Memory Disjunctivism: a Causal Theory

Relationalists about episodic memory must endorse a disjunctivist theory of memory-experience according to which cases of genuine memory and cases of total confabulation involve distinct kinds of mental event with different natures. This paper is concerned with a pair of arguments against this view, which are analogues of the ‘causal argument’ and the ‘screening off argument’ that have been pressed in recent literature against relationalist (and hence disjunctivist) theories of perception. The central claim to be advanced is that to deal with these two arguments, memory disjunctivists both can and should draw on resources that are standardly appealed to by rival common factor theories of episodic memory, and, in particular, to the idea that genuine memories and merely apparent ones are to be distinguished, at least in part, in terms of the distinctive ways in which they are caused. On the proposed view, there are substantive causal constraints associated both with cases of genuine memory and with cases of mere confabulation. The resulting theory thus tells us something important about the nature both of genuine memories and of mere confabulations, namely, that such experiences must be caused in certain distinctive ways and cannot occur except as the result of a distinctive sort of causal process. In addition, the theory enables the disjunctivist to offer a unified response to an important pair of arguments against her view.

Screening off generalized: Reichenbach’s legacy

Eells and Sober proved in 1983 that screening off is a sufficient condition for the transitivity of probabilistic causality, and in 2003 Shogenji noted that the same goes for probabilistic support. We start this paper by conjecturing that Hans Reichenbach may have been aware of this fact. Then we consider the work of Suppes and Roche, who demonstrated in 1986 and 2012 respectively that screening off can be generalized, while still being sufficient for transitivity. We point out an interesting difference between Reichenbach’s screening off and the generalized version, which we illustrate with an example about haemophilia among the descendants of Queen Victoria. Finally, we embark on a further generalization: we develop a still weaker condition, one that can be made as weak as one wishes.

A New Condition for Transitivity of Probabilistic Support

As is well known, implication is transitive but probabilistic support is not. Eells and Sober, followed by Shogenji, showed that screening off is a sufficient constraint for the transitivity of probabilistic support. Moreover, this screening off condition can be weakened without sacrificing transitivity, as was demonstrated by Suppes and later by Roche. In this paper we introduce an even weaker sufficient condition for the transitivity of probabilistic support, in fact one that can be made as weak as one wishes. We explain that this condition has an interesting property: it shows that transitivity is retained even though the Simpson paradox reigns. We further show that by adding a certain restriction the condition can be turned into one that is both sufficient and necessary for transitivity.

Computational Modeling of Backwards-Blocking Reasoning in Human Adults

Causal reasoning is a fundamental cognitive ability that enables humans to learn about the complex interactions in the world around them. However, it remains unknown whether causal reasoning is underpinned by a Bayesian mechanism or an associative one. For example, some maintain that a Bayesian mechanism underpins human causal reasoning because it can better account for backward-blocking (BB) and indirect screening-off (IS) findings than certain associative models. However, the evidence is mixed about the extent to which learners engage in both kinds of reasoning. Here, we report an experiment and several computational models that examine to what extent adults engage in BB and IS reasoning using the blicket-detector design. The results revealed that adults’ causal ratings in a backwards-blocking and indirect screening-off condition were consistent with associative rather than a Bayesian computational model. These results are interpreted to mean that adults use associative processes to reason about causal events.

STRUCTURAL AND OPTICAL PROPERTIES OF CADMIUM SULFIDE NANOPARTICLES PREPARED BY PRECIPITATION METHOD

Cadmium Sulfide nanoparticles were prepared by a simple and cost effective precipitation method. Xray analysis revealed broad diffraction peaks indicating that the particles are of very small size. The prominent broad peaks at 2θ values of 26.48°, 43.90°, and 51.91°, which could be indexed to the (002), (110) and (112) direction of the hexagonal phase of CdS. Optical studies showed maximum absorbance in the UV region but minimum absorbance in the VIS-NIR regions make it an excellent material for screening off UV portion of electromagnetic spectrum in UV filters and sensors.

Defeaters and Disqualifiers

Justification depends on context: even if E on its own justifies H, still it might fail to justify in the context of D. This sort of effect, epistemologists think, is due to defeaters, which undermine or rebut a would-be justifier. I argue that there is another fundamental sort of contextual feature, disqualification, which doesn't involve rebuttal or undercutting, and which cannot be reduced to any notion of screening-off. A disqualifier makes some would-be justifier otiose, as direct testimony sometimes does to distal testimony, and as manifestly decisive evidence might do to gratuitous evidence on the same team. Basing a belief on disqualified evidence, moreover, is distinctively irrational. One is not necessarily irresponsible. Instead one is turning down a free upgrade to a sleeker, stabler basis for one's beliefs. Such an upgrade would prevent wastes of epistemic effort, since someone who bases her belief on a disqualified proposition E will need to remember E and rethink her belief should E ever be defeated. The upgrade might also reduce reliance on unwieldy evidence, if E is relevant only thanks to some labyrinthine argument; and if even ideal agents should doubt their ability to follow such arguments, even they should care about disqualifiers.

A PUZZLE ABOUT EXPERTS, EVIDENTIAL SCREENING-OFF AND CONDITIONALIZATION

ABSTRACTI present a puzzle about the epistemic role beliefs about experts' beliefs play in a rational agent's system of beliefs. It is shown that accepting the claim that an expert's degree of belief in a proposition, A, screens off the evidential support another proposition, B, gives to A in case the expert knows and is certain about whether B is true, leads in some cases to highly unintuitive conclusions. I suggest a solution to the puzzle according to which evidential screening off is rejected, but show that the price of this solution is either giving up on the mere idea of deferring to expert's opinion or giving up on Bayesian conditionalization.

O pewnym założeniu twierdzenia Bella

Dowód twierdzenia Bella sprowadza się do wyprowadzenia którejś z nierówności Bella. W ich standardowych wyprowadzeniach jednak kluczową rolę odgrywa warunek faktoryzowalności łącznego prawdopodobieństwa warunkowego, który można uzyskać jako konsekwencję dwóch innych warunków, znanych jako parameter independence i outcome independence. Pierwszy z nich jest dość oczywistym wyrazem warunku lokalności, natomiast drugi budzi wątpliwości. Ponieważ jednak jest on uszczegółowieniem warunku screening off zasady wspólnej przyczyny, jego podważenie wymagałoby zakwestionowania również tego warunku. Gdyby się to powiodło, efektywny dowód twierdzenia Bella wymagałby wyprowadzenia nierówności Bella nie wykorzystującego żadnego uszczegółowienia warunku screening off. Przestawiona zostanie sugestia kierunku, w jakim powinny iść poszukiwania modelu naruszającego ten warunek.