[T]his collection is rich in both historical detail and philosophical ideas, living up to Sieg's exhortations for philosophy of mathematics to integrate conceptual, technical, and historical aspects into its perspective.
Oran Magal, Philosophia Mathematica
Anyone who has at least a passing interest in the philosophy of mathematics, the relatively recent history of mathematics, mathematical logic (especially proof theory), the growth of ideas in mathematics, or the foundations of mathematics, will find this essential reading. Sieg is a major scholar in all of these areas, and he has shown, throughout his career, how work in any of these areas illuminates all of them.
Stewart Shapiro, Notre Dame Philosophical Reviews