From New World Encyclopedia

Casuistry (pronounced /ˈkæʒuːɨstri/) is an applied ethics term referring to case-based reasoning. Casuistry is used in juridical and ethical discussions of law and ethics, and often is a critique of principle-based reasoning.

Critics use the term pejoratively for the use of clever but unsound reasoning, especially in relation to moral questions (such as in Sophistry). In the twentieth century, Albert Jonsen and Stephen Toulmin revived the philosophical importance of casuistry as a situation-based reasoning in their work, The Abuse of Casuistry: A History of Moral Reasoning (1988). Straightforward traditional principle-based moral reasoning does not necessarily apply to many real legal and moral cases due to their complexity. Casuistry is studied today in various fields of applied ethics.


Casuistry is a method of case reasoning especially useful in treating cases that involve moral dilemmas. It is also a branch of applied ethics. Casuistry is the basis of case law in common law, and the standard form of reasoning applied in common law.[1]


For example, while a principle-based approach might claim that lying is always morally wrong, the casuist would argue that, depending upon the details of the case, lying may or may not be illegal or unethical. For instance, the casuist might conclude that a person is wrong to lie in legal testimony under oath, but might argue that lying actually is the best moral choice if the lie saves a life (Thomas Sanchez and others thus theorized a doctrine of mental reservation). For the casuist, the circumstances of a case are essential for evaluating the proper response.

Typically, casuistic reasoning begins with a clear-cut paradigmatic case (from paradigm, the Greek word παράδειγμα, paradeigma, "pattern" and "example," in turn derived from παραδεικνύναι paradeiknunai, "demonstrate"). In legal reasoning, for example, this might be a precedent case, such as premeditated murder. From it, the casuist would ask how closely the given case currently under consideration matches the paradigmatic case. Cases like the paradigmatic case ought to be treated likewise; cases unlike the paradigm ought to be treated differently. Thus, a man is properly charged with premeditated murder if the circumstances surrounding his case closely resemble the exemplar premeditated murder case. The less a given case is like the paradigm, the weaker the justification is for treating that case like the paradigmatic case.



Western casuistry dates from Moses and Aristotle (384–322 B.C.E.), yet the zenith of casuistry was from 1550 to 1650 C.E., when the Jesuit religious order extensively used casuistry, particularly in practicing the private, Roman Catholic confessional. The term casuistry quickly became pejorative with Blaise Pascal's attack on its misuse. In Provincial Letters (1656–7)[2] he scolded the Jesuits for using casuistic reasoning in confession to placate wealthy Church donors, whilst punishing poor penitents. Pascal charged that aristocratic penitents could confess their sins one day, recommit the sin the next day, generously donate the following day, then return to re-confess their sins and only receive the lightest punishment; Pascal's criticisms darkened casuistry's reputation. Since the seventeenth century, casuistry has been widely considered a degenerate form of reasoning. Critics of casuistry focus on its specious argumentation as intentionally misleading.

It was not until publication of The Abuse of Casuistry: A History of Moral Reasoning (1988), by Albert Jonsen and Stephen Toulmin,[3] that a revival of casuistry occurred. They argue that the abuse of casuistry is the problem, not casuistry itself (in itself an example of casuistic reasoning). Properly used, casuistry is powerful reasoning. Jonsen and Toulmin offer casuistry in dissolving the contradictory tenets of absolutism and relativism: “The form of reasoning constitutive of classical casuistry is rhetorical reasoning.”[4] Moreover, Utilitarianism and Pragmatism commonly are identified as philosophies employing the rhetorical reasoning of casuistry.

Casuistry in early modern times

The casuistic method was popular among Catholic thinkers in the early modern period, and not only among the Jesuits, as it is commonly thought. Famous casuistic authors include Antonio Escobar y Mendoza's Summula casuum conscientiae (1627), which had enjoyed a great success, Thomas Sanchez, Vincenzo Filliucci (Jesuit and penitentiary at St Peter's), Antonino Diana, Paul Laymann (Theologia Moralis, 1625), John Azor (Institutiones Morales, 1600), Etienne Bauny, Louis Cellot, Valerius Reginaldus, Hermann Busembaum (d. 1668), and so on. One of the main theses of casuists was the necessity to adapt the rigorous morals of the Early Fathers of Christianity to modern morals, which led in some extreme cases to justify what Innocent XI later called "laxist moral" (that is, justification of usury, homicide, regicide, lying through "mental reservation," adultery and loss of virginity before marriage, and so on—all due cases registered by Pascal in the Provincial Letters).

The progress of casuistry was interrupted towards the middle of the seventeenth century by the controversy which arose concerning the doctrine of probabilism, which stipulated that one could choose to follow a "probable opinion," that is, supported by a theologian or another, even if it contradicted a more probable opinion or a quotation from one of the Fathers of the Church. The controversy divided Catholic theologians into two camps, Rigorists and Laxists.

Casuistry was much mistrusted by early Protestant theologians, because it justified many of the abuses that they sought to reform. It was famously attacked by the Catholic and Jansenist philosopher Pascal, during the formulary controversy against the Jesuits, in his Provincial Letters as the use of rhetorics to justify moral laxity, which became identified by the public with Jesuitism; hence the everyday use of the term to mean complex and sophistic reasoning to justify moral laxity. By the middle of the eighteenth century, the name of "casuistry" became a synonym of moral laxity.

In 1679, Pope Innocent XI publicly condemned sixty-five of the more radical propositions (stricti mentalis), taken chiefly from the writings of Escobar, Suarez and other casuists as propositiones laxorum moralistarum and forbade anyone to teach them under penalty of excommunication.[5] Despite this papal condemnation, both Catholicism and Protestantism permit the use of ambiguous and equivocal statements in specific circumstances.[6]

Alphonsus Maria de Liguori (d. 1787), founder of the Congregation of the Most Holy Redeemer, then brought some attention back to casuistry by publishing again Hermann Busembaum's Medulla Theologiae Moralis, the last edition of it being published in 1785 and receiving the approbation of the Holy See in 1803. Busembaum's Medulla had been burnt in Toulouse in 1757, because of its justification of regicide, deemed particularly scandalous after Damiens' assassination attempt against Louis XV.

Casuistry in modern times

In modern times, casuistry has successfully been applied to law, bioethics, and business ethics, and its reputation is somewhat rehabilitated. G.E. Moore dealt with casuistry in chapter 1.4 of his Principia Ethica; he claimed that "the defects of casuistry are not defects of principle; no objection can be taken to its aim and object. It has failed only because it is far too difficult a subject to be treated adequately in our present state of knowledge." He also asserted, "Casuistry is the goal of ethical investigation. It cannot be safely attempted at the beginning of our studies, but only at the end."[7]

A good reference, analyzing the methodological structure of casuistic argument is The Abuse of Casuistry: A History of Moral Reasoning (1990), by Albert Jonsen and Stephen Toulmin.

The casuist morality

Casuistry takes a relentlessly practical approach to morality. Rather than using theories as starting points, casuistry begins with an examination of cases. By drawing parallels between paradigms, so called "pure cases," and the case at hand, a casuist tries to determine a moral response appropriate to a particular case.

Casuistry has been described as "theory modest.". One of the strengths of casuistry is that it does not begin with, nor does it overemphasize, theoretical issues. Casuistry does not require practitioners to agree about ethical theories or evaluations before making policy. Instead, they can agree that certain paradigms should be treated in certain ways, and then agree on the similarities, the so-called warrants between a paradigm and the case at hand.

Since most people, and most cultures, substantially agree about most pure ethical situations, casuistry often creates ethical arguments that can persuade people of different ethnic, religious and philosophical beliefs to treat particular cases in the same ways. For this reason, casuistry is widely considered to be the basis for the English common law and its derivatives.

Casuistry is prone to abuses wherever the analogies between cases are false.


Casuists have often been mistrusted as too self-serving, and their reasoning thought too inaccessible. The reasoning is often inaccessible because successful casuistry requires a large amount of knowledge about paradigms, and how parallels can be drawn from those paradigms to real life situations. In modern times, there is a similar tremendous resentment against lawyers and law. Defenders of casuistry often point out that the problems are not so much with casuistry itself, but with the improper use of casuistry. That these problems manifest themselves so often however may make it appear to some that this form of reasoning is somewhat easier to misuse than it is to apply correctly.


  1. Dictionary of the History of Ideas, Casuistry, University of Virginia Library. Retrieved June 18, 2008.
  2. Blaise Pascal, The Provincial Letters of Blaise Pascal, translated by Thomas M'Crie (London: Chatto & Windus, 1898). Retrieved June 18, 2008.
  3. Albert Jonsen and Stephen Toulmin, The Abuse of Casuistry: A History of Moral Reasoning (Berkeley: University of California Press, 1990, ISBN 0-520-06960-9).
  4. Jonsen (1990), p. 297.
  5. J.N.D. Kelly, The Oxford History of the Popes (Oxford University Press, 1986, ISBN 0192820850), p. 287.
  6. J.-P. Cavaillé, Ruser sans mentir, de la casuistique aux sciences sociales: le recours à l’équivocité, entre efficacité pragmatique et souci éthique, in Serge Latouche, P.-J. Laurent, O. Servais & M. Singleton, Les Raisons de la ruse. Une perspective anthropologique et psychanalytique (Paris: La Découverte, 2004), p. 93–118. Retrieved June 18, 2008.
  7. G.E. Moore, Principia Ethica, 2nd edition (New York: Cambridge University Press, 1993, ISBN 0521448484), p. 57. Retrieved June 18, 2008.

ISBN links support NWE through referral fees

  • Bedau, Hugo Adam. Making Mortal Choices Three Exercises in Moral Casuistry. New York: Oxford University Press, 1997. ISBN 0585363897.
  • Cavaillé, J.-P. Ruser sans mentir, de la casuistique aux sciences sociales : le recours à l’équivocité, entre efficacité pragmatique et souci éthique. In Serge Latouche, P.-J. Laurent, O. Servais & M. Singleton. Les Raisons de la ruse. Une perspective anthropologique et psychanalytique. Paris: La Découverte, 2004. p. 93–118. Retrieved June 18, 2008.
  • Jonsen, Albert, and Stephen Toulmin, The Abuse of Casuistry: A History of Moral Reasoning. Berkeley: University California Press, 1990. ISBN 0-520-06960-9.
  • Keenan, James F., and Thomas A. Shannon. The Context of Casuistry. Washington, D.C.: Georgetown University Press, 1995. ISBN 0878405852.
  • Kirk, Kenneth E. Conscience and Its Problems An Introduction to Casuistry. Louisville, Ky: Westminster John Knox Press, 1999. ISBN 0585388458.
  • Latouche, Serge, P.-J. Laurent, O. Servais, and M. Singleton, Les Raisons de la ruse. Une perspective anthropologique et psychanalytique. Paris: La Découverte, 2004.
  • Moore, G.E. Principia Ethica. New York: Cambridge U. Press, 1993. ISBN 0521448484. Retrieved June 18, 2008.
  • Pascal, Blaise. The Provincial Letters of Blaise Pascal. Translated by Thomas M'Crie. London: Chatto & Windu, 1898. Retrieved June 18, 2008.
  • Slights, Camille Wells. The Casuistical Tradition in Shakespeare, Donne, Herbert, and Milton. Princeton, N.J.: Princeton University Press, 1981. ISBN 0691064636.
  • Starr, G.A. Defoe & Casuistry. Princeton, N.J.: Princeton University Press, 1971. ISBN 0691061920.
  • University of Virginia Library. Casuistry. Dictionary of the History of Ideas. Retrieved June 18, 2008.

External links

All links retrieved November 29, 2023.

General philosophy sources


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