Many contemporary logicians acknowledge a plurality of logical theories and accept that theory choice is in part motivated by evidence. However, just as there no agreement on theories, also consensus what constitutes In this paper, I outline Jean Piaget’s psychological reasoning show how he used it to diagnose solve one the paradoxes material implication. assess use psychology source evidence f...

The topic of the void was of significant philosophical and scientific importance in the ancient and medieval world. Some, such as the atomists, maintained that the void was essential if one were to explain motion. Others, such as Aristotle, argued that the existence of the void would absolutely preclude the possibility of motion. Moreover, there were disputes concerning even how to characterize...

In epistemic logic, some axioms dealing with the notion of knowledge are rather convoluted and difficult to interpret intuitively, even though some of them, such as the axioms .2 and .3, are considered to be key axioms by some epistemic logicians. We show that they can be characterized in terms of understandable interaction axioms relating knowledge and belief or knowledge and conditional belie...

In his “Time and Modality”, based on own philosophical motivations, Arthur Norman Prior proposed the modal logic Q as a correct in 1957. developed order to offer for contingent beings, which one could rationally state that some beings are necessary. One may say is an actualist with natural semantics. This review article description/discussion of/on “The System Q” fifth chapter of Modality”. I h...

Agent programming languages based on the Belief, Desire and Intentions (BDI) framework present some interesting challenges for logicians. While BDI logics have been studied extensively, problems related to belief update and analysis of plans in BDI agent programming languages have received less attention.

Work on how to axiomatize the subtheories of first-order theory in which only a proper subset of their extra-logical vocabulary is being used led to a theorem on recursive axiomatizability and to an interpolation theorem for first-order logic. There were some fortuitous events and several logicians played a helpful role.