Is–ought problem

As Hume's Law (also humesches law or His - Shall - dichotomy ) is called a metaethisches principle that can not be closed by a being on an should or not be concluded logically from a lot of purely descriptive statements readily to normative or prescriptive statements can.

Hume's law refers to as a short title to an argument of the Scottish philosopher and historian David Hume ( 1711-1776 ). He emphasized that all known him Systems philosophical ethics of descriptive statements about what is (being) or is not, proceed to statements, what should be or should not be. However, both types of statements are quite diverse. A deduction from the former to the latter was simply incomprehensible.

" In every system of morality, which so far has met me, I've always found that the author proceeds for some time in the usual argumentation and establishes that there is a God, or makes observations about human behavior; then suddenly I realize surprised that instead of the usual set of links, namely, is 'and' is not ', I come only to sentences which with should ' or ' should not ' are connected. This change happens imperceptibly. However, it is very important. This should 'or' should not ' expresses a new link or assertion. Therefore, they must necessarily be observed and explained. At the same time necessarily a reason must be given for this, which seems completely incomprehensible: How namely this new shortcut can be a logical consequence of the other, of all different links ... I am convinced that such a minor attention would upset all the usual moral systems. It would also show us that the distinction of vice and virtue is not founded merely on the relations of objects, nor is it perceived by the senses. "

This ironic side note in A Treatise of Human Nature ( 1739-40 ), according to Hume's moral-philosophical contemporaries subject to a false conclusion. Readers are urged to carefully consider whether led an explanation or justification for their conclusions from descriptions on Sollensaussagen.

Hume founded his law with the division of consciousness into reason ( reason) and will. The task of reason is a match of belief and reality, in other words, the knowledge of truth. The will, however, is designed to shape reality according to the wishes and intentions and has a human action motivational component. The reason is not motivating force of will on the other hand is not directed by an objective truth.

Hume's separation of will and reason leads him to the conclusion that If a participation of the will presupposes, as it can have no action-guiding function otherwise. On the other hand, moral judgments, as they thus do not arise solely of reason, not reflected in the facts and not be completely brought with them to match. In everyday use ethical concepts and judgments include but occur in mixed form, prescriptive and descriptive content.

Hume's law is often interpreted as meaning that it prohibits the so-called naturalistic fallacy. Despite close relationship ( from both the inadmissibility of the conclusion of being on Shall follows ), the thesis of the naturalistic fallacy and Hume's Law to distinguish. Thus Hume's Law is a thesis about the logical structure of ethical reasoning forms, while the naturalistic fallacy is a thesis about the semantics of the adjective "good" is. This is namely indefinable and therefore not reducible to naturalistic terms. Hume's law stipulates that a transition from descriptive to normative statements by purely logical deductions is not possible; thus is not excluded that there are normative statements that associate natural properties value qualities or that there are normative statements that highlight particular Sollensaussagen under the condition of certain actual statements. When adding in such sentences ( bridge principles ) is quite a transition from being ready to being possible. However, he is just only legitimate if the normative, bridge used principle 'has already been recognized as valid. A legitimation of Shall ever is just out of the being that's not possible, but If only from others. After George Edward Moore such bridge principles are for the argument of the open question, however, inadmissible. Therefore, each transition from being to ought, he mainly naturalistic ethics, but also metaphysical ethics is subordinated For Moore, a naturalistic fallacy.

Skeptical consequence?

If one connects the His - Shall - issue with Hume's fork ( the idea that all knowledge areas either ( analytical ) logic and definitions or to ( empirical ) experience and observation based ), the validity of normative statements is questionable. If ought - statements can occur either in analytical or empirical sentences, so the consequence is that there is no moral knowledge. This problem led, among other things for moral skepticism and Nonkognitivismus.

David Hume himself saw the root of moral values ​​ultimately feeling and tradition. But he also noted that it was indifferent to humans, ultimately, what origin would have his moral convictions ( whether justified objectively, or only in his subjective view of the world ) as they for his behavior the same " reality " that is, the same action-guiding force possessed.

The criticism of Hume's Law attacks especially the delineation of normative and descriptive terms. In the momentous in the 20th century philosophy of law school of legal positivism, such as in the Pure Theory of Law by Hans Kelsen, however, the strict distinction between is and ought is required.