From Philosophy to Practice. Critical reasoning in the oncological practice
Author:
Giovanni Boniolo
Date of publication: 03 April 2025
Last update: 03 April 2025
Abstract
On April 6, 2016, Richard Smith, former editor of “The British Medical Journal”, wrote a surprising note titled “Medicine’s need for philosophy”. In this entry it is told why medicine in general and oncology in particular need a special branch of philosophy, that is, critical thinking.
Why critical thinking?
On April 6, 2016, Richard Smith, former editor of “The British Medical Journal”, wrote a surprising note titled “Medicine’s need for philosophy” (Smith 2016). After some reflection on the status of medical education and clinical practice, he concluded that “I came away with a conviction that healthcare, which is suffering an existential crisis, badly needs the help of philosophers”. A year before, Robert Casadevall, a microbiologist and immunologist at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, burst onto the scene of the American way of teaching medicine claiming, in the “Johns Hopkins Public Health Magazine”, that there is the need “[To] Put the ‘Ph’ Back in PhD”, where ‘Ph’ was for ‘Philosophy’, since “We need big thinkers, but the current system teaches students to think small”.
Both Casadevall and Smith did not mean to introduce Aristotle, Plato, Hegel, or Nietzsche in the education of young physicians, but clinical methodology, ethics of biomedical research and clinical practice, and clinical critical thinking. Let us stay on this last subject.
What is critical thinking? It is the proper way Western and Eastern traditions have constructed their successes and reached their results over the centuries. It is the capacity to think correctly (and critically) about the problems, their solutions, and their justifications. In the medical case, this means the capacity to correctly analyze the pathological situation of the patient, to understand which kind of diagnosis and therapy to propose (this is the problem), to find the proper diagnosis and the proper therapy (the solution), and to justify the clinical decision which has been taken.
Needless to say, any oncologist should have the ability to think critically in the diagnostic and therapeutic phases since the patient’s life lies exactly in these moments. Nevertheless, no one is born with this innate ability, and it is important to have more than just a quick exposure to these topics to reach that ability at a professional level. This means teaching how to analyze an oncological problem and how to solve it. But this means also teaching the oncological students how to avoid the fallacies, that is, the wrong reasonings that they could do in their daily practice and that could be lethal for the patients they are curing.
In the last years, there has been an increase in the number of papers, written both by oncologists and by other physicians, dealing with the necessity of teaching clinical critical thinking (e.g. Nelson-Jones & Cosolo 2008; Papathanasiou et al. 2014; Boniolo et al. 2019; Boniolo & Campaner 2020; Jimenez et al. 2021; Scott et al. 2021; Kaur & Mahajan 2023; Martí-Bonmatí 2023; Ho et al. 2023). Moreover, many universities have implemented, in the curriculum of their medical courses, topics covering clinical critical thinking.[1] [For example, Araújo et al. 2024;
https://www.derby.ac.uk/research/showcase/critical-thinking-skills-healthcare-professionals/;
https://institute-academic-development.ed.ac.uk/study-hub/learning-resources/critical;
Two paradigmatic examples
To better understand what critical thinking competence means, let us consider two examples from the medical literature.
“The effect of the change in lower reference value for the "normal" sperm [...] depended on the probability distribution of the concentration in the population. [...] If it was heavily skewed, then most or all of the reported decline may have been a consequence of that change. The limited experimental data available indicates that the distribution was heavily skewed. [...] Depending on the actual distribution of sperm concentration in the population, the reported decline in concentration may have been accounted for entirely or partly by the change in lower reference value (Bromwich et al. 1994; my italics)
To critically analyze this passage, the first thing to do is to identify the statements it is composed of:
- D: “The effect of the change in lower reference value for the "normal" sperm [...] depended on the probability distribution of the concentration in the population”.
- P: “[The distribution of sperm concentration in the population] was heavily skewed”.
- C: “most or all of the reported decline [in sperm concentration] may have been a consequence of the change [in lower reference value for the "normal" sperm]”.
- P’: “The limited experimental data available indicates that the distribution was heavily skewed”.
- C’: “Depending on the actual distribution of sperm concentration in the population, the reported decline in [sperm] concentration may have been accounted for entirely or partly by the change in lower reference value [for the "normal" sperm]”.
The statement D is not relevant to the logical structure of the reasoning, but it serves to describe the context. P and C are part of the premises of the argument; P’ is the statement confirming P from the empirical point of view; C’ is the conclusion derived from P and C, given the confirmation of P.
It could be noted that in the passage above there are two extremely important words: “If … then …”. These link P and C, that is, we could write “If P then C”. But we know, with P’, that P is true, then it follows C’, that is, a restatement of C.
Summing up, we have
((if P then C) and P) then C.
This is a right way of reasoning the Medievals called modus ponens. It is the most pervasive correct inference rule we encounter in any field of our life where reason is to be applied. It allows, from two premises, one of which is a conditional (if P then C) and the other one is the antecedent of the conditional itself (P), to argue for a conclusion C, which is the consequent of that conditional. Modus ponens is at the basis of any diagnostic and therapeutic thinking: “If the patient would be affected by the neoplasia N, then he/she would have the symptoms S and the clinical exams of the kind E; but (from other clinical observations) we conjecture that he/she has the neoplasia N, then he/she has the symptoms S and the result E”.
Note that linked to this correct way of reasoning there is a fallacy, called the fallacy of affirming the consequent:
((if P then C) and C) then P
That is, it would be a fallacy to state that “If the patient would be affected by the neoplasia N, then he/she would have the symptoms S and the clinical exams of the kind E; but we know that he/she has the symptoms S and the result E, then he/she has the neoplasia N”. That is, while is correct to deductively infer from the pathology to symptoms and test results, it is wrong to try to deduce from the symptoms and test results the pathology. This is not a denial of the pivotal role of symptoms and test results in the determination of the right diagnosis, but a warning that there is no deductive inference between the former and the latter, but an inductive inference resulting in a hypothesis (the diagnosis is always a hypothesis).
Let us consider another example, “Thus, a single male line [...] has spread in the last 1,000 years to represent 8% of the males in a region stretching from northeast China to Uzbekistan. If this spread were due to a general population expansion, we would expect to find multiple lineages with the same characteristics of high frequency and presence in multiple populations, but we do not [...]” (Zerjal et al. 2003; my italics).
Again, we can observe that this passage is composed of the following statements:
- P: “the spread were due to a general population expansion”
- C: “we would expect to find multiple lineages with the same characteristics of high frequency and presence in multiple populations”.
- C’: “we do not [find multiple lineages with the same characteristics of high frequency and presence in multiple populations]”
- P’: “the spread were not due to a general population expansion”.
Another time, there are two words particularly relevant: one explicit (“if”) and one tacit (“then”), that is, “if … then …”. Thus, we have, “If P then C, but we know that C is not true from empirical observations (that is, C’), then P is not true (that is, P’= nonP).
((if P then C) and nonC) then nonP
Again, this way of reasoning is correct, and the Medievals called it modus tollens. Even the modus tollens is pervasive in the ordinary and scientific way of reasoning, in particular, it is used to eliminate a diagnostic or a therapeutic hypothesis that has been found to be false. “If the patient would be affected by the neoplasia N, then he/she would have the symptoms S and the clinical tests E; but we know that he/she does not have the symptoms S and the clinical results E, then he/she has not the neoplasia N”.
Also, the modus tollens has its correlated fallacy: the fallacy of denying the antecedent:
((if P then C) and nonP) then nonC
“If the patient would be affected by the neoplasia N, then he/she would have the symptoms S and the clinical tests E; but he/she has not the neoplasia N, then has not the symptoms S and the clinical results E”. Note that in the modus tollens case, symptoms and clinical results have a fundamental deductive role in proving the falsity of the clinical hypothesis. Differently, in the modus ponens case, they do not have any deductive role in establishing its validity. That is, while a negative clinical exam could falsify a diagnosis, a positive clinical exam does not prove at all the truthfulness of a diagnosis. By the way, truth does not exist in medicine!
All of this could be thought of as a mere subtlety, but it is a subtlety that can save lives. On the other hand, already the cases above show how a correct way of thinking allows for the proper understanding of the methodological role of the empirical observations.
Moral conclusion
To close and put it very simply: thinking correctly means saving patients’ lives, and an oncologist, on the one hand, should have the duty to think correctly and, on the other hand, should have the right to be trained to think correctly, that is, in clinical critical thinking.
References
Araújo B et al. 2024. Critical thinking pedagogical practices in medical education: a systematic review. Frontiers in Medicine II,
https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1358444.
Boniolo G et al. 2019. Why include the humanities in medical studies? Internal and Emergency Medicine 14, 1013–1017.
Boniolo G, Campaner R 2020. Life sciences for philosophers and philosophy for life scientists. What should we teach? Biol Theory. 15, 1-11.
Bromwich P et al. 1994. Decline in sperm counts: an artefact of changed
Casadevall A. 2015. Put the “Ph” Back in PhD. https://magazine.publichealth.jhu.edu/2015/rethinking-put-the-ph-back-in-phd
Ho YR et al. 2023. Thinking more wisely: using the Socratic method to develop critical thinking skills amongst healthcare students. BMC Med Educ 23, 173.
Jimenez JM et al. 2021. Development of critical thinking skills of undergraduate students throughout the 4 years of nursing degree at a public university in Spain: a descriptive study. BMJ Open. 11, e049950.
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Smith R. 2016. Medicine’s need for philosophy. April 8, https://blogs.bmj.com/bmj/2016/04/08/richard-smith-medicines-need-for-philosophy
Zerjal T et al. 2003. The Genetic Legacy of the Mongols. Am. J. Hum. Genet. 72, 717–721.