Early intuitionism While there were ethical intuitionists in a broad sense at least as far back as
Thomas Aquinas, the philosophical school usually labelled as ethical intuitionism developed in Britain in the 17th and 18th centuries. Early intuitionists like
John Balguy,
Ralph Cudworth, and
Samuel Clarke were principally concerned with defending
moral objectivism against the theories of
Thomas Hobbes. Later, their views would be revived and developed by
Richard Price and pitted against the moral sense theory of
Francis Hutcheson, himself sometimes considered a sentimentalist intuitionist.
Immanuel Kant's moral philosophy would be received in Britain as a German analog to Price, though according to
R. M. Hare it is questionable whether Kant is an intuitionist.
Henry Sidgwick In the 19th century, ethical intuitionism was considered by most British philosophers to be a philosophical rival of
utilitarianism, until
Henry Sidgwick showed there to be several logically distinct theories, both normative and epistemological, sharing the same label. For Sidgwick, intuitionism is about intuitive, i.e. non-inferential, knowledge of moral principles, which are self-evident to the knower. The criteria for this type of knowledge include that they are expressed in clear terms, that the different principles are mutually consistent with each other and that there is expert consensus on them. According to Sidgwick, commonsense moral principles fail to pass this test, but there are some more abstract principles that pass it, like that "what is right for me must be right for all persons in precisely similar circumstances" or that "one should be equally concerned with all temporal parts of one’s life". The most general principles arrived at this way are all compatible with
utilitarianism, which is why Sidgwick sees a harmony between
intuitionism and
utilitarianism. There are also less general intuitive principles, like the duty to keep one's promises or to be just, but these principles are not universal and there are cases where different duties stand in conflict with each other. Sidgwick suggests that we resolve such conflicts in a utilitarian fashion by considering the consequences of the conflicting actions. Inspired by Sidgwick, 20th century philosopher
C. D. Broad would coin the term "
deontological ethics" to refer to the normative doctrines associated with intuitionism, leaving the phrase "ethical intuitionism" free to refer to the epistemological doctrines.
Intuitionism in analytic philosophy Ethical intuitionism was popular in the early twentieth century, particularly among British
analytic philosophers.
H. A. Prichard gave a defense of the view in his "
Does Moral Philosophy Rest on a Mistake?" (1912), wherein he contended that moral philosophy rested chiefly on the desire to provide arguments starting from non-normative premises for the principles of obligation that we pre-philosophically accept, such as the principle that one ought to keep one's promises or that one ought not to steal. This is a mistake, Prichard argued, both because it is impossible to derive any statement about what one ought to do from statements not concerning obligation (even statements about what is
good), and because there is no need to do so since common sense principles of moral obligation are self-evident. Prichard was influenced by
G. E. Moore, whose
Principia Ethica (1903) argued famously that
goodness was an indefinable, non-natural property of which we had intuitive awareness. Moore originated the term "
the naturalistic fallacy" to refer to the (alleged) error of confusing goodness with some natural property, and he deployed the Open Question Argument to show why this was an error. Unlike Prichard, Moore thought that one could derive principles of obligation from propositions about what is good.
W. D. Ross's intuitionism was influenced both by Prichard and Moore. He holds that we can know moral truths through intuition, for example, that it is wrong to lie or that knowledge is intrinsically good. Intuitions involve a direct apprehension that is not mediated by inferences or deductions: they are self-evident and therefore not in need of any additional proof. This ability is not inborn but has to be developed on the way to reaching mental maturity. But in its fully developed form, we can know moral truths just as well as we can know mathematical truths like the axioms of geometry or arithmetic. This self-evident knowledge is limited to general principles: we can come to know the
prima facie duties this way, e.g. that, generally speaking, one should keep one's promises and refrain from harming others. But intuition is unable to reveal one's
absolute duty in a particular situation: what one should do all things considered. All we can do is consult perception to determine which prima facie duty has the highest normative weight in this particular case, even though this usually does not amount to knowledge proper due to the complexity involved in most specific cases. Ethical intuitionism suffered a dramatic fall from favor by the middle of the century, due in part to the influence of
logical positivism, in part to the rising popularity of
naturalism in philosophy, and in part to philosophical objections based on the phenomenon of widespread moral disagreement.
C. L. Stevenson's
emotivism would prove especially attractive to Moorean intuitionists seeking to avoid
ethical naturalism. In the later parts of the 20th century, intuitionism would have few adherents to speak of; in
Bernard Williams' words: "This model of intuition in ethics has been demolished by a succession of critics, and the ruins of it that remain above ground are not impressive enough to invite much history of what happened to it."
Contemporary developments Some recent work suggests the view may be enjoying a resurgence of interest in academic philosophy.
Robert Audi is one of the main contemporary supporters of ethical intuitionism. His 2005 book
The Good in the Right claims to update and strengthen Rossian intuitionism and to develop the epistemology of ethics. Michael Huemer's book
Ethical Intuitionism (2005) also provides a recent defense of the view. Furthermore, authors writing on
normative ethics often accept
methodological intuitionism as they present allegedly obvious or intuitive examples or
thought experiments as support for their theories. ==Definitional issues==