The ArgumentIn this paper, I argue that the most significant contribution of the Jesuits to early modern science consists in the introduction of a new “image of knowledge.”In contradistinction to traditional Scholasticism, this image of knowledge allows for the possibility of a science of hypothetical entities.This problem became crucial in two specific areas. In astronomy, knowledge of mathematical entities of unclear ontological status was nevertheless proclaimed certain. In theology, God's knowledge of the future acts of man, logically considered as future (...) contingents, was also proclaimed certain. In both cases the concept of certain knowledge of hypothetical entities was problematic and challenged a central premise of the accepted canons of logic, i.e., that the objects of true knowledge must be real objects.The main argument of this paper is that the practical orientation of the Jesuit cultural milieu enabled Jesuit scientists and theologians to ignore accepted logical considerations and to modify traditional Thomist images of knowledge. Nevertheless, this modification was not so radical as to change the contemporary organization of knowledge. This was due to the peculiar status of the Jesuits within the church establishment, which exposed them to harsh criticism and created a deep need for legitimation. Thus, the limitations of Jesuit scientific culture are accounted for in institutional, rather than in logical terms. (shrink)

The problem analysed in this paper is whether we can gain knowledge by using valid inferences, and how we can explain this process from a model-theoretic perspective. According to the paradox of inference (Cohen & Nagel 1936/1998, 173), it is logically impossible for an inference to be both valid and its conclusion to possess novelty with respect to the premises. I argue in this paper that valid inference has an epistemic significance, i.e., it can be used by an agent to (...) enlarge his knowledge, and this significance can be accounted in model-theoretic terms. I will argue first that the paradox is based on an equivocation, namely, it arises because logical containment, i.e., logical implication, is identified with epistemological containment, i.e., the knowledge of the premises entails the knowledge of the conclusion. Second, I will argue that a truth-conditional theory of meaning has the necessary resources to explain the epistemic significance of valid inferences. I will explain this epistemic significance starting from Carnap’s semantic theory of meaning and Tarski’s notion of satisfaction. In this way I will counter (Prawitz 2012b)’s claim that a truth-conditional theory of meaning is not able to account the legitimacy of valid inferences, i.e., their epistemic significance. (shrink)

1. This paper addresses the development of mutual relations between two sets of ideas in scholastic logic. First, consider the following statements: (1) It is impossible to encounter a chimera.(2)...

In his review of my Prelude to Galileo, Ernan McMullin rejects my emendation of Pierre Duhem's “continuity thesis” wherein I develop the case for a pronounced medieval-scholastic influence on Galileo's science based on parallels between Galileo's early Latin compositions and lectures given by contemporary Jesuits at the Collegio Romano. He does so on two grounds: that the evidence of derivation I provide, using textual parallels, is so strong that it refutes the claim for any intellectual influence, being a better instance (...) of mindless copying than one of personal appropriation; and that, in any event, the logical structure of the argument which I attribute to Galileo's mature work is not that of demonstration ex suppositione as understood by Aquinas, and so the example I provide of Galileo's use of suppositio “does not link him in any significant way to the specifically Thomist tradition of natural science”. An adequate reply to this critique would require the introduction of more historical evidence than would be appropriate for the pages of this journal. A few remarks, however, may be in order concerning such evidence which bears directly on McMullin's first ground, and concerning the implications of this evidence for contemporary philosophy of science, which bear on his second. (shrink)