Humors, Passions, and Consciousness in Descartes’s Physiology: The Reconsideration through the Correspondence with Elisabeth

From Firenze University Press Book: Reading Descartes

University of Florence
5 min readFeb 19, 2024

Jil Muller, Paderborn University

In René Descartes’s oeuvre, his readers and critics play a major role, as they push the philosopher to reconsider some of his quintessential philosophical and scientific terms in his work in progress. This critical engagement with Descartes enables one to identify essential changes in his philosophical positions, one of which concerns Descartes’s understanding of the concept of the passions, which he modifies after exchanging letters with Princess Elisabeth of Bohemia about her sadness and melancholy. In this case, we can see an important shift from the concept of humor, which is used by Descartes in the Treatise of Man (finished c. 1633), to that of passion, present in his Treatise of the Passions (1649). The term “humor” (French: humeur) as Descartes understands it goes back to the Galenic theory of fluids in the body, which trigger various moods, character traits and even diseases. In light of recent scholarship, we now know that Descartes read Galen and took a course on him at the University of Leyden (Bitbol-Hespériès 1990, 31–52; Starobinski 2012, 21–34 and 42–6; Lebrun 1995, 18–25; Teyssou 2002). Galen greatly influenced the medicine of his time by continuing the Hippocratic theory of body-fluids. The theory of the four humors was taken up again by many philosophers in the Renaissance (especially in the 16th century) to describe the human body and above all to understand melancholy. The word “humors” historically in ancient and medieval western medicine has two meanings: first, in Hippocrates’s and Galen’s theory, the humors are “the nourishment of the body, i.e. of its tissues, which consequently owe their existence to the humors” (Temkin 1973, 17) that is, they refer to the four main vital bodily fluids (blood, yellow bile, phlegm and black bile: Hippocrates 1823; Hippocrates 1983). It is especially Galen who retains humorism1 as a medical theory and proposes taking account of imbalances in any of the four humors as a means of diagnosing patients with a variety of diseases (Galen 1916, book 2, chapter 8, 169–95, and chapter 9, 209–19). This imbalance is the direct cause of certain diseases and is usually inflected by variations in weather, geography, age and even by certain occupations or works (Galen 1981; Galen 2007–2019, and especially, Galen 1995). Secondly, Galen describes humors as being related to temperament, usually accepted as psychological dispositions, which Galen, however, uses to refer to bodily dispositions. These bodily dispositions give information about mood, behavioral and emotional inclinations and about predispositions for certain diseases. Therefore, it seems logical that Descartes at first refers to Galen, when he discusses melancholy with Elisabeth. In the Treatise of Man, Descartes adopts the term “humor” and agrees with Galen’s explanation. However, his understanding of the humors and passions changes during the correspondence with Elisabeth, from 1645 onwards, even if he had already discussed passions and animal spirits in his correspondence with Henricus Regius in the early 1640s. The correspondence with Regius mainly concentrates on the metaphysical understanding of passion as a thought and on the interaction between an agent (the body) and a patient (the soul). In the correspondence with Elisabeth, however, Descartes seems to be pushed to consider body and soul united, equally involved in the process of causing and reacting to the passions, as Elisabeth pushes him in this direction through her own arguments on sadness.

While in the Treatise of Man Descartes used the concept of inner feelings (caused by external objects or by internal dispositions of the body), humors and passions, he only clearly differentiates between humors and passions, and between inner feelings and passions, in his correspondence with Elisabeth and in his subsequent works. The passions are all thoughts that are evoked in the soul without her will being involved (AT 4, 310; CSMK, 270), while the inner feelings, on the contrary, are caused by external objects or by internal dispositions of the body. This then raises the question of what caused Descartes to examine all of these terms more carefully. What role did consciousness play in the humors and the passions? And why does he remove some of these concepts from his theory of the passions? At the beginning of the correspondence with Elisabeth, Descartes has a slightly different interpretation of the concepts of passions and humors. But by discussing the sadness and melancholy which burden Elisabeth in everyday life, Descartes understands that he needs to explain the functioning of the passions more precisely. The interaction between body and soul plays a decisive role in arousing, triggering and controlling the passions. Therefore, Descartes must examine the elements that trigger the soul or body to discover what causes the passions. As is well known, Descartes uses the term “passion” in three different contexts: in physics, in physiology and in psychophysics.

In physics, a passion is anything that ‘takes place or occurs’ as the result of ‘that which makes it happen’ (AT XI 328, CSM I 328). In physiology, a passion is a corporeal impulse of the animal body (AT V 278, CSMK 366). In psychophysics, ‘passions of the soul’ are modes of the soul that ‘depend absolutely’ on actions of the body (AT XI 359, CSM I 343) (Brown 2016, 563–69).

This chapter will especially focus on the two last dimensions in physiology and psychophysics, by identifying the role that comes to consciousness in the passions. This chapter will show that the discussion with Elisabeth about her sadness or melancholy launches a different understanding of the passions and constitutes the turning point for Descartes’s change in the understanding of the concept of the humors. There are several studies of Elisabeth’s melancholy and the correspondence with Descartes. In this context, Elisabeth’s precise analysis of the interaction between body and soul in the union is often brought up, and Descartes scholars have shown that she calls on Descartes to explain the union and passions more clearly. However, no one has dedicated a complete study to Descartes’s modification of the concepts of the humors and passions all through his own works, from the Treatise of Man to the Treatise of the Passions. Therefore, it is important to take a close look at this change and to show the role played by Elisabeth’s letters, especially those written in 1645. In this context, I will start by explaining Descartes’s interpretation of the humors in his early work, and the passions in his later work, in order to clarify the shift between these two concepts. Thereafter, I will analyse Elisabeth’s letters about sadness and melancholy and Descartes’s responses to find the pivotal element in Descartes’s change of understanding. Elisabeth, by describing her own sad feelings and thoughts, helps to change Descartes’s view of the passions so that the concept of humors is no longer appropriate.

DOI: 10.36253/979–12–215–0169–8.05

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