The development of symbolic logic is often presented in terms of a cumulative story of consecutive innovations that led to what is known as modern logic. This narrative hides the difficulties that this new logic faced at first, which shaped its history. Indeed, negative reactions to the emergence of the new logic in the second half of the nineteenth century were numerous and we study here one case, namely logic at Oxford, where one finds Lewis Carroll, a mathematical teacher who (...) promoted symbolic logic, and John Cook Wilson, the Wykeham Professor of Logic who notoriously opposed it. An analysis of their disputes on the topic of logical symbolism shows that their opposition was not as sharp as it might look at first, as Cook Wilson was not so much opposed to the « symbolic » character of logic, but the intrusion of mathematics and what he perceived to be the futility of some of its problems, for logicians and philosophers alike. (shrink)

According to the traditional view, the following incompatibility holds true: in reasoning, either there is warrant (certainty) or there is novelty. If there is warrant, there is not novelty: that would be the case of deductive reasoning. If there is novelty, there is not warrant: that would be the case of inductive reasoning. Causal reasoning would belong to the second group because there is novelty and, therefore, there is not warrant in it. I argue that this is false: reasoning may (...) have novelty and, nevertheless, be a deductive one. That is precisely what happens in (some) causal reasoning. And I will develop the following line of argumentation: one thing is to warrant that some state of affairs exists and other thing is to warrant that warrant. So we may have correct deductive reasoning without having certainty of that correction, like in some cases of causal reasoning. (shrink)

The following paper deals with the notion of existence, especially as concerns natural languages. In Section 1, starting from some quite obvious examples drawn from logic, I sketch the problem of the existential presupposition usually ascribed to noun phrases. My opinion is that the point of view frequently adopted in this case is unduly restrictive, for the existence which is believed to be presupposed here is actual existence. Accordingly, I emphasize the need for having a weaker notion of existential presupposition, (...) such that the existence (if this word can still be used) here referred to is relevant only to linguistic goals. Section 2 sketches this notion, by assimilating existence (in the weak sense) to identification in a linguistic space. (I deal here only with intuitive considerations: a more formal account will be given, I hope, in another paper.) Finally, in Section 3, the notion of actual existence is examined by contrast with the linguistic (or weak) notion of existence: and this is a question which of course can't be tackled in terms of a purely linguistic analysis, for it needs a general, epistemo-logical approach. (shrink)

We propose a reconstruction of the constellation of problems and philosophical positions on the nature and number of the primitives of logic in four authors of the nineteenth century logical scene: Peano, Padoa, Frege and Peirce. We argue that the proposed reconstruction forces us to recognize that it is in at least four different senses that a notation can be said to be simpler than another, and we trace the origins of these four senses in the writings of these authors. (...) We conclude that Frege, and even more so Peirce, developed new notations not to make drawing logical conclusions easier but in order to answer the needs of logical analysis. (shrink)