Critique of Practical Reason Summary

Summary (Critical Survey of Literature for Students)

In The Critique of Practical Reason, Immanuel Kant argues that principles are subjective (and therefore maxims) if one person considers them; they are objective (and therefore imperatives) if every rational being considers them. Imperatives are either hypothetical or categorical. A hypothetical imperative demands a course of action to achieve a specified result; for example, “If I want to stay dry in the rain, then I should take my umbrella with me.” A categorical imperative demands a course of action under all possible circumstances; for example, “Thou shalt not commit murder.”

According to Kant, hypothetical imperatives respond to desires, while categorical imperatives constitute rationality. Subjective principles and hypothetical imperatives are empirically oriented; neither can be a fundamental determiner of moral motivation since they serve self-interest. Proper moral motivation cannot follow fleeting pleasures or displeasures; it must follow a noncompromising rationality. Rational beings must imagine their maxims as practical and general laws that fit into a mold of moral rationality. No matter what one plans, the logical form of rationality urges a logical analysis of one’s actions. To test one’s decisions, one uses an imperative, which is immutable. A basic requirement of morality, autonomous motivation, undergirds this immutable law. Any heteronomy entails random authority (Willkür).

Objects inspire pleasure or displeasure; rationality must be free of empirical attractions, having nonsubjective status. Kant provides an example of testing by rationality: Kant is the recipient of a deposit. The owner has died without leaving a financial record for his heirs. However, Kant cannot deny the existence of the deposit even though no evidence of the deposit exists. If everyone who entered into a contract did so planning to deny the existence of that contract, contracts themselves would cease to exist, rendering the act of falsely contracting itself incoherent.

Kant’s example depends upon his formulation of the categorical imperative: “Act such that the maxim of your will can always count also as a principle of general legislation for all.” In other words, it should always be logically possible for the maxim behind one’s action (for example, “I should only keep promises when it is convenient”) to be universalized (for example, “Everyone who finds their promises inconvenient should break them”). The reason this example maxim cannot be generalized is that, if it were, there would no longer be such a thing as a promise. Thus, generalizing the maxim results in logical incoherence, violating the laws of reason.

Kant’s practical rule is unconditional; thus, it is a categorical, practical proposition with an a priori truth-value. Even when one follows subjective desires, one must be able to imagine them as tested by moral law. This law is not a derived one; it urges itself upon the mind as part of the structure of rationality as such. Any search for happiness must include the search for the happiness of all who share in one’s rationality. The moral community that this concept refers to may vary with changing times and views; Kant does not commit to one ethnic group or even one species.

Selfish expansion of one’s happiness makes no sense as a moral ideal. Kant gives the example of an Epicurean reference: If one were to recommend a particular job candidate to maximize the candidate’s own pleasures, wealth, or power, a human-resource specialist would reject the recommendation as either mad, mocking, or backstabbing. Furthermore, if one acts wrongly, one must be able to conceive of a punishment for wrongdoing. However, it would be nonsensical to anticipate punishment—that is, a reduction of well-being—in return for reducing one’s well-being by not sufficiently seeking happiness. Thus, seeking happiness cannot be a moral virtue. Morality is rooted in rationality, not in Epicurean pleasure.

In the Kritik der reinen Vernunft (1781; Critique of Pure Reason, 1838), Kant had shown that time and space are mental conditions of how the mind perceives the world. Beyond these phenomena, one can know of a thing-in-itself but cannot experience it. A similar relationship obtains between humans as natural beings and humans as...

(The entire section is 1776 words.)

Critique of Practical Reason Bibliography (Critical Survey of Literature for Students)

Further Reading

Beck, Lewis W. A Commentary on Kant’s “Critique of Practical Reason.” Chicago: University of Chicago Press, 1960. A useful explication of Kant’s moral philosophy.

Freydberg, Bernard. Imagination in Kant’s “Critique of Practical Reason.” Bloomington: Indiana University Press, 2005. Detailed study of the role of the imagination in Kant’s philosophy of mind and of its function within his moral system.

Kant, Immanuel. Translated by Werner S. Pluhar and Stephen Engstrom. Critique of Practical Reason. Indianapolis, Ind.: Hackett, 2002. This volume contains a review of translations and their difficulties by Pluhar.

Wilson, E. “Kantian Autonomy and the Moral Self. ” Review of Metaphysics 62, no. 2 (2008): 355-381. Takes Kant to task about some of the concepts that he leaves open. Kant assumed free will, God, and an eternal soul as needed for moral thinking; Wilson presses for answers and clear commitments.