As I understand the Republic , the overarching aim of the work is to explain the nature of justice, specifically justice as a quality of individual human beings: in order to elucidate the nature of justice in the individual, Socrates introduces an analogy between justice in the state and justice in the soul. While I believe that Plato not only thinks that there is indeed a close enough similarity between the state and the individual human soul for the analogy between them to be genuinely illuminating, and, moreover, that there must be some relationship between justice in the state and justice in the individual soul if the use of the word 'justice' in both cases is not to be equivocal, I think that the question of whether there is indeed a relevant enough similarity between the state and the soul for the analogy to be fruitful, and, hence, the question of whether it might not be correct to think that justice in an individual is different from justice in the state--neither of which is engaged at any...

I myself find Zizek to be very interesting, although I am not familiar enough with his work as a whole to assess it. One problem I find Zizek's work to pose is that he is operating outside the standard categories used by most analytic philosophers, especially because his work is so thoroughly soaked in a particular understanding of Freud deriving in large part from Lacan's rereading of Freud. However, in an article in the July 12, 2012 issue of The New York Review of Books , "The Violent Visions of Slavoj Zizek," John Gray argues Zizek's work, "achieving a deceptive substance by endless reiterating an essentially empty vision...amounts in the end to less than nothing." I recommend this article to you, but I also recommend that you keep reading Zizek's work in order to assess Gray's criticisms for yourself.

You're absolutely right on in how you're thinking about the difference between Kant's approach to moral philosophy and that of his predecessors. Kant's predecessors took morality to be based on something external (such as, for example, God, or the achievement of some end), what Kant called 'heteronomous' conceptions of morality; Kant thought that morality consisted in autonomy , the capacity of rational agents to determine the rightness or wrongness of actions by a law that they gave themselves. (On the relation between Kant's ethics and that of his predecessors, I highly recommend J. B. Schneewind's magisterial The Invention of Autonomy: A History of Modern Moral Philosophy .) This law that agents gave themselves, Kant suggested in the Groundwork of the Metaphysics of Morals could be tested in particular cases by trying to determine whether one's intention--or, to use Kant's technical term, one's 'maxim'--could be universalized. (Note that there are various formulations of this...

You raise--in Sartrean terms--the excellent question of whether Sartre engages what contemporary philosophers call 'the problem of free will', the problem, that is, of how, if determinism, according to which every event is caused by some preceding event, is true, agents can be said to make free choices or determine themselves. Recent philosophical answers to this problem fall broadly into three classes: compatibilists believe that even if every event, including human choices, are determined by some preceding event, human beings are nevertheless free; incompatibilists believe that if every event is determined by some preceding event, then only if human choices are not determined by some preceding event can they be free: libertarian incompatibilists believe that human choices are not determined by preceding events, and therefore agents are free, while other incompatibilists believe that because human choices, like all other events, are caused by preceding events, human beings are not free. In light of...

There are many reasons why Descartes is taken as a reference point for early modern metaphysics and epistemology rather than Leibniz: I present a few. Descartes preceded Leibniz, and certain of Leibniz's philosophical innovations, and especially those in the philosophy of mind, were developed in response to Descartes, who continues to be referred to as 'the father of modern philosophy'. Many of Leibniz's most interesting philosophical works were not published during his lifetime--or even for many years after his death--and he wrote no single, magisterial statement of his views in metaphysics and epistemology like Descartes's Meditations , so it is somewhat more difficult to isolate Leibniz's views than it is to do so for Descartes. Although all professional philosophers are exposed to Descartes's Meditations --most likely, multiple times--over the course of their training, and may even teach the work itself, or at least parts of it, even if they are not specialists in the history of early modern...

Although it does indeed seem to be the case that agents seem knowingly to do evil--one thinks of Milton's Satan, who says, "evil be now my good"--and that Socratic intellectualism, most clearly expressed, if I remember correctly, in the Protagoras --cannot be correct. But it seems to me that Socratic intellectualism--as it is sometimes called--presupposes a very strong conception of knowledge, one which most agents, including, probably, Milton's Satan, fail to achieve. The basic idea seems to me to be that if one had full or complete knowledge, then one couldn't do evil willingly. (In part because one would thereby know that in doing evil, one was failing to act in accordance with some virtue or another. So Socratic intellectualism seems to be closely connected to the Socratic view that all virtues are connected--the 'unity of the virtues'--and that all virtues are identical to knowledge. Given those assumptions, the Socratic view seems to be plausible; independent of the views attributed to...

One often finds philosophers appealing to the intuitions of the 'folk', or, as an earlier strand of Anglo-American philosophy put it, the views of 'the man on the Clapham omnibus'. Such appeals play a variety of roles in philosophizing--they can be used as the basis for a position that is more clearly to be articulated, or a position against which to argue--but it's not always altogether clear to me what basis there is for such appeals. Why, I am tempted to wonder, should the 'intuitions' of the folk about philosophical issues be any more relevant to philosophers than folk intuitions about the nature of the physical world should be of interest to physics? Such methodological issues were prominent in the heyday of ordinary language philosophy, when great philosophical emphasis was placed on what is said when as a guide to clarifying philosophical issues. (The greatest practitioner of ordinary language philosophy, or what this practitioner himself called 'linguistic phenomenology', was, to my mind, J. L...

Although one way to work one's way into philosophy is to begin with philosophical problems, such as those considered in the books mentioned by Allen, another way--which I myself find more congenial, which, for what it's worth, is the way I myself came into philosophy--is to study its history. (Philosophy, Stanley Cavell has written, can be seen as a set of problems , but it can also be seen as a set of texts .) Plato's Republic is a text that sets out a host of problems taken up in subsequent texts. (Hence it was said that Western philosophy is a series of footnotes to Plato.) So I think that working through the Republic is a respectable, albeit most ambitious, way to work one's way into philosophy. The problem that you raise about Book 1 is very interesting: Socrates himself was accused--at least, according to Plato, by his enemies--of being a dialectician, a rhetorician--and Book 1 of the Republic seems to support this charge. In this respect, it's akin to certain of Plato's ...

Russell's History of Western Philosophy , while consistently entertaining, and worth reading on that score, is not a reliable source for knowledge about the philosophers it treats. The work may be not altogether unfairly described as one of the several 'shilling shockers' that Russell, who always needed money, wrote: sales of the History of Western Philosophy guaranteed Russell's financial security for the rest of his life. I myself don't know of a good single-volume history of Western philosophy. Anthony Kenny has written multiple volumes on the history of Western philosophy; there is also a very fine series, published by Oxford University Press, with volumes covering various periods in the history of Western philosophy, including Terence Irwin on Classical Thought, John Cottingham on the Rationalists, and Roger Woolhouse on the Empiricists, but I can't vouch for the quality of the other volumes. Perhaps other respondents know of a good single-volume treatment of the history of Western...

You're quite right about Kant. The purposiveness--orderliness--of organisms in particular and, indeed, of nature in general, while manifest in experience, cannot themselves, according to Kant, be proven from experience. In the Critique of Judgment (henceforth referred to as 'KU' and cited from James Creed Meredith's translation, revised by Nicholas Walker [Oxford University Press, 2007]), Kant explains that the principle of the intrinsic purposiveness of organisms "must be derived from experience....But owing to the universality and necessity which that principle predicates of such purposiveness, it cannot rest on merely empirical grounds, but must have some underlying a priori principle" (§ 66). Since, however, according to Kant, and in accordance with Kant's understanding of Newtonianism, nature itself is merely a realm of efficient causes, there is no room in nature for purposiveness (KU § 66), which leads to an antinomy of teleological judgment (KU §§. 69-78, esp. §§. 69-71), very roughly...