CAPEワークショップ(Dr. Kasaki & Dr. Szmuc)のお知らせ


日時:2017年3月24日(金), 16:00–19:30
場所:京都大学 文学部校舎1階 会議室
Masashi Kasaki (Nagoya University, Osaka University)
Damian Szmuc (University of Buenos Aires, CONICET)
16:00–17:30: Damian Szmuc “Paraconsistent logics, Meta-paraconsistent logics and beyond”
17:30–17:45: Break
17:45–19:15: Masashi Kasaki “How Many Cartesian Skepticisms?


This paper discusses paraconsistent logics, paracomplete logics, connexive logics and logics of formal inconsistency which deserve to be called that way not because of the properties they exhibit at the inferential level, but at the meta-inferential level. To achieve this goal, we use the framework of abstract consequence relations, due to Blok and Jonson. In doing so, we draw some connections between many-valued non-classical logics (as conceived by Bochvar, Hallden, Da Costa, Priest, Kleene, Dunn and Belnap), on the one hand, and q-matrices and p-matrices (as conceived by Malinowski and Frankowski), on the other. This brings the opportunity to talk about what relates logical many-valuedness and inferential many-valuedness (as conceived by Wansing and Shramko). Finally, it also suggests the reasonability of asking, yet again, what exactly a logical system is.
Cartesian skepticism appeals to a skeptical hypothesis and makes a case for the claim that S does not know that the skeptical hypothesis is false. The claim, then, constitutes an important premise of the argument for the skeptical conclusion that S does not know most, if not all, of ordinary empirical propositions. Some argues that there are two radically different versions of Cartesian skepticism, depending on what skeptical hypothesis is at stake. One version of Cartesian skepticism invokes the brain in a vat hypothesis or the evil genius hypothesis, and the other version does the dreaming hypothesis. There are several ways of demarcating these two kinds of skeptical hypotheses. First, unlike the brain in a vat hypothesis and the evil genius hypothesis, the dreaming hypothesis is compatible with the truth of ordinary empirical propositions. Second, while the possibilities envisioned in the brain in a vat hypothesis and the evil genius hypothesis are esoteric and far-fetched, those in the dreaming hypothesis are not. Third, it is even easier to establish as a genuine metaphysical possibility the dreaming hypothesis than the brain in a vat hypothesis or the evil genius hypothesis. 

Each of the three ways of demarcating the two kings of skeptical hypotheses entails that certain solutions to the skepticism with the brain in a vat hypothesis or the evil genius hypothesis won’t
work for the skepticism with the dreaming hypothesis. If the first way is correct, the denial of closure cannot be marshalled against the skepticism with the dreaming hypothesis. If the second way is correct, the safety-based response to the skepticism with the brain in a vat hypothesis or the evil genius hypothesis does not fare well with the skepticism with the dreaming hypothesis. And yet, if the third way is correct, it is difficult to dispel the dreaming hypothesis as metaphysically impossible.

In this paper, I will argue that the three ways of differentiating between the two kinds of skeptical hypotheses are not well-grounded. Notice that even the brain in a vat hypothesis is compatible with, or even strongly, cannot contradict certain ordinary empirical propositions, such as there are computers, there are scientists, there are brains, and so on. On the other hand, the dreaming hypothesis includes some true ordinary empirical propositions. Once the brain in a vat hypothesis is set up so as to include little true ordinary propositions, there is no reason to differentiate between the brain in a vat hypothesis and the dreaming hypothesis, and hence the first way fails. The same can be said of the relationship between the evil genius hypothesis and the dreaming
hypothesis. Indeed, if the dreaming hypothesis includes less true ordinary propositions, then the possible worlds in which it is true are more distant from the actual world. Thus, the second way also fails. The same consideration is advanced against the third way. If my arguments are correct, one needs no distinct response to the skepticism with the dreaming hypothesis. Good news!