The fact-value distinction is a concept that distinguishes what is (can be discovered by science, philosophy, or reason) and what ought to be (a judgment agreed to by consensus, or believed to be objectively morally binding). The terms positive and normative represent another way to express this, as do the terms descriptive and prescriptive, respectively. Positive statements make the implicit claim to facts (e.g., water molecules are made of two hydrogen atoms and one oxygen atom), whereas normative statements make a claim based on values or norms (e.g., water ought to be protected from pollution).
 David Hume's skepticism
The fact-value distinction emerged in philosophy in the Enlightenment. In particular, David Hume (1711–1776) argued that human beings are unable to ground normative arguments in positive arguments, that is, to derive ought from is. Hume was a skeptic, and although he was a complex and dedicated philosopher, he shared a political viewpoint with previous Enlightenment philosophers such as Thomas Hobbes (1588–1679) and John Locke (1632–1704). Specifically, Hume, at least to some extent, argued that religious and national hostilities that divided European society were based on unfounded beliefs. In effect, he argued they are not found in nature, but are a creation of a particular time and place, and thus unworthy of mortal conflict. Thus Hume is often cited as the philosopher who finally debunked the idea of nature as a standard for political existence. For instance, without Hume, Jean Jacques Rousseau's (1712–1778) "return" to nature would have not been possible.
 Naturalistic fallacy
The fact-value distinction is closely related to the naturalistic fallacy, a topic debated in ethical and moral philosophy. G.E. Moore believed it essential to all ethical thinking. However, more recent contemporary philosophers like Phillipa Foot have called into question the validity of such assumptions. Others, such as Ruth Anna Putnam, argue that even the most "scientific" of disciplines are affected by the "values" of those who research and practice the vocation. Nevertheless, the difference between the naturalistic fallacy and the fact-value distinction is derived from the manner in which modern social science has used the fact-value distinction, and not the strict naturalistic fallacy to articulate new fields of study and create academic disciplines.
 Nietzsche's table of values
Friedrich Nietzsche (1844–1900) in Thus Spoke Zarathustra said that a table of values hangs above every great people. Nietzsche points out that what is common among different peoples is the act of esteeming, of creating values, even if the values are different from one people to the next. Nietzsche asserts that what made people great was not the content of their beliefs, but the act of valuing. Thus the values a community strives to articulate are not as important as the collective will to act on those values. The willing is more essential than the intrinsic worth of the goal itself, according to Nietzsche. "A thousand goals have there been so far," says Zarathustra, "for there are a thousand peoples. Only the yoke for the thousand necks is still lacking: the one goal is lacking. Humanity still has no goal." Hence, the title of the aphorism, "On The Thousand And One Goals". The idea that one value-system is no more worthy than the next, although it may not be directly ascribed to Nietzsche, has become a common premise in modern social science. Max Weber and Martin Heidegger absorbed it and made it their own. It shaped their philosophical endeavor, as well as their political understanding.
Virtually all modern Philosophers affirm some sort of fact-value distinction, insofar as they distinguish between science and "valued" disciplines such as ethics, aesthetics, or the fine arts. However, philosophers such as Richard Rorty argue that the distinction between fact and value is not as absolute as Hume envisioned. Philosophical pragmatists, for instance, believe that true propositions are those which useful or effective in predicting future (empirical) states of affairs. Far from being value-free, the pragmatic conception of truth directly relates to an end (namely, empirical predictability) that human beings regard as desirable. Other thinkers reject an absolutist fact-value distinction by contending that our senses are impregnated with prior conceptualizations, making it impossible to have any observation that is totally value independent, as the positivists implied.
 See also
- Putnam, Ruth Anna. "Perceiving Facts and Values," Philosophy 73, 1998. JSTOR 3752124 This article as well as her earlier article, "Creating Facts and Values," Philosophy 60, 1985 JSTOR 3750998, examines how scientists may base their choice of investigations on their unexamined subjectivity, which undermines the objectivity of their hypothesis and findings
- Smart, J.C. "Ruth Anna Putnam and the Fact-Value Distinction," Philosophy 74, 1999. JSTOR 3751844
- Nietzsche, Friedrich. Thus Spoke Zarathustra. Book Two "On the Virtuous": "You who are virtuous still want to be paid! Do you want rewards for virtue, and heaven for earth, and the eternal for your today? And now you are angry with me because I teach that there is no reward and paymaster? And verily, I do not even teach that virtue is its own reward."
- Nietzsche, Friedrich. Thus Spoke Zarathustra. Book Four "On Old and New Tablets": "To redeem what is past in man and to recreate all 'it was' until the will says, 'Thus I willed it! Thus I shall will it!' - this I called redemption and this alone I taught them to call redemption."
- Hume, David. A Treatise of Human Nature. First published 1739-1740.
- Hume, David. An Enquiry Concerning Human Understanding.
- Nietzsche, Friedrich. Thus Spoke Zarathustra. Translated by R.J. Hollingdale. New York: Penguin, 1969.
- Putnam, Hilary. The Collapse of the Fact/Value Dichotomy and Other Essays. Harvard University Press, 2002. ISBN 0-674-01380-8