Akrasia
Akrasia (; Greek ἀκρασία, "lacking command" or "weakness", occasionally transliterated as acrasia or Anglicised as acrasy or acracy) is a lack of self-control or acting against one's better judgment. It is sometimes translated into English as incontinence ("a want of continence or self-restraint"). Beginning with Plato, a variety of philosophers have attempted to determine whether or not akrasia exists and how best to define it.

History
In Plato's Protagoras dialogue, Socrates asks precisely how it is possible that, if one judges action A to be the best course of action, why would one do anything other than A?

Classical answers
Plato's Socrates attests that akrasia does not exist, claiming "No one goes willingly toward the bad" (358d). If a person examines a situation and decides to act in the way he determines to be best, he will pursue this action, as the best course is also the good course, i.e. man's natural goal.  An all-things-considered assessment of the situation will bring full knowledge of a decision's outcome and worth, linked to well-developed principles of the good. A person, according to Socrates, never chooses to act poorly or against his better judgment and therefore, actions that go against what is best are simply a product of being ignorant of facts or knowledge of what is best or good.
Aristotle, acknowledging that we intuitively believe in akrasia, devoted book VII of the Nicomachean Ethics to a more empirical approach to the question. He distanced himself from the Socratic position by arguing that akrasia occurs as a result of an agent's opinion, not of their desire. Since opinion is formulated mentally in a way that may or may not imitate truth, while appetites are merely desires of the body, opinion is only incidentally aligned with or opposed to the good, making an akratic action the product of opinion instead of reason. For Aristotle, the opposite of akrasia is enkrateia a state where an agent has power over their desires. Aristotle considered one could be in a state of akrasia with respect to money or temper or glory, but that its core relation was to bodily enjoyment. Its causes could be weakness of will, or an impetuous refusal to think. At the same time he did not consider it a vice because it is not so much a product of moral choice but a failure to act on one's better knowledge.For Augustine of Hippo, incontinence was not so much a problem of knowledge (knowing but not acting) but of the will; he considered it a matter of everyday experience that men incontinently choose lesser over greater goods.

Contemporary approaches
Donald Davidson (1969–1980) attempted to answer the question by first criticizing earlier thinkers who wanted to limit the scope of akrasia to agents who despite having reached a rational decision were somehow swerved off their "desired" tracks.  Indeed, Davidson expands akrasia to include any judgment that is reached but not fulfilled, whether it be as a result of an opinion, a real or imagined good, or a moral belief. "[T]he puzzle I shall discuss depends only on the attitude or belief of the agent...my subject concerns evaluative judgments, whether they are analyzed cognitively, prescriptively, or otherwise."  Thus, he expands akrasia to include cases in which the agent seeks to fulfill desires, for example, but end up denying themselves the pleasure they have deemed most choice-worthy.
Davidson sees the problem as one of reconciling the following apparently inconsistent triad:

If an agent believes A to be better than B, then they want to do A more than B.
If an agent wants to do A more than B, then they will do A rather than B if they only do one.
Sometimes an agent acts against their better judgment.Davidson solves the problem by saying that, when people act in this way they temporarily believe that the worse course of action is better because they have not made an all-things-considered judgment but only a judgment based on a subset of possible considerations.
Another contemporary philosopher, Amélie Rorty (1980) has tackled the problem by distilling out akrasia's many forms.  She contends that akrasia is manifested in different stages of the practical reasoning process. She enumerates four types of akrasia: akrasia of direction or aim, of interpretation, of irrationality, and of character.  She separates the practical reasoning process into four steps, showing the breakdown that may occur between each step and how each constitutes an akratic state.
Another explanation is that there are different forms of motivation which can conflict with each other. Throughout the ages, many have identified a conflict between reason and emotion, which might make it possible to believe that one should do A rather than B, but still end up wanting to do B more than A.
Psychologist George Ainslie argues that akrasia results from the empirically verified phenomenon of hyperbolic discounting, which causes us to make different judgements close to a reward than we will when further from it.

Weakness of will
Richard Holton (1999), argues that weakness of the will involves revising one's resolutions too easily. Under this view, it is possible to act against one's better judgment (that is, be akratic), but without being weak-willed. Suppose, for example, Sarah judges that taking revenge upon a murderer is not the best course of action but makes the resolution to take revenge anyway and sticks to that resolution.  According to Holton, Sarah behaves akratically but does not show weakness of will.

Legacy
In the structural division of Dante's Inferno, incontinence is the sin punished in the second through fifth circles. The mutual incontinence of lust was for Dante the lightest of the deadly sins, even if its lack of self-control would open the road to deeper layers of Hell.
Akrasia appeared later as a character in Spenser's The Faerie Queene, representing the incontinence of lust, followed in the next canto by a study of that of anger; and as late as Jane Austen the sensibility of such figures as Marianne Dashwood would be treated as a form of (spiritual) incontinence.With the triumph of Romanticism, however, the incontinent choice of feeling over reason became increasingly valorised in Western culture. Blake wrote that "those who restrain desire, do so because theirs is weak enough to be restrained". Encouraged by Rousseau, there was a rise of what Arnold J. Toynbee would describe as "an abandon (ακρατεια)...a state of mind in which antinomianism is accepted – consciously or unconsciously, in theory or in practice – as a substitute for creativeness".A peak of such acrasia was perhaps reached in the 1960s cult of letting it all hang out – of breakdown, acting out and emotional self-indulgence and drama. Partly in reaction, the proponents of emotional intelligence would look back to Aristotle in the search for impulse control and delayed gratification – to his dictum that "a person is called continent or incontinent according as his reason is or is not in control".

See also
Notes
References
Further reading
Dahl, N.O. 1984. Practical Reason, Aristotle, and the Weakness of Will. Minneapolis: University of Minnesota Press.
Wedin, M. 1988. Mind and Imagination in Aristotle. New Haven: Yale University Press.
Hookway, C. (2001). "Epistemic Akrasia and Epistemic Virtue". In Fairweather, A.; Zagzebski, L. (eds.). Virtue Epistemology: Essays on Epistemic Virtue and Responsibility. Oxford: Oxford University Press. pp. 178–199. ISBN 978-0-19-514077-4.
Schorsch, A.J. (1992). Housing Policy and Common Sense: An Inquiry and a Method (PDF) (Thesis/Dissertation ed.). University of Illinois at Chicago. pp. 85–90.{{cite book}}:  CS1 maint: location missing publisher (link)
Searle, J.R. (2001). Rationality in Action. Cambridge: MIT Press. ISBN 978-0-262-19463-1.
Stroud, Sarah (2008). "Weakness of Will". In Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy (Fall ed.). Metaphysics Research Lab, Stanford University.
Valverde, M. (1998). Diseases of the Will: Alcohol and the Dilemmas of Freedom. Cambridge: Cambridge University Press. ISBN 978-0-521-62300-1.
Wegner, D.M. (2002). The Illusion of Conscious Will. Cambridge: MIT Press. ISBN 978-0-262-23222-7.

External links

"Akrasia" by Seth J. Chandler, The Wolfram Demonstrations Project, 2007: An interactive computer model of akrasia based on Cooter, R.; Ulen, T. (2007). Law and Economics (5th ed.). Boston: Addison Wesley.
Akrasia and Self-Binding.
Daniel Wegner's site containing links to papers on conscious will and on thought suppression.
Aristotle: Ethics and the Virtues (Weakness of the Will)
Aristotle: Nicomachean Ethics, Book VII