Online research in philosophy

In 'Axiological Actualism' Josh Parsons attempts to defend both the intuition that the anticipated welfare of a person cannot constitute a reason to bring him or her into being and the intuition that such considerations can constitute a reason not to . The former, 'basic' intuition he defends by an appeal to the belief that 'ethical theory should refrain from assigning levels of welfare or anything of the sort to merely possible people'. The latter, 'converse' intuition he defends by an appeal to prudential considerations. I argue that Parsons's attempts to defend these intuitions are unpersuasive. On the one hand, and notwithstanding his attempts to demonstrate the contrary, the basic intuition is undermined by the claim that an actual person could have been worse off if she had never existed. On the other, his grounding of the converse intuition in prudential considerations runs counter to the ought implies can dictum and is also highly counterintuitive.

In Mathematical Thought and Its Objects, Charles Parsons examines the notion of object, with the aim to navigate between nominalism, denying that distinctively mathematical objects exist, and forms of Platonism that postulate a transcendent realm of such objects. He introduces the central mathematical notion of structure and defends a version of the structuralist view of mathematical objects, according to which their existence is relative to a structure and they have no more of a “nature” than that confers on them.

Mathematical apriorists sometimes hold that our non-derived mathematical beliefs are warranted by mathematical intuition. Against this, Philip Kitcher has argued that if we had the experience of encountering mathematical experts who insisted that an intuition-produced belief was mistaken, this would undermine that belief. Since this would be a case of experience undermining the warrant provided by intuition, such warrant cannot be a priori. I argue that this leaves untouched a conception of intuition as merely an aspect of our ordinary ability to reason. Thus the apriorist may still hold that some mathematical beliefs are warranted by intuition. I would like to thank an anonymous referee for Philosophia Mathematica and an audience at the Spring 2006 Long Island Philosophy Society/New Jersey Regional Philosophical Association conference for helpful comments.

What is perception doing in mathematical reasoning? To address this question, I discuss the role of perception in geometric reasoning. Perception of the shape properties of concrete diagrams provides, I argue, a surrogate consciousness of the shape properties of the abstract geometric objects depicted in the diagrams. Some of what perception is not doing in mathematical reasoning is also discussed. I take issue with both Parsons and Maddy. Parsons claims that we perceive a certain type of abstract object. Maddy claims (at least at one time claimed) that perception provides the basis for intuition of mathematical sets. 1 Mathematical reasoning with diagrams 2 Do we perceive abstract objects? 3 Do we perceive mathematical sets?

In this article, I will discuss the relationship between mathematical intuition and mathematical visualization. I will argue that in order to investigate this relationship, it is necessary to consider mathematical activity as a complex phenomenon, which involves many different cognitive resources. I will focus on two kinds of danger in recurring to visualization and I will show that they are not a good reason to conclude that visualization is not reliable, if we consider its use in mathematical practice. Then, I will give an example of mathematical reasoning with a figure, and show that both visualization and intuition are involved. I claim that mathematical intuition depends on background knowledge and expertise, and that it allows to see the generality of the conclusions obtained by means of visualization.

This collection of new essays offers a 'state-of-the-art' conspectus of major trends in the philosophy of logic and philosophy of mathematics. A distinguished group of philosophers addresses issues at the centre of contemporary debate: semantic and set-theoretic paradoxes, the set/class distinction, foundations of set theory, mathematical intuition and many others. The volume includes Hilary Putnam's 1995 Alfred Tarski lectures, published here for the first time.

Charles Parsons’ book “Mathematical Thought and Its Objects” of 2008 (Cambridge University Press, New York) is critically discussed by concentrating on one of Parsons’ main themes: the role of intuition in our understanding of arithmetic (“intuition” in the specific sense of Kant and Hilbert). Parsons argues for a version of structuralism which is restricted by the condition that some paradigmatic structure should be presented that makes clear the actual existence of structures of the necessary sort. Parsons’ paradigmatic structure is the so-called ‘intuitive model’ of arithmetic realized by Hilbert’s strings of strokes. This paper argues that Hilbert’s strings, considered as given in intuition, cannot play the role Parsons assigns to them: the criteria of identity of these strings do not have the sharpness that Parsons wants to see in them, and Parsons inadvertently projects abstract structures into his ‘intuitive model’. This diagnosis is exemplified with respect to (a) Parsons’ distinction between addition and multiplication on the one hand and exponentiation on the other and (b) his analysis of arithmetical knowledge in simple cases like “7 + 5 = 12”. All in all, it is claimed that Parsons book contains many important insights with respect to, for example, different versions structuralism, the notion of “natural number” and its uniqueness, induction, predicativity and other things, for which he is rightly famous, but that his way of drawing on the notion of intuition leaves too many questions unanswered.

This article discusses Charles Parsons' conception of mathematical intuition. Intuition, for Parsons, involves seeing-as: in seeing the sequences III and III as the same type, one intuits the type. The type is abstract, but intuiting the type is supposed to be epistemically analogous to ordinary perception of physical objects. And some non-trivial mathematical knowledge is supposed to be intuitable in this way, again in a way analogous to ordinary perceptual knowledge. In particular, the successor axioms are supposed to be knowable intuitively. This conception has the resources to respond to some familiar objections to mathematical intuition. But the analogy to ordinary perception is weaker than it looks, and the warrant provided for non-trivial mathematical beliefs by intuition of this sort is weak-too weak, perhaps, to yield any mathematical knowledge.