The Critique of Practical Reason

The Critique of Practical Reason is a foundational work in moral philosophy by Immanuel Kant, published in 1788. In this work, Kant argues that morality is based on reason, and that we have a moral duty to act in accordance with the categorical imperative.

The Categorical Imperative

The categorical imperative is Kant's principle of morality. It states that we should act in such a way that our maxim, or our subjective principle of action, could be made into a universal law. This means that we should act only on maxims that we can consistently will that everyone should follow.

For example, the maxim "I should steal this money because I need it" cannot be made into a universal law. If everyone stole whenever they needed money, then there would be no money left for anyone to steal. Therefore, we have a moral duty not to steal.

Kant also argues that there are two types of categorical imperatives: the hypothetical imperative and the categorical imperative. The hypothetical imperative is a rule of action that is contingent on some desire or end. For example, the hypothetical imperative "If I want to get to work on time, I should take the bus" is based on the desire to get to work on time.

The categorical imperative, on the other hand, is a rule of action that is not contingent on any desire or end. It is a rule that we should follow simply because it is right. For example, the categorical imperative "I should not lie" is a rule that we should follow simply because it is wrong to lie.

The Autonomy of the Will

Kant argues that the categorical imperative is based on the autonomy of the will. The autonomy of the will is the idea that we have the freedom to choose our own maxims, and that we are not determined by our desires or inclinations.

Kant argues that we have a moral duty to act in accordance with the categorical imperative because this is the only way to ensure that our actions are free and autonomous. If we act on the basis of our desires or inclinations, then our actions are not free, and therefore they are not moral.

The Critique of Practical Reason is one of Kant's most important works. It has had a profound influence on moral philosophy, and its ideas continue to be discussed and debated today.

Key Concepts

• Categorical imperative: A moral rule that we should follow simply because it is right.
• Hypothetical imperative: A rule of action that is contingent on some desire or end.
• Autonomy of the will: The idea that we have the freedom to choose our own maxims.

Quotes

• "Act only according to that maxim whereby you can, at the same time, will that it should become a universal law."
• "The only thing that is universally necessary is the existence of a rational being in the world ... in which the supreme practical law can be found."
• "Out of the crooked timber of humanity no straight thing was ever made."