(Ph.D., Stanford University). His interests lie in the philosophy of mathematics and its history, in philosophy of logic, and in mathematical logic. His written work is currently focused upon the philosophy of mathematical practice, including mathematical explanation, mathematical style, diagrammatic reasoning and visualization in mathematics, and purity of methods. In this area, he has recently published "The Philosophy of Mathematical Practice"(OUP 2008). He has also recently completed a book on 20th-century explorations of the foundations of mathematics. The book is titled "The Adventure of Reason" (Oxford University Press, 2010).