Ten most influential books
See: Tyler Cowen, Will Wilkinson, Russell Arben Fox, Bryan Caplan,Matt Yglesias, and more. Haven't we done this on Facebook at some point?
I'm unsurprised by how alien Russell's and Bryan's lists are to me (in almost-opposite directions, of course). By contrast, even where my list doesn't overlap with Will's, for the most part I can recognize and to some degree share his reactions.
But, man, Rand and Nietzsche are showing up a lot, even on lists where I wouldn't expect them to. Neither's ever had a moment of hold on my mind. A friend in grad school thought that there was something odd and revealing about my complete lack of connection to Nietzsche: "You've never had a Nietzschean moment?" he asked-- a moment when I got it. Nope.
Anyway, I'll take the "formative influences" tack: books I first read before I graduated from college. And I'll arbitrarily stick to nonfiction in my general fields of professional inquiry.
1) Milton and Rose Friedman, Free to Choose. An adult friend gave this to me when I was 11 or so (and when it was very new-- the copy of it, which I still have, is in hardcover). So for me, the exposure to libertarianism and to social science/ social analysis and to serious nonfiction that contained ideas that could really give my brain exercise were simultaneous. It's hard to know what the counterfactual looks like-- how differently I would think if I hadn't read this, then. The friend said that he gave it to me because it was already clear that I would appreciate it-- that it reflected rather than (only) shaping my intellectual tastes. In any case, the ideas of regulatory capture and unintended consequences were among the first serious ideas about social analysis I ever encountered-- and the simplified moral-political philosophy of the introduction to the book genuinely inspired me.
2) John Stuart Mill, On Liberty. Read when I had just turned 16, during slow periods and coffee and lunch breaks at my summer supermarket job. (I think this is the moment when lots of smart teenagers encounter Rand or Nietzsche-- when they're looking for something to read to keep their brains going while they're off school, especially if they're in the kinds of summer jobs working/ lower middle class kids get rather than internships and the like.) It wasn't technically my first primary text in political philosophy; by then I had read Thoreau's "Resistance," a couple of the Federalist Papers, and smatterings of Plato, Smith, and Marx in my Great Books collection. But it was "On Liberty" that really fired me up about great works in political philosophy. I agreed with its conclusions, of course, but I already knew enough to know that there were things to worry about/ argue with; I wasn't excited primarily by the agreement. I was excited by the prose, the power of the arguments, and the sense of what it could be to assemble normative arguments about big questions.
3) Bernard Bailyn, Ideological Origins of the American Revolution. Read about the same time: the first work of scholarship I ever read, and still one of my favorites.
4) Leonard Levy, Original Intent and the Framers' Constitution. The second work of scholarship I ever read. The overarching argument of the book was a little beyond my reach at the time, but the detailed legal-historical analysis of the various constitutional provisions greatly impressed me, and complemented what I had learned about the era from Bailyn.
5) John Rawls, A Theory of Justice. First read it my first semester of college; it aggravated me and annoyed me and in many ways defined the intellectual world I've lived in ever since.
6) Michael Walzer, Spheres of Justice. Spheres annoyed me even more, the first two times I read it, and not in the same "I must engage with and respond to this" way that Rawls did. First two times I read it, I didn't see the point of it; by comparison with Rawls (or Nozick), Walzer never seemed to have any arguments. Eventually, as I followed the path I now understand as leading from political philosophy to political theory, I came to see Spheres of Justice as a wise and profound book, and an important exemplar of how to think normatively but not abstractly. There's still almost no argument in it I find compelling, nothing that I'm brought to agree with by Walzer's reasoning. But I do love to reread from it, when the occasion presents itself.
7) F.A. Hayek, The Constitution of Liberty and Law, Legislation, and Liberty, vol. 1 (Listed together because I really think they belong together-- I think LLL v1 completes the argument of Constitution and makes the earlier book much more satisfying than it is on its own.) First read Hayek in a freshman seminar taught by by university's president on the history of liberalism. (Also my first exposure to Acton and Tocqueville.) More than any of the books listed so far, Hayek shaped how I think about the basic shape of the social world, and also how I think about the connections among normative, explanatory, and empirical social analysis. Though I'm not an economist, and one of the (minor but real) aims of my next book is to reject the intellectual history offered in Constitution, and to the best of my recollection the phrase "spontaneous order" doesn't appear in anything I've ever published, I still comfortably describe myself as a Hayekian in my intellectual outlook.
8) Gordon Wood, The Creation of the American Republic. I read this in Wood's own class on the American Revolution, from then on I not only had my model of what to try to live up to as a classroom teacher, I also had my real understanding of how research at the highest level and teaching at the highest level enriched, complemented, and completed one another, and why the profession of university professor hung together as a single vocation. (It's also, simply, a great book, but its influence on me was not only intellectual.)
9) Will Kymlicka, Liberalism, Community, and Culture. This book gave me my first actual research agenda-- and was written recently enough before I became a graduate student that I felt like I could be a contributor to a live intellectual debate. Incidentally, this was probably the first dissertation-book I read all the way through. (I couldn't make it through Liberalism and the Limits of Justice on my first attempt; at a certain point I said "I get it, already," and put the book down.) I tell doctoral students in political theory that they should have a couple of dissertation-books on their minds and on their shelves that they think are relevant to their work. This may sound cruel: a dissertation-book is not a dissertation, and students shouldn't be made to think that they need to write an Oxford University Press-quality manuscript in order to have a submittable dissertation. But I found it tremendously useful to have a model for size and scope. Good graduate students often want to propose dissertations that are vastly too big and too ambitious, and then get frustrated when they realize that doing what they want would take decades and thousands of pages. A dissertation-book that you admire can reassure you that something important and worthwhile can be accomplished in something about this big-- and that it's okay not to answer every possible question or master the whole of human knowledge. Kymlicka provided that book for me: a reminder of how much could be accomplished in a project of about that size, and also a reminder that a dissertation can be an impressive accomplishment without doing everything. Kymlicka convincingly opened up a space for more research (others' research as well as his own); he didn't wait until he'd done it all himself before scheduling his defense.
10-11) Tocqueville, The Ancien Regime and the Revolution; Isaiah Berlin, The Crooked Timber of Humanity. You'll have noticed a lot of American Revolution/ American founding material on this list, and I was as prone as anyone to a simple Whiggish sense of the connections among freedom, reason, and the 18th-century revolutions. Tocqueville and Berlin, in their different ways, helped to break me of that.