In his paper "Explaining Deductive Inference" Prawitz states what he calls «a fundamental problem of logic and the philosophy of logic»: the problem of explaining «Why do certain inferences have the epistemic power to confer evidence on the conclusion when applied to premisses for which there is evidence already?». In this paper I suggest a way of articulating, and partly modifying, the intuitionistic answer to this problem in such a way as to both answer Prawitz's problem and satisfy a requirement I argue to be crucial for any epistemic theory of the meaning of the logical constants: the requirement that evidence is epistemically transparent.

This article aims to the logical development of a practical and applicable analysis model of argumentative transparency, specifically for the study of public policies. To this end, we draw upon a “political concept of transparency” which redefines pragmatic logic operations in contexts of trust and cooperation between actors. The model combines a principal-agent framework, non-linear assumptions of production of information, and conversational maxims of use of language. This results in an analysis that is focused on the actors’ capacity and their relation. The model also finds a necessary link between active and passive transparency processes, where the building of trust arising from transparency is directly associated with the reduction of control costs. In addition, this article intends to be an applied model, with visual tools related to transparent decision-making processes, protocols for marking up transparency in texts and, finally, an empirical analysis of transparency in the argument of specific public policies. The combination of multiple frameworks and the deduction of a logical model presents an original work for the study of public policies.

A new language for epistemic logic is introduced in which the epistemic operators are of the form | x : x_1.... x_n | with the intended reading "x knows of x_1 .... x_n that ...''. Analogously we can express "t knows of t_1 .... t_n that ... '', where t, t_1.... t_n are terms. An advantage of this approach is that we can quantify on the agents, "every y knows of x_1.... x_n that A'' or "some expert knows of t_1.... t_n that A'' can easily be expressed. The semantics we present for this language is a generalization of the transition semantics, called "epistemic transition semantics" in which the possible worlds are states of affairs compatible with the epistemic state of some agent. A calculus is presented and shown to be complete with respect to epistemic transition semantics.

Modal logic S5 is commonly viewed as an epistemic logic that captures the most basic properties of knowledge. Kripke proved a completeness theorem for the first-order modal logic S5 with respect to a possible worlds semantics. A multiagent version of the propositional S5 as well as a version of the propositional S5 that describes properties of distributed knowledge in multiagent systems has also been previously studied. This article proposes a version of S5-like epistemic logic of distributed knowledge with quantifiers ranging over the set of agents, and proves its soundness and completeness with respect to a Kripke semantics.