William of Ockham (also known as Occam) (1285 – 1347/49)

William of Ockham was an English Franciscan monk, scholastic philosopher, theologian/apologist, and political writer. He may have died of the Black Death in 1348 or 1349.

In his controversial writings, William of Ockham appears as an advocate of secular absolutism, the principle that a secular government has absolute power and authority over its citizens. He denied the right of popes to exercise temporal power, or to interfere in any way whatever in the affairs of the Empire. Ockham was also a skeptic; he did not believe that one could explain philosophy’s deepest puzzles with certainty. In 1323, some members of the Franciscan Order found Ockham’s beliefs and writings to be dubious and brought him before the Franciscan provincial chapter to explicate himself. Although he was chastised, his views were not deemed heretical. In 1324, he was accused of heresy by an anonymous source and was summoned to the Papal court at Avignon to defend his views. In 1327, while in Avignon, the Franciscan Minister General, Michael of Cesena, arrived to address a theological conflict between the Franciscans, who believed and practiced “Apostolic poverty”, and the then pontiff, Pope John XXII who rejected that doctrine. In 1328, Michael and the pope clashed over this matter and Michael asked William of Ockham to review and comment on the particulars. Ockham reviewed three papal bulls and determined that the pope’s views were, in fact, heretical and, therefore, he had effectively abdicated his position as head of the church. Not surprisingly, this did not endear him to the pope and, under the cover of night on May 26, 1328, Ockham, Michael of Cesena and others fled to Italy where they sought the protection of Ludwig of Bavaria, the Holy Roman Emperor who, himself, was in a political dispute with the pope. Ockham was officially excommunicated on June 6, 1328, but not due to his political and theological views but because he had left Avignon in violation of the pope’s order [1].

Ockham’s razor (novacula Occami), or more precisely Ockham’s appeal to the law of parsimony (lex parsimoniae), was a metaphysical principle underlying his belief that elements of the world were simple as they had been created by God from first principles [2].Ockham’s use of the “razor” was a method by which he philosophically did away with “small entities” (res parvae) such as relation, motion, and action. The “razor” has become engrained in medicine, non-medical academia and popular culture and is often bantered about without the subtle understanding needed to apply it effectively and without knowledge of its origins or ample writings supporting or refuting its validity [3]. When asked as to its meaning, many reply that, “the simplest answer is usually the right one”. Others more familiar with the “razor” can quote one or another of Ockham’s purported statements in the original Latin – “Pluralitas non est ponenda sine necessitate” (A plurality is not to be posited without necessity) or “Frustra fit per plura quod potest fieri per pauciora” (It is useless to do with more what can be done with fewer).

The aphorism, “there is nothing new under the sun” is quite applicable when it comes to the law of parsimony. Aristotle (384–322 BC) in his Posterior Analytics wrote, “Other things being equal, we should prefer a demonstration which derives from fewer postulates or hypotheses.” This may be the earliest documented expression of the law of parsimony. Thomas Aquinas (1224/25 – 1274) recognized lex parsimoniae when he wrote in Summa Theologiæ, “It is superfluous to suppose that what can be accounted for by a few principles has been produced by many” [4]. The oldest Scholastic who expressed the axiom in a manner closest to the purported razor was Odo Rigaldus (or Rigaud) (c.1220–48), an early scholastic thinker in the thirteenth century whose version was “It is useless to explain by several things what can be explained by one” [5]. Alessandro Achillini (1463-1512), an Italian philosopher and physician, may have been the first physician to explicitly advocate and apply Ockham’s teachings [6]. However, the axiom “Entities should not be multiplied except out of necessity.” first appeared, with slight variation, in 1639 in the writings of John Ponce of Cork (1603–1661), an Irish theologian [7]. The maxim “Entities should not be multiplied except out of necessity” was first associated with Nominalism by Leibniz (1646 – 1716).  Isaac Newton (1642 – 1726/27), in his great work Principia Mathematica, acknowledged Ockham’s idea as the first rule of philosophical reasoning when he wrote, “We are to admit no more causes of natural things, than such as are both true and sufficient to explain their appearances.” In his ‘Critique of Pure Reason’, Immanuel Kant (1724 – 1804) accepted the law of parsimony as being inherent to pure reason but, interestingly, he balanced it with a qualifier, “The variety of beings should not rashly be diminished” (See Walter Chatton). Like Kant, Leibniz also believed that the law of parsimony should be balanced by a “Principle of Plenitude” which stated that the universe includes all possible forms of existence and affirms that everything that is rationally feasible is actual. In 1852, the English metaphysician, William Hamilton, was the first to label the law of parsimony as “Occam’s Razor” as he recognized that Ockham used it frequently and effectively in his arguments [8]. Closer to our time, Bertrand Russell (1872–1970) wished to limit the influence of metaphysics on logically based reasoning and adopted Occam’s razor to do so.

Surprisingly, in none of William of Ockham’s large body of writings are any of these axioms so stated, even though enumerable articles attribute them to him and, further, place them in quotation marks. Thorburn, writing in 1918 regarding Ockham’s purported razor, stated, “My own fruitless inquisition for the formula, in those works of Ockham which have been printed, has led me to doubt whether he ever used it to express his Critique of Entitities” [8]. That is not to say that Ockham was unaware of the essence and validity of the axiom which was well known in Medieval times. Indeed, it was an essential element in Ockham’s revolution in theology and philosophy and was Ockham’s favorite axiom. Ockham believed that logic and the theory of knowledge had been co-opted by metaphysics and theology, and he sought to disentangle them believing that “nature does nothing in vain”. Ockham’s teacher, John Duns Scotus, was well versed in lex parsimoniae and in his writings one can find “Plurality must never be posited without necessity” as well as “What can be done with fewer would in vain be done with more” [9].

The correct interpretation of the law of parsimony is that given two theories, with all other things being equal, and each theory equally plausible and capable of explaining a phenomenon, the theory with the fewest entities (variables) is preferable. As such, Occam’s razor should be used to distinguish between two theories, not two hypotheses. A theory needs to explain all the data whereas a hypothesis requires that data be collected in order to prove or disprove the theory. In clinical medicine, a differential diagnosis is best thought of as a hypothesis not a theory. In general, simpler explanations in science are preferrable to complex ones as they are more testable and easily falsified (as argued by Karl Popper). Importantly, one should apply the rule of “all things being equal” (ceteris paribus) whenever possible when comparing conflicting diagnoses so as to limit the number of intervening variables [7]. This was recognized by Aristotle who wrote, “We may assume the superiority ceteris paribus of the demonstration which derives from fewer postulates or hypotheses” [10]. Joseph Sapira added a further nuance with regards Occam’s razor. He stated that one can violate the razor if, “To do so, one of the causes must be a trait and the other must be a state. Each must be interactively necessary but singularly insufficient to produce the clinical picture” [11].

Walter Chatton (c. 1290–1343)

Walter Chatton was a Franciscan priest and a follower of Duns Scotus. His metaphysical leanings were, therefore, Scotistic and he defended Scotus’ doctrines. While at Oxford, Chatton was exposed to Ockham’s writings and philosophies and, in many instances, was opposed to them. After his training at Oxford was completed in 1330, he attained the status of Franciscan Regent master. The rest of his career was spent in Avignon. He served as advisor to Pope Benedict XII. Remarkably, not all of his writings have yet been translated

Ockham was a nominalist, the doctrine that universals or general ideas are simply names without any corresponding reality and that only particular objects exist [12]. To him, a universal concept is simply the act of thinking about several objects at once [13]. Ockham’s use of lex parsimoniae allowed him to reduce the number of basic ontological categories especially what he termed “res parvae” (small entities). In contrast to Ockham, Duns Scotus and Chatton were realists who viewed universals as substantive and that the properties of objects existed separately from the objects themselves, a Platonic view. Chatton believed that Ockham’s perspective could sometimes yield erroneous results; in particular, he argued that certain semantic arguments could reasonably prove the existence of a restricted class of relations (i.e., universals) [14].

In challenging Ockham’s reality of these and other entities, Chatton devised his own counter-principle or anti-razor which he referred to as propositio mea (‘my proposition’) and an ars responendi (‘a method of responding’), and simply regula mea (‘my rule’). His “rule” underwent several revisions in response to Ockham’s criticisms, but the final version declared, “where an affirmative proposition is made true by things (res), if fewer things (uniformly present, without anything else) cannot suffice [for that proposition’s being true], one must posit more” [15].

Chatton’s principle does not always apply very well to complex, multifarious theories, as is the case when diagnosing complicated, multisymptomatic patients. In those circumstances, one is not necessarily striving to attain a unified, explanatory theory/proposition but to disentangle the various signs and symptoms of a patient’s presentation into the fewest number of diagnoses that effectively explain all of them. (See Hickam)

John Bamber Hickam (1914 – 1970)

Given the wording of Hickam’s dictum, “A patient can have as many diseases as he damn well pleases”, one could be excused for believing that Dr. Hickam was a crusty, country doctor who simply had a deep insight into clinical diagnosis. John Bamber Hickam, however, was a highly accomplished and respected academic clinician and researcher. He graduated summa cum laude from Harvard College and cum laude from Harvard University School of Medicine. He ascended to the chairmanship of the Department of Medicine at Indiana University in 1958 and was widely recognized for his expertise in cardiorespiratory physiology. At Indiana University he pioneered new methods in medical education, and under his guidance, Indiana University developed one of the most innovative medical curricula in the country [16]. While “Hickam’s dictum” is well accepted and frequently expressed in both medical and non-medical writings, nowhere can one find a primary, reputable reference of Dr. Hickam having written or uttered those words. Those who had known Dr. Hickam, however, believe that the dictum, in content and style, is very much in keeping with his approach to clinical diagnosis (oral communication). It is not known whether Dr. Hickam was familiar with Chatton’s “anti-razor”. It is important to note that Hickam’s dictum is not an “all or none” proposition. One can first apply Occam’s razor and, failing to adequately diagnose a patient, resort to Hickam’s dictum.

References

1. “William of Ockham”. E Zalta (Ed.). The Stanford Encyclopedia of Philosophy. Winter 2018 ed. Stanford University. https://plato.stanford.edu/entries/ockham/.

2. Dolezal, JE. “The Simplicity of God.” Tabletalk 42, no. 5 (2018): 72–75. https://tabletalkmagazine.com/article/2018/05/the-simplicity-of-god/

3. Ariew, R. “Did Ockham use his razor?” Franciscan Studies 37 (1977): 5–17. https://www.jstor.org/stable/41974817

4. D. Thomas Aquinas, Summa Theologiae, Vol. II, McGraw-Hill (N.Y., 1963), p. 13. https://ia601306.us.archive.org/21/items/SummaTheologicaThomasAquinas/Summa%20Theologica%2C%20Thomas%20Aquinas.pdf

5. Maurer, A (1984). Ockham’s razor and Chatton’s anti-razor. Mediaeval Studies 46 (1):463-475. https://doi.org/10.1484/j.ms.2.306670         

6. The Editors of Encyclopaedia Britannica. “Alessandro Achillini”. Encyclopedia Britannica, 25 Oct. 2024, https://www.britannica.com/biography/Alessandro-Achillini.

7. Matsen, HS. Alessandro Achillini (1463-1512) and His Doctrine of” universals” and” transcendentals”: A Study in Renaissance Ockhamism. Associated University Presse, 1974. 332 pp. https://www.google.com/books/edition/Alessandro_Achillini_1463_1512_and_His_D/cV9IqlBv83MC?hl=en&gbpv=1&dq=Study+in+Renaissance+Ockhamism.+Lewisburg:+Bucknell+University+Press,+1974&pg=PA3&printsec=frontcover

8. Thorburn, WM. “The Myth of Occam’s Razor.” Mind. 1918, (27): 345-53. 10.1093/mind/XXVII.3.345

9. Ariew, R. “Did Ockham use his razor?.” Franciscan Studies 37.1 (1977): 5-17. https://doi.org/10.1353/frc.1977.0007

10. Aristotle, Posterior Analytics, I,c.25, 86a33. https://www.logoslibrary.org/aristotle/posterior/125.html

11. Sapira JD. On violating Occam’s razor. South Med J. 1991;84:766. doi: 10.1097/00007611-199106000-00023

12. Brower-Toland, S. “Walter Chatton.” In Encyclopedia of Medieval Philosophy: Philosophy Between 500 and 1500, ed. Henrik Laugerlund (Dordrecht: Springer). https://www.academia.edu/16365982/_Walter_Chatton_in_Henrik_Laugerlund_ed_Encyclopedia_of_Medieval_Philosophy_Philosophy_Between_500_and_1500_Springer_2011_

13. Matteo, AM. “Scotus and Ockham: A Dialogue on Universals.” Franciscan studies 45, no. 1 (1985): 83-96. https://www.jstor.org/stable/41975048

14. Gamboa L, Ockham and Lydia D. “William of Walter Chatton on self-knowledge.” (2016). https://archipel.uqam.ca/17042/

15. Maurer, A. “Ockham’s razor and Chatton’s anti-razor.” Mediaeval Studies 46, no. 1 (1984). https://doi.org/10.1484/j.ms.2.306670

16. M.D.B. John Bamber Hickam. Arch Intern Med. 1971;127(4):569–570. doi:10.1001/archinte.1971.00310160047003