Categorical imperative

The categorical imperative is a moral concept developed by philosopher Immanuel Kant which states: "Act only according to that maxim whereby you can at the same time will that it become a universal law." The categorical imperative is an a priori moral commandment which is objective, and not based on circumstances. It is a deontological ethical construct, which is considered in opposition to consequentialistic schools of thought. It can be used both by the religious and the irreligious, but as Kant viewed reason as the source of morality, it rejects theological voluntarism.

Formulations
Kant also advanced other formulations of the categorical imperative which he considered to have the same meaning. The other formulations included:
 * "Act in such a way that you treat humanity, whether in your own person or in the person of any other, always at the same time as an end and never merely as a means to an end."
 * "Therefore, every rational being must so act as if he were through his maxim always a legislating member in the universal kingdom of ends."

The second formulation of the categorical imperative is the basis of the "social conscious" of Kant's theory, and is what the philosopher John Rawls based his ethical formulations on. This stands in sharp contrast to divine command theory, which has become the predominant form of deontological theory outside academia. Divine command theory posits that, instead, human beings are means for the achievement of divine ends.

Criticism
The categorical imperative largely leaves the decision of what rules ought to be universally implemented up to the individual, which has drawn much criticism from consequentialists who say that it is too subjective. Though Kant made it clear that the will to obey the categorical imperative is the only intrinsic good, the uncertainty of what the categorical imperative must consist of allows the doctrine to coexist, to some degree, with more objective ideas such as utilitarianism and intuitionism. Many creationists prefer the divine command theory or use that theory in concert with the categorical imperative because it allows them to more directly reject reason in favor of Goddidit than the categorical imperative alone.

Kantianism
Kantianism is the philosophical doctrine that is based on the teachings of Kant, specifically the categorical imperative and the principle that Man is an end and not just a means as well as transcendental idealism. Most deontologists also adhere to Kantianism. In recent times, Kantian philosophy has increasingly been replaced (within deontology) by divine command theory outside of academic circles, but Kant's ethical theories are within much of the academic work on ethics.