My two posts arguing that Christian belief is reasonable brought out precisely the sorts of incredulity I expected. In return, I thought I’d introduce you to some of the work in contemporary Christian philosophy that I have found convincing. I’m inviting you to reconsider the rational status of Christian belief. So let this post be a primer in contemporary Christian philosophy: an open door to start conversations about the possibility of rational Christian belief and religious belief generally. I worked hard compiling and linking to resources because I’m trying to honor your requests for more information and to respect your intelligence as rational individuals.
Over the last forty years, the field of Christian philosophy has exploded in richness and depth. Much of the work began following the founding of The Society of Christian Philosophers, in 1978. Today the SCP is the largest subgroup in the American Philosophical Association, with over 1100 members of Christians from a vast range of denominations and degrees of theological conservatism and liberalism. (I’m a member!)
These philosophers have produced hundreds of books working out answers to various questions raised by the Christian religion.
As I could tell from my last post, many of you feel that thoughtful arguments for Christian claims do not exist. I once felt similarly, and in this post I thought I’d explain why I changed my mind.
I divide my categorization of books into a wide range of categories on questions that directly or indirectly bear on the truths of the Christian religion.
I. Indirect Arguments for Core Christian Beliefs
I will begin with questions that bear indirectly, specifically books that convinced me to abandon the Christian worldview’s main intellectual competitor: naturalism. For me, these came in three categories, regarding the fail of naturalistic accounts of (i) mind (especially consciousness and intentionality), (ii) choice and free will and (iii) the nature of morality. Naturalism, which I understand as the view that all that exists is describable by science (empirical facts) or that are required to form scientific models (mathematics).
I don’t think that naturalism can account for or explain the nature of consciousness, specifically the phenomenon of qualia, or the unique features of conscious experience. I was most convinced by David Chalmers’ famous book, The Conscious Mind. John Searle’s works, especially The Rediscovery of the Mind, convinced me that we cannot give a naturalistic account of intentionality, the fact that mental states have propositional content (they’re about things). He also convinced me that the mind is not a computer, even if it has computational mechanisms.
But Chalmers convinced me Searle’s attempt to avoid dualism is a failure and Searle convinced me that Chalmers’ (then) epiphenomenalism was implausible. This led me to property dualism about mental properties, but I agreed with Searle that property dualism is unstable and collapses into substance dualism. And Richard Swinburne’s book, The Evolution of the Soul, and John Foster’s book, The Immaterial Self, convinced me that substance dualism was a perfectly respectable philosophical position. So I think there are souls, and I think I have darn good philosophical reason to think so.
Ib. Free Will
For years, I didn’t take issues of free will seriously, but Peter Van Inwagen’s famous book, An Essay on Free Will, convinced me that free will and moral responsibility were inextricably tied, and since I was unable to give up moral responsibility, I became a libertarian about free will. Namely, I occasionally have the power to do otherwise than I did. The initial conditions of the universe and the laws of nature do not preclude me from doing otherwise. I did other reading in the literature, but it was Van Inwagen that anchored me. I now take compatibilist challenges pretty seriously, especially those advanced by Michael McKenna, but I still think libertarians have the upper hand.
Many naturalists reject moral claims altogether. I always found that position not merely wrong but repulsive. There are things that are wrong to do and any worldview that cannot explain that some things are genuinely wrong is a bad worldview. Any conscientious person is sufficiently committed to condemning things like the Holocaust to abandon naturalism if she became convinced that naturalism could not explain the fact that the Holocaust was a terrible moral crime. And I came to believe that facts about goodness could not be grounded in desire or preference. Mark Murphy’s book, Natural Law and Practical Rationality, played a role here, but so did Nozick’s experience machine case in Anarchy, State and Utopia. There is an objective account of human interests and the human good that cannot be reduced to any natural facts. That is, there are normative facts, facts about what is good for us and what we should seek, that cannot be explained by scientific inquiry and that do not supervene on natural facts. Aristotle and Aquinas’s accounts of human nature and substantial forms helped me to explain why some things are good and bad for humans, and Aristotelian-Thomism is a serious, rich competitor to contemporary naturalisms. I also think Divine Command Theory has been rehabilitated as a serious moral theory by Robert Adams in Finite and Infinite Goods.
I became similarly convinced about the idea of right because, while I am a deontologist, I think that rightness is understood partly as a set of moral requirements to advance the good, and if the good cannot be naturalized, then I think it follows the right cannot be either. However, I am considerably more sympathetic to naturalistic accounts of rightness than goodness.
Id. What of Christianity?
Now, if you become a libertarian about free will, a substance dualist about mind and an objectivist about the human good, you most certainly do not have to be a Christian. But Christianity is committed to these views (in my opinion). And by showing that those commitments are correct, some of the biggest objections have been cleared away.
II. Direct Arguments for Core Christian Beliefs
Now I shall review works on the core Christian claims, specifically (a) arguments for God’s existence, (b) further arguments for the divine attributes, (c) arguments for rational belief in miracles, (d) arguments for rational belief in religious experience, (e) arguments for the reliability of religious texts like the Bible (not their infallibility), (f) arguments making sense of the doctrine of the atonement, (g) arguments that revealed doctrines like the Trinity, while sometimes mysterious, remain undefeated and (h) arguments that if theism is true, Jesus probably rose from the dead. There’s a lot more to say, but this, if I do say so myself, is a great start.
Note that there are Stanford Encyclopedia of Philosophy entries with bibliographies on most of these topics. You can also review another list of arguments here.
IIa. Arguments for God’s Existence
A great introduction is Richard Swinburne’s The Existence of God.
(i) Cosmological Arguments
Cosmological arguments attempt to demonstrate that God is the creator of the contingently existing cosmos. “Prime Mover” arguments are versions of cosmological arguments, but they’re not the best. The best cosmological arguments, in my mind, are arguments from the mere fact of contingent facts. If you adopt even a modest version of the principle of sufficient reason, the existence of a necessary being, or at least onenecessary concreta, basically follows as a matter of modal logic. Just check out the simple version in the SEP entry to evaluate this claim for yourself. The cosmological argument is plainly logically valid, and its core substantive premises are plausible and attractive in many ways. That’s as much from a philosophical argument as you might ask. I have a couple of favorite discussions of cosmological arguments. I think Ed Feser’s discussion of Aquinas’s five ways in his Aquinas is especially accessible, though I quite like the considerably harder analysis of Aquinas’s arguments in Norman Kretzman’s commentary on Aquinas’s Summa Contra Gentiles in The Metaphysics of Theism: Aquinas’s Natural Theology in Summa Contra Gentiles I. I think Leibniz’s argument is still pretty damn good, but I like the two recent, anthologized versions advanced by Richard Taylor here. I quite like (though haven’t finished) Alex Pruss’s book on the principle of sufficient reason, The Principle of Sufficient Reason: A Reassessment and my friend Josh Rasmussen’s cutting edge work in the area. Here’s his piece, “From States of Affairs to a Necessary Being” in Phil Studies and his piece, “A New Argument for a Necessary Being” in the Australasian Journal of Philosophy.
You can check out Alex Pruss’s page on cosmological and ontological arguments here.
Here’s a short paper of Pruss’s defending his very restricted version of the PSR.
Oh, and if you’re interested, Josh has set up a neat page trying to test intuitions to see if they entail the existence of a necessary being here: www.necessarybeing.net
Also see Doherty’s awesome bibliography here.
(ii) Ontological Arguments
Cosmological arguments, at least in their first stage, only get you at least one necessary being. I think it will follow on analysis of the very idea of a necessary being that certain divine attributes follow. However, that takes more work. The promise of ontological arguments is to get you to something very much like God pretty darn quickly. The problem with ontological arguments is that they initially seem to reek of bullshit. The awesome thing about ontological arguments is that it’s actually really hard to explain what is wrong with them. You might consider reviewing David Lewis’s amazing attempt to identify the real problem here in Chapter 2, “Anselm and Actuality” in the first volume of his Philosophical Papers. I think Anselm’s argument works iff you accept his neo-Platonic metaphysics, which I think is weird but not insane. There’s a much more worked out version in his Monologion, which predates the much more famous Proslogion. I think the SEP entry shows why Kant didn’t definitively refute ontological arguments, as I think most philosophers personally believe. The fact is plenty of ontological arguments just don’t depend on treating existence as a predicate. I think Plantinga develops a pretty novel modal version of the argument in Chapter 10 his wonderful book, The Nature of Necessity. The problem with the modal ontological argument is that while it follows as a matter of (somewhat contentious) modal logic that if God is metaphysically possible, then He necessarily exists, it also follows that if God is metaphysically possibly-not, then He is impossible. But if you can be rationally justified in believing that there exists at least one possible world in which a Maximally Great being exists, then simple modal axioms entail that God exists in this possible world, the actual world. And Plantinga says in his famous article that he’s merely trying to show that there is an ontological argument that can justify theistic belief.
(For libertarians: Pruss is awesome. He’s like a Catholic Robin Hanson: inventive mind, ridiculous math and formal chops, willing to consider completely bizarre and fun scenarios as a guide to truth. And he blogs.)
Also see Doherty’s awesome bibliography here.
(iii) Teleological Arguments
Teleological arguments generally try to establish that God exists based on the presence of intelligently designed features of the universe. You are probably most familiar with the biological versions of the argument most famously advanced by William Paley. Paley was actually really freaking smart and I encourage you to read his famous book, Natural Theology. He anticipates a Darwin-like challenge that design could arise as a series of very minor alterations, but argues that the design inference is nonetheless valid. I think design inferences are licensed so long as the presence of order in the world is more probable on the conjunction of theism and evolution than on the conjunction of atheism and evolution. And I think it’s perfectly plausible to think as much.
But the better teleological arguments in my mind are the cosmological fine-tuning arguments, especially the cool one advanced by Rob Collins, which you can find here. Here also has a great website on the fine-tuning argument here. Collins has advanced the view that on the assumption that the cosmological constants of physics could have had different values, a quite strong case for the existence of a powerful, good, intelligent being can be made. I agree with him.
Also see Doherty’s awesome bibliography here.
(iv) Properly Basic Belief
Now, I don’t think you actually need any of the classical theistic arguments to demonstrate that theism can be epistemically justified. Reformed epistemologists have been arguing as much for decades. The idea, roughly, is that belief in God can be properly basic, or held without any justifying reasons at all. Now, Reformed epistemologists take on a kind of theistic reliabilism about whether one is entitled to or warranted in believing a great many things. This means that so long as one’s cognitive faculties reliably track the truth, rational belief does not require any internal psychological access to one’s justifiers for one’s beliefs. I don’t find reliabilism all that plausible outside of perceptual beliefs, but I think it’s a perfectly respectable way to go. I think what Plantinga showed in his wonderful God and Other Minds is something simpler, namely that belief in God has the same epistemic status as belief in other minds. There’s no way to prove to all rational persons that God exists, nor is it possible to prove that other minds exist. For all I know, you’re a bunch of zombie meat husks with no consciousness. But my belief is nonetheless justified. Of course, Plantinga has the great, magesterial work on the matter, Warranted Christian Belief, where he works out his most detailed statement of Reformed epistemic approaches to Christian belief, but there are perfectly respectable internalist ways to go as well.
The general point here is that I think atheists implicitly hold the rationality of theistic belief to absurdly high standards, far beyond the rationality of belief in all sorts of weird views. I don’t think that asymmetric treatment can be justified, not even a bit.
You’ll want to see Platinga and Wolterstorff’s book on Faith and Rationality.
IIb. Arguments for the Divine Attributes
Now many of you are no doubt thinking that even if the theistic arguments are sufficient to justify belief, they don’t prove that the God of Christianity exists. This is true, though the ontological argument comes rather close, though admittedly it is the most dicey. However, combinations of these arguments can get us quite a bit. For instance, a cosmological argument can give us omnipotence (since God ultimately explains all contingent facts) and that God is personal (since a necessary being cannot be material, since matter can cease to exist). Further, since God knows how to create the universe, he must know quite a bit. The teleological argument can strengthen our convictions in God’s power and intelligence. We can also see God’s benevolence in creation in various ways, though obviously the problem of evil is a very powerful challenge here. However, there are lots of arguments that follow the establishment of the more modest premises in the traditional theistic arguments, what we often call “stage 2” of theistic arguments. There are so many divine attributes, so I can’t say too much here that’s at all definitive. But I will point you to the discussion in Kretzmann (here and here) and Stump (here, especially Part I), which are the ones I’ve paid most attention to besides reading Aquinas himself.
If you’re interested, here are some other recommendations. Check out my friend Josh Rasmussen’s piece, “From a Necessary Being to God,” here (ungated).
Also see Doherty’s awesome bibliography on the divine attributes here.
(i) Divine Eternality, Simplicity
But let me sketch some of the arguments in their generic form. If there exists a necessary being, it obviously exists at all points in time, so the being is eternal. And arguably a necessary being cannot have parts, since if it had parts, those parts could conceivably come apart. If so, then God must be perfectly simple.
(ii) Divine Omnipotence and Intelligence
If God is the source of all contingency, then it seems He can do a great many metaphysically possible things, which doesn’t show perfect omnipotence, but is pretty damn close. And of course omnipotence does not involve doing the logically impossible, since there’s nothing that there is to be logically impossible.
What’s more, God is an intelligence because he is a causally endowed immaterial being. A necessary being cannot be a material being because matter can cease to exist. And if he isn’t matter, he must be either mental or abstracta. And since abstracta lack efficient causal power, he must be mental. So God is an intelligence, a pure spirit.
And since God is a causally endowed intelligence, then all his causal power is based on his reasoning and will. If so, it’s hard to see how God couldn’t be spectacularly intelligent. If that doesn’t do it for you, then source the cosmological fine-tuning argument, which shows that God’s handiwork is pretty darn spectacular. He must be pretty smart.
(iii) Divine Goodness
A necessary being must be a good being, on Aquinas’s view, because a being that is the source of all contingency must possess all the “perfections,” which is a kind of Platonic argument I don’t entirely understand. My reason for thinking that God is all good is that a simple being cannot possibly be evil because evil requires a rational misapprehension of the good and at least some degree of self-deception. A simple mind has no parts to it, and so cannot hide anything form itself. It is incapable of the cognitively necessary conditions for doing evil. So that’s why God is good. He’s good for other reasons, but there’s one I find interesting.
The divine attributes are relatively unexplored territory in contemporary Christian philosophy. People work on it, but I think there are a lot of cool questions that haven’t been given as adequate a treatment. But in all likelihood, my turn to moral and political philosophy, along with political economy, has led me to overlook a lot of good literature. So here are some recommendations:
(a) Omnipotence: Flint, T., and A. Freddoso. “Maximal Power.” In The Existence and Nature of God.
(b) Omniscience: Kvanvig, Jonathan. The Possibility of an All-Knowing God.
(c) Eternity: Helm, Paul. Eternal God.
(d) Simplicity: Brower, Jeffrey. “Making Sense of Divine Simplicity.”
IIc. On Miracles
A lot of people think that Hume’s criticism of belief in miracles is decisive. I don’t. There is a lot of writing on this, but I like C.S. Lewis’s brief discussion in his book Miracles and Swinburne’s discussions in various books, all the way from his short work, The Concept of a Miracle in 1970 to his discussion in The Resurrection of God Incarnate. The basic idea of Lewis’s critique and a number of others is that the probability of miracles is heavily dependent on the probability of theism, so the probability of miracles is relative (surprise) to your background beliefs. It’s rather hard, accordingly, to show that belief in miracles (like the resurrection of Jesus Christ) is irrational in general.
See this piece: McGrew, Timothy & Lydia, 2009, “The Argument from Miracles,” in William Lane Craig and J. P. Moreland, eds., The Blackwell Companion to Natural Theology.
Here’s the SEP on miracles. It’s written by Tim McGrew, who I’m told is excellent on the topic, but I haven’t read him.
IId. On Religious Experience
The classic work on the veracity of religious experience is William Alston’s Perceiving God, which had a major impact on me. Alston thinks that if God exists, we can be warranted in believing we have experienced Him when He contacts us. The work is based on a form of Reformed epistemology, but I think its arguments can be broadened beyond that perhaps more controversial basis. Alston has an interesting argument that we aren’t capable of validating experiential practices outside of the practice itself for just about any sensory practice, so the same might be true for our faculty for perceiving God.
IIe. On Religious Texts
Two great books arguing in favor of the rationality of belief in divine revelation, say through religious texts are Swinburne’s classic Revelation: From Metaphor to Analogy and Sam Fleischacker’s recent book, Divine Teaching and the Way of the World: A Defense of Revealed Religion, which I just reviewed for Mind.
IIf. On the Atonement
Again I love Swinburne here. I like his Responsibility and Atonement, but I also like Eleanore Stump’s discussion of atonement in her book, Aquinas in Chapter 15. And, well, I like Anselm! See Cur Deus Homo, which outlines the substituionary view. It includes some wild assumptions that aren’t necessary to the defense, however, as Swinburne and Stump show, I think.
IIg. On the Trinity
The Trinity is the doctrine I’ve read about least. I think the idea is mysterious, but I know enough people who read and write about it that I think I have good reason to think I can avoid proposed defeaters for my views. A lot of you think, “Well, it’s dumb because three can’t be one. QED.” But obviously the doctrine is the God is three in one sense and one in another. So unless you know those distinct senses, I’m not sure you have a defeater in hand. You can find recent literature below (like Swinburne’s non-orthodox view), but I still think Augustine’s On the Trinity is pretty good, as it Aquinas’s discussion in the Summa (discussed here). The real question here is (a) whether the doctrine is coherent and (b) whether it is Scripturally grounded. I have only read about (a). My ground for (b) is my belief that God established a Church to think through these issues, so I rely on the ecumenical councils for my information. I consider them experts and can defend that view if you like.
SEP entry here. (Yes, they even have an entry on The Trinity; the SEP is awesome).
IIh. On the Resurrection
This one is pretty critical because it’s one of the core claims that many contemporary Christian philosophers used to draw people into the faith. I still love Swinburne’s The Resurrection of God Incarnate and find Lewis’s discussion in Mere Christianity a good introduction, though not a good place to end one’s inquiry. But there are so many books on the matter, ranging from The Case for Christ all the way up the ladder of philosophical sophistication to Swinburne, with everything in between. And of course you cannot discuss this topic without referring to all of William Lane Craig’s books on the subject. There are several debate books, but one stand alone is The Son Rises: The Historical Evidence for the Resurrection of Jesus. Please note that these aren’t proofs that atheists should believe that Jesus rose. Instead, I think they’re sufficient to justify theists in believing that Jesus rose from the dead.
III. Replies to Core Objections to Christian Beliefs
The books cited have already answered many objections to Christianity, such as that God does not exist, that the Gospels are unreliable, that the atonement and the Trinity make no sense. But three big problems remain (in increasing order of importance: (a) the problem of hell, (b) the conflict between science and religion, (c) the problem of divine wickedness and (d) the problem of evil. I won’t cover the problems of divine hiddenness and petitionary prayer.
IIIa. The Problem of Hell
Lots of Christian philosophers are universalists these days. Maybe most are, so there’s no problem of hell because everyone gets out eventually. For a core Christian challenge to the doctrine of hell, see Marilyn McCord Adams’s article, “The problem of hell: a problem of evil for Christians” in Reasoned Faith: Essays in Philosophical Theology in Honor of Norman Kretzmann (. Follow the citation path from there. I think the doctrine makes sense so long as everyone there prefers God’s absence to God’s presence, such that Lewis was right in saying the gates of hell are locked from the inside. I quite like his discussion in The Great Divorce.
Also see Jon Kvanvig’s book (which I’m told is great): The Problem of Hell.
IIIb. Science and Religion
There is so much on the science-religion conflict I can’t begin to review it adequately. You can read Alvin Plantinga’s SEP entry on the matter. I love, love, love his new book on the matter, Where the Conflict Really Lies: Science, Religion and Naturalism, which just came out. I think Plantinga decisively shows that there is no conflict between physics and evolutionary biology on the one hand and the core Christian creeds on the other. Basically, on theism, science describes the regularities that obtain when God does not engage in special action, but God can engage in special action from time to time, rarely, so as not to render scientific claims anything but extremely probable. But God doesn’t need to upset the order of nature very much for core Christian claims to be true. What’s more, naturalism and evolution are in tension with one another.
Again, here’s the SEP entry.
IIIc. Divine Wickedness
Again, there’s a lot here, but for a series of struggles to make sense of divine action in the Old Testament see this reader: Divine Evil: The Moral Character of the God of Abraham for some defenses and attacks drawn from a recent conference on the matter. I’m a Stump guy myself, but Wolterstorff and Swinburne’s contributions are interesting, alone with Mark Murphy’s. You can check out an NDPR review here.
IIId. The Problem of Evil
Finallywe reach the granddaddy of all problems for Christianity and theistic belief general, the problem of evil. Importantly, the problem of evil literature has exploded since Mackie’s challenge in The Miracle of Theism. Plantinga is widely believed to have refuted Mackie’s version of the problem, which purports to show that there is no possible world in which God and evil coexist. Plantinga shows that there is at least one possible world in which humans have libertarian freedom and God cannot actualize the world without permitting them to commit evil due to the fact that some of these people possess transworld depravity. He argues as much in The Nature of Necessity, but the solution is famous enough in the field to have a Wikipedia entry. Since then people have focused on analyzing the evidential problem of evil, which holds that evil is counterevidence to God’s existence. For anthologies of problems and solutions for both the logical and evidential problems see The Problem of Evil (Oxford Readings in Philosophy), edited by Marilyn McCord Adams and Robert Merrihew Adams. Also see Daniel Howard-Snyder’s reader, The Evidential Argument from Evil, which has Stephen Wykstra’s famous skeptical reply. These days skeptical theism is a big philosophical project, with Michael Rea having over a million dollars to study the view. I buy into a strong form of skeptical theism where I believe I am justified in (a) affirming theism, (b) affirming that God has morally sufficient reason to permit evil and (c) affirming that neither I nor any other human is in an epistemic position to know what those particular reasons are.
I like Van Inwagen’s discussion in his recent book, The Problem of Evil.
I’m told (but haven’t confirmed) that William Hasker’s book on evil is excellent. See his book, The Triumph of God over Evil: Theodicy for a World of Suffering.
But let me say this:
Few books in philosophy have changed my life. But reading early versions of Eleanore Stump’s book Wandering in Darkness made the philosophical and personal questions I had about evil concrete in a powerful way that continues to move me. The book is nothing short of extraordinary, a true tour-de-force. It is beautiful.
For a brief overview of recent work in the area, see Trent Dougherty’s piece in Analysis.
Also see Doherty’s awesome bibliography on the problem of evil here.
So I’ve given you a brief overview of recent philosophical work I have found extremely useful in (a) rebutting Christianity’s main philosophical competitor, naturalism, (b) establishing epistemic justification for core Christian claims and (c) successfully rebutting powerful objections.
Now, suppose someone like me reads many of these books and decides that Christianity is true. Is she stupid or ill-informed? Did she fail to discharge her epistemic duties? Is she simply guilty of motivated cognition and wish fulfillment? Or has she acquitted herself with a highly respectable degree of reasoning?
I understand that many of you want to resist what I’m saying. But given this background, are you still as sure as you were that a rational person under modern conditions can’t be a Christian? All I’m asking is for you to entertain the idea that rational Christian belief is possible.
- A Bleeding Heart History of Libertarian Thought
- Academic Philosophy
- Blog Administration
- Book/Article Reviews
- Current Events
- Rights Theory
- Rothbard's Ethics of Liberty
- Social Justice
- Symposium on Free Market Fairness
- Symposium on Huemer's Problem of Political Authority
- Symposium on Left-Libertarianism
- Symposium on Libertarianism and Land
- February 2015
- January 2015
- December 2014
- November 2014
- October 2014
- September 2014
- August 2014
- July 2014
- June 2014
- May 2014
- April 2014
- March 2014
- February 2014
- January 2014
- December 2013
- November 2013
- October 2013
- September 2013
- August 2013
- July 2013
- June 2013
- May 2013
- April 2013
- March 2013
- February 2013
- January 2013
- December 2012
- November 2012
- October 2012
- September 2012
- August 2012
- July 2012
- June 2012
- May 2012
- April 2012
- March 2012
- February 2012
- January 2012
- December 2011
- November 2011
- October 2011
- September 2011
- August 2011
- July 2011
- June 2011
- May 2011
- April 2011
- March 2011
- Liberty Law Blog
- Students for Liberty
- Skeptical Libertarian
- PEA Soup
- Public Reason
- George H. Smith - Excursions
- Rad Geek People's Daily
- Cato Unbound
- Austro-Athenian Empire
- Cato @ Liberty
- Knowledge Problem
- Economic Thought
- New APPS
- Crooked Timber
- Center for a Stateless Society
- Coordination Problem
- Economics and Ethics
- Liberty Law Blog
Follow me on TwitterMy Tweets
Tagsacademic philosophy anarchism basic income bleeding heart libertarianism Bryan Caplan charity coercion crooked timber economic liberty education exploitation feminism foreign policy free market fairness Friedrich Hayek history ideal theory immigration inequality John Rawls John Tomasi left-libertarianism liberalism libertarianism liberty Murray Rothbard non-aggression principle non-ideal theory Piketty political science poverty property-owning democracy property rights racism religion Robert Nozick Ron Paul self-ownership social justice Students for Liberty sweatshops Thick Libertarianism universal basic income war work