Explain the most important differences between Kantian ethics and utilitarianism.
The most important difference between the two schools of ethics lies in the respective weight they give to moral actions and their consequences. Kantianism is what's called a deontological ethical theory. This rather complicated looking word simply means that which is related to duty. Kant's ethical theory is traditionally defined as deontological because it is a duty-based ethic, one that focuses on the nature of individual moral actions rather than their consequences. For Kant, what makes a moral action moral is its conformity to duty, a duty that we give to ourselves in accordance with reason.
This particular feature of Kant's thought puts him at odds with consequentialist theories such as utilitarianism, which focuses instead on the consequences of moral actions. Unlike the Kantian, the utilitarian doesn't ask herself whether a specific moral action is intrinsically right or wrong, or rational, or is being carried out according to duty, but whether the consequences will be beneficial to society as a whole. Or, to use the famous felicific calculus, whether it leads to the greatest happiness of the greatest number.
For the utilitarian moral evaluation comes after the fact, and even then it comes from society rather than the individual. It's only once the impact on society's general level of happiness has been assessed that one can safely declare that a certain action is morally good or bad.
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