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Practical Reason and Theoretical

Investigations Of The Types Of Reason

In the early twenty-first century, there are three sets of problems concerning practical reason: one that mostly relies on Aristotelian resources, a second that bases its inquiries on Kantian problems and texts, and a final group that derives from Machiavelli and Hobbes. The Aristotelian branch of the problem seeks to revive notions of phronesis, prudence, or practical wisdom by showing how practical rationality is not reducible to theory or to instrumental reasoning. Aristotelian practical reason is concerned with the virtues of practical reason, and their relation to the virtues of character. It looks to knowledge of particulars, rationality that does not exclude emotion. It tries to interpret Aristotle's enigmatic sentence: "Thought by itself moves nothing, but only thought directed to an end, and dealing with action" (Ethics, VI.2.1139b1). Practical reason here is substantive, and therefore the challenge is in seeing whether it is not confined to codifying what the supposedly virtuous person already embodies, and therefore whether it is not parochial. Much of the Aristotelian revival tries to use Aristotle to confront problems beyond the scope of his original concerns. It seeks to overturn the modern distinction between moral and prudential reasoning. It asks whether, and how, practical reason can maintain its autonomy in the face of the increased domination of scientific reasoning in our lives, and without the strong practical conditions Aristotle imputed to the polis, such as confidence that ordinary political judgments were reliable enough that moral reasoning can defer to the ultimate authority of the person of practical wisdom. (Seminal here is Alasdair MacIntyre's 1984 After Virtue: A Study in Moral Theory. See also Eugene Garver's Aristotle's Rhetoric: An Art of Character [1994] and For the Sake of Argument: Practical Reasoning, Character, and the Ethics of Belief [2004].)

The different ways Kant poses the question of critical philosophy for theory and practice reflects the success of science. The scientific revolutions of the seventeenth century apparently made progress by changing the idea of theoretical reason from a substantive one, in which scientific reasoning succeeded by tracking or imitating the rational structure of the universe, to a procedural one, in which something new, called the "scientific method," succeeded just because its neutrality and purity allowed it fairly to interrogate nature. After such progress, practical reason, too, was tempted to become procedural. Therefore, the Kantian side of the current investigation of practical reason instead asks how reasoning can transfer motivation from an initial desire along the chains of reasoning to a conclusion about what to do.

The Kantian investigation of practical reason asks not about virtues but capacities and possibilities. "A practically rational person is not merely capable of performing certain rational mental operations, but capable also of transmitting motive force, so to speak, along the paths laid out by those operations" (Korsgaard, p. 320). Corresponding to skepticism about theoretical reason, the Kantian inquiry asks whether all the motivating force of reasoning must come from an irrational source, or whether practical reasoning can itself be motivating. Practical reason here is procedural, and so from the beginning the challenge to Kantian practical reason is whether it can give specific guidance. The analogy to logic is clear. If logic is pure procedure, it can detect fallacies and justify inferences, but it cannot generate truths of its own. Can practical reason tell one anything one does not already know by desire or other sources of ends?

Even before the scientific revolutions of the seventeenth century, philosophers had to change the terms in which they thought about practical reason because of the earlier revolution, instituted most dramatically by Machiavelli and Hobbes, of separating ethics from politics and therefore the practical reasoning of the individual moral agent and of the state or the politician. Unfortunately, the separation of ethics from politics has resulted in these three research programs concerning practical reason having little communication among them. The Kantian, and most of the Aristotelian, explorations of practical reason concentrate only on the practical reasoning of the individual moral agent. There is a rich but distinct literature concerned with how individuals can, or cannot, coordinate their choices and actions through such research programs as game theory. Finally, problems of "dirty hands" and the relation between political morality and "real" or individual morality form a research program of their own.

In Isaiah Berlin's influential formulation, Machiavelli inaugurates a new era in practical reason by denying the existence of a single highest good, claiming instead that not all good things can coexist. Regardless of whether Berlin's account accurately describes Machiavelli, it rings true as a description of the contemporary predicament of practical reason. Toleration and compromise head the agenda for practical reason. Stoics once wondered whether someone could be happy on the rack; the readers of modern philosophy ask instead whether happiness is possible in the face of abundance.


Berlin, Isaiah. "The Originality of Machiavelli." In Studies on Machiavelli, edited by Myron P. Gilmore. Florence: Sansoni, 1972.

Dahl, Norman. Practical Reason, Aristotle, and Weakness of the Will. Minneapolis: University of Minnesota Press, 1984.

Davidson, Donald. "How Is Weakness of the Will Possible?" In his Essays on Actions and Events, 21–42. Oxford: Clarendon, 1980.

Garver, Eugene. Aristotle's Rhetoric: An Art of Character. Chicago: University of Chicago Press, 1994.

——. For the Sake of Argument: Practical Reasoning, Character, and the Ethics of Belief. Chicago: University of Chicago Press, 2004.

Hume, David. A Treatise of Human Nature. Edited by L. A. Selby-Bigge. Oxford: Clarendon, 1978.

Korsgaard, Christine. The Sources of Normativity, Cambridge, U.K.: Cambridge University Press, 1996.

MacIntyre, Alasdair. After Virtue: A Study in Moral Theory. 2nd ed. Notre Dame, Ind.: University of Notre Dame Press, 1984.

Mill, John Stuart. Utilitarianism. London: Parker, Son, and Bourn, 1863. Text available at http://www.utilitarianism.com/mill1.htm.

O'Neill, Onora. Constructions of Reason: Explorations of Kant's Practical Philosophy. Cambridge, U.K.: Cambridge University Press, 1989.

Searle, John. Intentionality: An Essay in the Philosophy of Mind. Cambridge, U.K.: Cambridge University Press, 1983.

Weber, Max. "The Profession and Vocation of Politics." Originally published as "Politik als Beruf." Available in translation in Weber: Political Writings, edited by P. Lassman and R. Speirs. Cambridge, U.K.: Cambridge University Press, 1994.

Eugene Garver

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Science EncyclopediaScience & Philosophy: Quantum electronics to ReasoningPractical Reason and Theoretical - Definitions And Relationships, Investigations Of The Types Of Reason, Bibliography