As you will doubtless have guessed from the title of this chapter, I am going to talk about my philosophical career as a whole (up to the ninth decade, anyway). The “Back Again,” by the way, does not mean I have abandoned my interest in ethics! Not at all. Rather it refers to the fact that in December 2005 I published a paper titled “A Philosopher Looks at Quantum Mechanics (Again)” (Putnam 2005). I could also have titled these reflections, “From Philosophy of Mathematics to Ethics and Back Again,” since I recently delivered a lecture titled “Indispensability Arguments in the Philosophy of Mathematics.”2