John Stuart Mill wrote a famous (and short) book titled Utilitarianism. Mill differs from many current utilitarians in that he considered cultural and spiritual happiness to be of greater value than mere physical pleasure. In his essay On Liberty and other works, Mill argued that utilitarianism requires that political arrangements satisfy the "liberty principle", according to which each person must be guaranteed the greatest possible liberty that would not interfere with the liberty of others, so that each person may maximize his or her happiness. The classic utilitarianism of Bentham and Mill influenced many other philosophers and the development of the broader concept of consequentialism. As a result, the correct definitions of utilitarianism and consequentialism and the exact difference between these two principles are not always entirely clear, even among philosophers.
Immanuel Kant expressed extreme dissatisfaction with the consequentialist standard that may indicate that murder is wrong because it does not maximize good for the greatest number; but this would be irrelevant to someone who is not interested in maximizing the good. Consequently, Kant argued, hypothetical moral systems cannot persuade moral action or be regarded as bases for moral judgments against others, because the imperatives they are based on rely too heavily on subjective considerations.
"If A, then B," where A is a condition or goal, and B is an action. For example, if you wish to remain healthy, then you should not eat spoiled food.
Such a hypothetical imperative, according to Kant, is not justified in itself, but as a means to an end; whether it is in force as a command depends on whether the end it helps attain is desired (or required). The opposite of a hypothetical imperative is a categorical imperative, which is unconditional and an end in itself.
- "Act only according to that maxim by which you can at the same time will that it would become a universal law."
- "Act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end."
- "So act as though you were through your maxims a law-making member of a kingdom of ends."
In contrast to Hume, Kant viewed the human individual as a rationally autonomous self-conscious being with full freedom of action and self-determination. For a will to be considered "free", we must understand it as capable of effecting causal power without being caused to do so. But the idea of lawless free will, that is -- a will acting without any causal structure -- is incomprehensible. Therefore, a free will must be acting under laws that it gives to itself, and which are universally and objectively valid. Although Kant conceded that there could be no conceivable example of free will, because any example would only show us a will as it appears to us -- as a subject of natural laws -- he nevertheless argued against determinism. He proposed that determinism is logically inconsistent: The determinist claims that because A caused B, and B caused C, that A is the true cause of C. Applied to a case of the human will, a determinist would be arguing that the will does not have causal power because something else had caused the will to act as it did. But that argument merely assumes what it set out to prove; that the human will is not part of the causal chain.
Secondly, Kant remarks that free will is inherently unknowable. Since even a free person could not possibly have knowledge of his own freedom, we cannot use our failure to find a proof for freedom as evidence for a lack of it. The observable world could never contain an example of freedom because it would never show us a will as it appears to itself, but only a will that is subject to natural laws imposed on it. But we do appear to ourselves as free. Therefore he argued for the idea of transcendental freedom -- that is, freedom as a presupposition of the question "what ought I to do?" This is what gives us sufficient basis for ascribing moral responsibility: the rational and self-actualizing power of a person, which he calls moral autonomy: "the property the will has of being a law unto itself".
The Inquiring Murderer
One of the first major challenges to Kant's reasoning came from the Swiss philosopher Benjamin Constant, who asserted that since truth telling must be universal, according to Kant's theories, one must (if asked) tell a known murderer the location of his prey. This challenge occurred while Kant was still alive, and his response was the essay "On a Supposed Right to Tell Lies from Benevolent Motives." In this reply, Kant agreed with Constant, and argued that it is indeed one's moral duty to be truthful to a murderer.
Kant argued that telling the truth to the murderer is required because moral actions do not derive their worth from the expected consequences. He claimed that because lying to the murderer would treat him as a mere means to another end, the lie denies the rationality of another person, and therefore denies the possibility of there being free rational action at all. This lie results in a contradiction in conceivability and ergo the lie is in conflict with duty. Furthermore, Kant questioned our ability to know that the expected future outcomes of our actions would actually occur. For example, suppose Jim said that the victim was in the park, when he thought the target was in the library. However, unbeknownst to Jim, the victim actually left the library and went to the park. The lie would actually lead the murderer to the victim, which would make Jim responsible for the murder. Another example post-Kantians bring up is that one would not be morally responsible for the action anyway; the murderer would be. If one told the truth, it might turn out the murderer decides not to murder after all.