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The is–ought problem is a philosophical problem of how knowledge of the present world does not necessarily lead to knowledge of how the world ought to be. This is also sometimes referred to as Hume's law or "Hume's Guillotine".
Hume's is-ought distinction
In every system of morality, which I have hitherto met with, I have always remark'd, that the author proceeds for some time in the ordinary ways of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when all of a sudden I am surpriz'd to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, 'tis necessary that it shou'd be observ'd and explain'd; and at the same time that a reason should be given; for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it.
The is-ought problem has become prominent in matters of ethics and meta-ethics. Simply put, it deals with an apparent logic gap between statements of what "ought" to be, following statements regarding what "is". The first often following the second without any kind of explanation regarding why they are logical or correct.
Furthermore, it argues that just because someone has knowledge of how the world is (descriptive statements), this doesn't automatically prove that they know how the world ought to be (prescriptive statements) and it is in fact impossible to derive the second based solely on the information of the first.
One example that comes up occasionally from certain people goes as follows: Sex is for reproduction, therefore people shouldn't be having sex outside of marriage/shouldn't be having homosexual sex/should only use sex to make a baby. In this case Hume's Law is a good tool for pointing out that, while technically it may be correct that sex is for reproduction, it can also be for other things, and a person arguing differently would need to provide additional arguments for why it ought not be used in ways beyond its alleged "natural purpose".
A number of attempts have been made to solve the is-ought problem, usually involving some type of invocation of natural law. One mode of attack has been to resurrect a form of Aristotelian teleology. Another approach was John Searle's definition of social obligations as "institutional facts", thus allowing is to be derived from ought. The linked source is a dissertation from an obscure thinker which claims that none of these approaches have gained widespread support as a solution to the problem, but it is from 2010, and further research is recommended to the reader.
A simple solution is through the addition of a goal to the formulation. The problem can therefore be bypassed with a simple if: "If you want to achieve goal X, you should do Y which has been shown to lead to X." Sam Harris espouses a view similar to this when dealing with the issue of morality, but one that would generally need two additions rather than one: "If morality has to deal with not causing the suffering of conscious creatures, and if you want to live a moral life, you should take actions that don't cause the suffering of conscious creatures." This hinges on accepting this as a definition of morality, whereas some would claim that there is no reason to accept that morality should or could be defined in this (utilitarian or consequentialist) manner, however these same people would probably be using a very abstract (or possibly none at all) definition of morality where morality cannot be defined as long as the universe lacks overall "objective" purpose. A glaring weakness in Harris' approach is that he essentially inserts an ought as a premise (barely obscured inside a conditional), thereby completely missing the target, which would be to derive an ought only from premises in the form of "is" - providing an ought of one's own is exactly the kind of miserable nonsense Hume originally indicted.
The concept of non-overlapping magisteria has been advocated by Stephen Jay Gould. This is the idea that science and religion are not in inherent conflict as they contribute to different areas of human existence and give meaning to life in different ways. Richard Dawkins criticizes Gould's position saying "it is completely unrealistic to claim, as Gould and many others do, that religion keeps itself away from science's turf, restricting itself to morals and values. A universe with a supernatural presence would be a fundamentally and qualitatively different kind of universe from one without. The difference is, inescapably, a scientific difference. Religions make existence claims, and this means scientific claims."
Albert Einstein held a similar view as Gould, but he was smarter about it (because, well, he was Einstein). Einstein argued that science concerns itself with the what is side of Hume's law and religion concerned itself with what ought.
“”If one conceives of religion and science according to these definitions then a conflict between them appears impossible. For science can only ascertain what is, but not what should be, and outside of its domain value judgments of all kinds remain necessary. Religion, on the other hand, deals only with evaluations of human thought and action: it cannot justifiably speak of facts and relationships between facts.
So how is this position any different than Gould's? Well Einstein redefined religion to make the conflict impossible. As he said in the quote above, religion cannot justifiably speak of facts and relationships between facts. He repeats this viewpoint in other writings and makes it clear in no uncertain terms that religion should not intrude on science's domain.
“”It is this mythical, or rather this symbolic, content of the religious traditions which is likely to come into conflict with science. This occurs whenever this religious stock of ideas contains dogmatically fixed statements on subjects which belong in the domain of science. Thus, it is of vital importance for the preservation of true religion that such conflicts be avoided when they arise from subjects which, in fact, are not really essential for the pursuance of the religious aims.
Thus there is no conflict between religion and science as religions that intrude on the what is side of Hume's law are simply false religions. Problem solved... at least from Einstein's perspective. The issue is, of course, that most people don't adhere to Einstein's definition of religion and therefore the conflict between religion and science remains intact.
A naturalistic fallacy occurs when one fallaciously derives an "ought" from an "is", i.e., where one claims that the way things often are is how they should be. For example, a naturalistic fallacy would be "humans have historically been bigots, therefore bigotry is moral", or "humans and other animals often fight over territory or resources or mating rights, therefore frequent violence is moral".
The inversion of the "is-ought" into "ought-is" is the moralistic fallacy. That is, if something "ought to be", it "is", i.e., if you think something is moral it must be natural. An example is "bigotry is bad, therefore bigotry is not in human nature", instead of the more realistic "bigotry is bad, therefore humans should work to overcome their bigoted nature".
The is-ought distinction is sometimes misconstrued to mean that facts are totally disconnected from ethical statements, or that there is no relationship at all between is and ought. As can be seen, Hume does not argue this position, but states that a factual statement (or "is") needs to be combined with an ethical principle or assumption before an ethical statement (or "ought") can be derived.
- Appeal to ancient wisdom
- Appeal to nature: The fallacy which states "X is natural, therefore X is good," sometimes misidentified as the naturalistic fallacy.
- Appeal to tradition
- Just world hypothesis
- Social Darwinism
- Essay:The religious views of Albert Einstein
- False consciousness — the Marxist version
- See the Wikipedia article on Naturalistic fallacy.
- Hume's Guillotine, Philosophy Index
- Naturalistic Fallacy, Stanford Encyclopedia of Philosophy
- Hume's Guillotine, Julia Galef, Rationally Speaking
- A Treatise on Human Nature, Volume II, Book III
- Stilley, Shalina, "Natural Law Theory and the "Is"--"Ought" Problem: A Critique of Four Solutions" (2010). Dissertations (2009 -). Paper 57.
- Einstein's Ideas and Opinions, pp.41 - 49
- The Christian Register, June, 1948
- David Sloan Wilson, Eric Dietrich, and Ann B. Clark. On the Inappropriate Use of the Naturalistic Fallacy in Evolutionary Psychology. Biology and Philosophy, 18: 669-682, 2003.