, SYNTHESE 92, pp. 385--434) has recently been extended to allow for the introduction of outcomes of events and the analysis of GHZ theorems. (Kowalski & Placek, forthcoming in BRIT. J. PHIL. SCI. and INT. J. THEOR. PHYS.) In BST, space-time and modality are incorporated in the very structure of the models, which consist of a pair $\langle W, \leq \rangle$, where $W$ is a non-empty set weakly ordered by $\leq$, which is interpreted as `causally accessible from.' Maximal upward directed subsets of $W$ are called `histories,' and proper subsets of histories are called `events.' Two events are called `space-like separated' if neither causally precedes the other. `Atomic outcomes' of an event $E$ are those parts of the event's causal future that split in $E$. The main result of Kowalski & Placek is that the family of outcomes of an event forms a Boolean algebra. The paper also proves that in GHZ setups, there is always a common cause (CC) in the sense of Reichenbach if directions are held fixed, but that there is no single COMMOM common cause (cf. Hofer-Szabo et al., forthcoming in BRIT. J. PHIL. SCI.) accounting for the outcomes of incompatible settings. For an analysis of Bell's theorem, I assign probabilities to outcomes by imposing a classical probability measure on the Boolean algebra of the outcomes of each given event. In the derivation of Bell's theorem, I use probability measures of the form $p_{L\alpha \cup R\beta}(Lx \cap Ry)$, $x,y \in \{+,-\}$, where the subscript indicates that the result is an outcome of the event of measuring the spin projections along directions $\alpha$ on the left and $\beta$ on the right. Probabilities for single results on the left or on the right are calculated from these measures, allowing us to express correlations as $p_{L\alpha \cup R\beta}(Lx \cap Ry) \neq p_{L\alpha \cup R\beta}(Lx) \times p_{L\alpha \cup R\beta}(Ry)$. Since correlations between space-like separated results appear disturbing, it is natural to look for an explanation in terms of a CC located in the results' common past. The CC's outcomes divide histories in such a way that actual runs of a correlation experiment are seen as belonging to two or more varieties differentiated by hidden factors. You may think of these hidden factors as restoring the deterministic order. You may also be more modest and require only that the hidden factors restore the causal order, i.e., that in each sub-population, the correlations disappear. Formally, for space-like separated events $E$ and $F$ with correlated outcomes $e$ and $f$, respectively, a CC is an event C preceding both $e$ and $f$, such that for every atomic outcome $\omega_{i}$ of $C$, $$ p_{E\cup F\cup C}(e \cap f|\omega_{i}) = p_{E\cup F\cup C}(e |\omega_{i}) \times p_{E \cup F\cup C}(f|\omega_{i})$$, where $p_{E \cup F \cup C}$ is defined on the enlarged probability space. Now, for any correlated pair $e,f$, we CAN construct mathematically an enlarged probability space containing such a CC. Moreover, for any finite number of correlations we CAN construct a single large probability space containing a set of distinct CCs, each CC taking care of one correlation. However, in the Bell/Clauser-Horne argument, one wants something more: one postulates a single common CC accounting for all the correlated outcomes of $L\alpha\cup R\beta$, $L\alpha\cup R\beta--\prime$, $L\alpha--\prime\cup R\beta$, and $L\alpha--\prime\cup R\beta--\prime$. Given the standard assumptions of locality and `no conspiracy,' which in our framework take the form \begin{equation*} \begin{split} & \forall \alpha, \beta, \varphi, x p_{L\alpha \cup R\beta\cup C}(Lx) = p_{L\alpha \cup R\varphi\cup C}(Lx)\ & \forall \alpha, \beta, \gamma, y p_{L\alpha \cup R\beta\cup C}(Ry) = p_{L\gamma \cup R\beta\cup C}(Ry) \end{split} \tag{LOCALITY} \end{equation*} \begin{equation*} \forall \alpha, \beta, \gamma, \varphi, i p_{L\alpha \cup R\beta\cup C}(\omega_i) = p_{L\gamma \cup R\varphi\cup C}(\omega_i), \tag{NO CONSPIRACY} \end{equation*} we derive the Bell/CH inequalities, which are empirically violated. Thus, there cannot be a common common cause accounting for the Bell/CH correlations. 1999. oktober 11. (hetfo) 12:30 6. em. 661. E. S z a b o L a s z l o ELTE, MTA Elmeleti Fizikai Kutato Csoport ELTE, Tudomanytortenet es Tudomanyfilozofia Tanszek EINSTEIN MEGOLDOTTA AZ EPR-BELL PARADOXONT? Úgy tunik igen, sot meg egy sereg mas problemajat a kvantumelmeletnek. "Prizma-modell" neven Arthur Fine 1982-ben egy olyan megoldast javasolt az EPR-Bell problemara, es altalaban a kvantummechanika lokalis-realista interpretaciojara, amelyrol, mint kesobb o maga kideritette, mar Einstein is emlitest tett egy 1936-os cikkeben, illetve nehany Rosenhez es Schrodingerhez irt leveleben. E megoldas nem kapott kulonosebb visszhangot, sot maga Fine sem vette igazan komolyan, hiszen kesobbi cikkeiben úgy ir a Bell-tetelrol, mintha az Einstein-Fine-interpretacio nem is letezne. Ennek oka, hogy tevesen, Fine ezt a megoldast a valosagban vegrehajtott kiserletekben hasznalt detektorok nem 100%-os hatasfokaval hozta kapcsolatba. Az eloadasban az Einstein-Fine-interpretaciot egy új megvilagitasban mutatom be. Megmutatom, hogy semmi koze nincs a detektorok hatasfokanak sokat diszkutalt problemajahoz. A valosagban elvegzett EPR-Bell kiserletek elemzesevel megmutatom, hogy e kiserletek logikai szerkezetuknel fogva teljesen kompatibilisek az Einstein-Fine-interpretacioval, amely viszont tokeletesen feloldja az EPR-Bell paradoxont. 1999. oktober 18. (hetfo) 12:30 6. em. 661. K a t a l i n B a l o g Yale University CONCEIVABILITY, POSSIBILITY AND THE MIND-BODY PROBLEM I want to take on the question of what a class of arguments, usually called the Conceivability Arguments, have to say about the mind-body problem. These arguments have two different versions. In one version, considerations of conceivability are taken to support the claim that phenomenal consciousness is not identical, realized by, or supervenient on, physical properties (for example, Kripke 1972, 140-162, Nagel 1974, Robinson 1993, White 1986, Jackson 1998, and Chalmers 1996). According to the other version, there is an explanatory gap between phenomenal and physical levels of description, that does not exist with respect to other higher level descriptions, and that may have metaphysical ramifications. (This argument is formulated by Joseph Levine 1998, although he is himself hesitant to accept the conclusion.) My claim is that these arguments do not succeed in establishing their conclusions. That is because, and I take this to be the primary lesson of the Conceivability Arguments, what they reveal does not have to do with phenomenal consciousness itself, it rather has to do with the nature of phenomenal concepts. In the paper, I will focus on the most elaborate and sophisticated version of the Conceivability Argument for dualism. I first provide a general exposition of the structure of Conceivability Arguments, then I proceed to describe in greater detail Frank Jackson's and David Chalmers' new Conceivability Argument. Finally I construct a reductio that at the same time reveals where the arguments went wrong. 1999. oktober 25. (hetfo) 12:30 6. em. 661. K o v a c s G y u l a SZOTE, Elettani Intezet OUR BRAIN AND OUR MIND The neuronal bases of consciousness (Az eloadas magyarul lesz!) 1. Introduction 1.1. Definition of awareness & consciousness for the non-philosopher 1.2. "Components" of consciousness 1.3. Levels of human consciousness, coma, sleep, awake states 1.4. "Prerequisites" of consciousness 2. Recent results on the brain and mind problem 2.1. Visual consciousness 2.2. Blindsight 2.3. Perception vs. action 2.4. Bistable percepts 2.4.1. Ambiguous figures 2.4.2. Binocular rivalry 2.5. Electrical brain stimulation and conscious behavior 2.6. Subliminal and supraliminal stimulus processing 2.7. Time scale of consciousness Humans & Monkeys: 2.8. NCC - Neural Correlate of Consciousness Theories & models -- Laszlo E. Szabo Department of Theoretical Physics Department of History and Philosophy of Science Eotvos University, Budapest H-1518 Budapest, Pf. 32. Phone: (36-1)2090-555/6671 Fax: (36-1)372-2509 Home: (36-1)200-7318 http://hps.elte.hu/~leszabo