|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Is it possible to give a justification of our own practice of deductive inference? The purpose of this paper is to explain what such a justification might consist in and what its purpose could be. On the conception that we are going to pursue, to give a justification for a deductive practice means to explain in terms of an intuitively satisfactory notion of validity why the inferences that conform to the practice coincide with the valid ones. That is, a justification should provide an analysis of the notion of validity and show that the inferences that conform to the practice are just the ones that are valid. Moreover, a complete justification should also explain the purpose, or point, of our inferential practice. We are first going to discuss the objection that any justification of our deductive practice must use deduction and therefore be circular. Then we will consider a particular model of justificatory explanation, building on Kreisel’s concept of informal rigour. Finally, in the main part of the paper, we will discuss three ideas for defining the notion of validity: (i) the classical conception according to which the notion of (bivalent) truth is taken as basic and validity is defined in terms of the preservation of truth; (ii) the constructivist idea of starting instead with the notion of (a canonical) proof (or verification) and define validity in terms of this notion; (iii) the idea of taking the notions of rational acceptance and rejection as given and define an argument to be valid just in case it is irrational to simultaneously accept its premises and reject its conclusion (or conclusions, if we allow for multiple conclusions). Building on work by Dana Scott, we show that the last conception may be viewed as being, in a certain sense, equivalent to the first one. Finally, we discuss the so-called paradox of inference and the informativeness of deductive arguments..
|
|
|
|
|
|
|
|
|
Since neither a human mind nor a computer can deal directly with infinite structures, well-behaved models of belief change should operate exclusively on belief states that have a finite representation. Three ways to achieve this without resorting to a finite language are investigated: belief bases, specified meet contraction, and focused propositional extenders. Close connections are shown to hold between the three approaches.
Keywords: finitude, finiteness, belief change, belief base, specified meet contraction, sentential selector, propositional extender, Grove spheres
|
|
|
|
|
|
|
|
|
|
|
|
|
The logical empiricists in Vienna and their Swedish counterparts in Uppsala shared a scientific ethos that underlined the philosophical academics as representatives for universalism, disinterest, professional loyalty, organized scepticism and public interest. Rudolf Carnap, Axel Hägerström and Ingemar Hedenius regarded themselves as intellectuals, offering their philosophical tools to society. However, when the scientific ethos was articulated by Robert Merton in 1942, the circumstances had drastically changed. The European tradition was left behind. However, the claim is that neither the professionalism, nor the specialized epistemology in analytical philosophy necessarily alienated the philosopher from the public. The gap occurred when the epistemology ceased to be cultural meaningful, as a part of the spirit of the time. The modernistic spirit promoted the ethos of intellectuality. In the 1960s a new ethos took over: the philosophers as purely academic professional experts, in US and Sweden.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|