Commonsense ontology often conflicts with the ontology of our best scientific and philosophical theories. However, commonsense ontology, and commonsense belief systems in general, seems to be remarkably efficient and cognitively fundamental. In cases of contrast, it is better to find a way to reconcile commonsense and “theoretical” ontologies. Given that commonsense ontologies are typically expressed within natural language, a classical procedure of reconciliation is semantical. The strategy is that of individuating the “ontologically problematic” expressions of natural language and paraphrasing the sentences in which they appear in a (formal) language whose commitments are compatible with those of our best theories. We believe that this strategy of reconciliation, though quite standard, especially in the philosophical literature, is problematic: for a start, it forces us to conclude that the “real content” of our commonsense expressions and beliefs is different from what it appears. Commonsense ontology becomes just an illusion. We will thus propose an alternative approach: according to our view, a commonsense ontology is reconciled with a theoretical ontology in case it is shown that the explanation of why we believe in the existence of a problematic entity is compatible with our best theories. We will call this kind of reconciliation “epistemic”. The advantage of an epistemic reconciliation is that commonsense ontology is treated in its own right and could be taken prima facie. Another advantage of the view is that epistemic reconciliation can be analysed through the notion of explaining away: a commonsense ontology is epistemically reconciled with a theoretical ontology if and only if the problematic entities of the commonsense ontology are explained away by “respectable” entities of the theoretical ontology. In the final part of the paper, we sketch a formal analysis of explaining away.

Abstract In a computational program there can be two kinds of errors: (i) critical errors and (ii) non-critical errors. A critical error stops the program in a global way, which means the error cannot be fixed in the subsequent computation process. A non-critical error partially stops the computation program, and the error can be fixed in the subsequent computation process. We argue that two kinds of errors correspond to two kinds of suspension and can be modeled using Paraconsistent Weak Kleene ($ {\textsf{PWK}}$) belief revision theory, with the help of a new interpretation of the third value of $ {\textsf{PWK}}$, that is, off-topic. According to this new interpretation, if a proposition obtains the third value $\textbf{u}$, it means it is off-topic. Within our framework of $ {\textsf{PWK}}$ belief revision theory, we will show that a non-critical error corresponds to a non-critical suspension and that a critical error corresponds to a critical suspension.

We reconsider Dalla Pozza and Garola's pragmatic interpretation of intuitionistic logic regarded as a logic of assertions and their justifications and its relations with classical logic. We recall an extension of this approach to a logic dealing with assertions and obligations , related by a notion of causal implication developed especially by K. Ranalter. We focus on the extension to co-intuitionistic logic , seen as a logic of hypotheses in work by G. Bellin and others and on polarized bi-intuitionistic logic as a logic of assertions and hypotheses: looking at the S4 modal translation, we consider variants of the system AHL of bi-intuitionistic logic to represent the duality between the intuitionistic and the co-intuitionistic fragments, correcting and improving on the previous treatment. A computational interpretation of co-intuitionism as a distributed calculus of coroutines is then used to give an operational interpretation of subtraction. Work on linear co-intuitionism is then recalled, a linear calculus of co-intuitionistic coroutines which was used by Bellin to give a categorical model of co-intuitionistic linear logic, and also a probabilistic interpretation of linear co-intuitionism. Also we remark that by extending the language of intuitionistic logic we can express the notion of expectation , an assertion that in all situations the truth ofpis possible and that in a logic of expectations the law of double negation holds. Similarly, extending co-intuitionistic logic, we can express the notion of conjecture thatp , defined as a hypothesis that in some situation the truth ofpis epistemically necessary . to Carlo Dalla Pozza (1942–2014)

In this paper we focus on a specific aspect of the notion of conceptualisation, i.e. on the issue of the specification of a certain kind of concept: sortal concept. Our starting point is the intuitive idea that a sortal concept cannot be specified in isolation from a general notion of entity. We think that this idea has some bearing on the way in which identity criteria should be conceived, since they are usually taken as a fundamental tool for the specification of a sortal concept. The first goal of our paper is to discuss and point out some difficulties concerning the relation between sortals and identity criteria. In general, we think that the specification of a sortal presupposes - in Russellian terms - a range of significance on which the concept is defined. It follows that the sortal cannot be stated without a specification of its range of significance. This means that identity criteria for a sortal K providing conditions of identity only for objects falling under K are not enough to specify K. Independently of this point, we are quite skeptical about the possibility of achieving a formal satisfactory definition of sortal. We will try to show that even Guarino and Welty's last proposal [4] does not succeed. Our second goal concerns which concepts are to be taken as sortals. By thinking that identity criteria are necessary and sufficient conditions for identity, Guarino and Welty cannot accept that, say, a is S1 and a is S2, in the case that S1 and S2 are associated with incompatible criteria. So they are lead to postulate, for example, that not a but b is S2 and a is constituted by b. We defend the thesis that it is possible to take some concepts - in our case S2 - as endowed only with necessary conditions for identity. We will argue for some specific choices.