THE THOMIST - CURRENT ISSUE

* Previous issues of The Thomist can be accessed electronically through Project Muse.

Volume 90, Number 4, October 2026

Articles

Light in the Causal Order According to St. Thomas

Christopher A. Decaen

Abstract: Although a great deal of attention has been given to Aquinas’s understanding of the light of the intellect, little is made of his understanding of physical light, and even less of how he conceives of light’s role in the order of the physical cosmos. One suspects that the reason for this scholarly reticence is an underlying suspicion that Aquinas has nothing of relevance to say when science has come so far since the thirteenth century. This essay aims both to make a start toward filling the lacuna and toward showing the ways in which Aquinas’s views about physical light—both its nature and its causal role in nature—are worth taking seriously. I confirm the latter point indirectly by explaining out how contemporary science’s view of light as an electromagnetic wave bears a certain resemblance to Aristotle and Aquinas’s definition of light as the “act of the transparent” and the way this act functions as a quasi-universal instrumental cause.

Keywords: light, transparent, color, electromagnetism, Aquinas, sun, causality

pp. 583-626

Essences and Anglerfish: Does Polymorphism Refute Thomistic Biological Essentialism?

William Hannegan

Abstract: Thomistic biological essentialism is faced with the problem of intraspecific variation. David Oderberg and Edward Feser offer a solution to this problem. I argue that Oderberg and Feser’s proposed solution is insufficient because it cannot handle cases of polymorphic and polyphenic variation. Thomists, however, are not forced to abandon biological essentialism altogether. I offer a version of Thomistic biological essentialism, inspired by Charles De Koninck and Mortimer Adler, which can better accommodate polymorphic and polyphonic variation.

Keywords: essence, nature, property, intraspecific variation, species, biological essentialism

pp. 627-666

Mode as Differentiating Principle of Virtue: The Example of Humility and Magnanimity

Juraj Nevjestic

Abstract: Thomas Aquinas distinguishes the cardinal virtues not only by their subjects—the powers of the soul that each virtue perfects—but also by the modi of moral virtue. The modi are more operative as a principle of division in the Secunda secundae. I show both that the modes are quasi-formal principles of moral virtue as such, and yet that the moral virtues are distinguished according to the predominance of one of these four modes over the others. I focus on the modes of curbing (refrenatio or moderatio) and strengthening (firmitas) particularly, arguing that the former consists in a rational measure in the sense appetite whereas the latter consists in the very stability or steadfastness of the sense appetite already measured by curbing. I end by considering Aquinas’s division of humility and magnanimity in light of his account of the modes, arguing that humility exhibits the predominant mode of curbing in restraining the passion of hope, whereas magnanimity exhibits the predominant mode of strengthening in rendering the sense appetite steadfast against despair.

Keywords: Thomas Aquinas, moral virtue, cardinal virtue, mode, humility, magnanimity

pp. 667-690

An Ecclesial Theology for a Postliberal Age

James Massa

pp. 691-698

Reviews

The Humanity of Christ as Instrument of Salvation: A Study in Thomistic Christology, by J. David Moser (review)

Aaron Canty

pp. 699-702

Body and Identity: A History of the Empty Self, by Angela Franks (review)

Mark K. Spencer

pp. 702-706