In this paper, I defend the contingency view on the laws of nature: laws of nature hold in metaphysically contingent way. First, I present an argument to demonstrate that categorical properties exist, and point out that the contingency view follows if we accept the existence of categorical properties. Second, through the critical examination of the view that laws of nature hold in metaphysically necessary way, I point out that we should take the conceivability into consideration in deciding the range of possibility and hence we should accept the contingency view. Third, I argue that this paper's approach to appeal to the conceivability mitigate the severity of a problem with categorical properties, that is, a problem of quiddity. Finally, I argue the philosophical implication of the contingency view in relation to contemporary Humeanism. In my view, though it may sound strange, those who support contemporary Humean metaphysics should take a rationalistic stance.

By applying the extended system of modal logic developed in [32], we present a logical analysis of the Gettier problem. Based on the result, in particular, we clarify the following point. In the literature on the Gettier problem, most authors seem to share the opinion that in general ‘belief’ precedes ‘knowledge’: we believe a proposition while we do not necessarily believe ourselves to have known it to be true. Interestingly, our analysis suggests that the story is the other way round in a sense: in general, for some proposition p, we believe that we have known that p, then we believe that p. Accordingly, even if given some reason for wanting to believe that p, we usually do not have the bare belief that p. Instead, in such a situation, more deliberately we think that it might be that p, or it can be hypothesized that p. Then, we can say, what we have at the start is not the bare belief that p, but “might possibility” or “hypothetical possibility” that p, which presumably involves abductive reasoning.

Hardy presented a famous argument that shows that there exist no hidden variables in quantum mechanics. His argument is called Hardy's paradox. The commentaries and discussions on Hardy's paradox have been ordinarily presented for deterministic hidden variables, and it has not been discussed whether a similar paradox will occurs in probabilistic hidden variables. So, first, I will show that Hardy's argument can also be applied to probabilistic hidden variables. After that, I discuss the common cause of a correlation, which has been actively discussed in the philosophy of science in recent years. That is because requiring the common cause of a quantum correlation is mathematically equivalent to introducing a probabilistic hidden variable to explain the correlation. Some researchers argued that in the non-existence proof of hidden variables, the existence of a common common-cause to multiple correlations is tacitly assumed, however that is unreasonably strong. According to their idea, it is sufficient if there exists a respective common-cause of each correlation. However, it will be revealed that at least as far as Hardy's paradox is concerned, merely weakening the common common-cause requirement to the respective common-cause requirement does not help to construct a local model.

In The Aporia of Mind: Space, Body and Meaning, Noya tried to answer two difficult philosophical problems about the world and other minds. And his answers were given mainly by the elimination of person from his theory of Cyoubou. In this paper, I examine his arguments and explain why sceptics would not be fully satisfied with his solution. First, I argue that the explanation of the unity of multimodal perceptions should require person. Second, I insist that person is needed for the individualization of the body and show that the subject of experiences can be separated from that of acts. Finally, after showing the difference between actuality and reality, I point that Noya's theory missed the problem of the other lives in the different actuality.