Book Review | William Spears’ Stoicism as a Warrior Philosophy: Insights on the Morality of Military Service

Stoicism as a Warrior Philosophy: Insights on the Morality of Military Service. William Spears. Casemate, 2025, ISBN 978-1636246239, pp. 288. $19.95.

Typical works on Stoic philosophy focus their attention on Stoic ethics. This might be argued to be the enduring wisdom of the ancient philosophy that still holds value in our contemporary era. However, William Spears examines ancient Stoicism in its entirety, including discussions on Stoic logic and physics.

As explained by Spears, Stoic logic serves as the foundation of their philosophy. It places emphasis on the importance of reason and rational thinking. Stoic philosophy held that discerning and reasoned thought enables a more profound understanding of the world, thereby facilitating sound decision-making. The Stoics formulated an intricate system of logic encompassing theories of perception, language, and knowledge. This rational method was vital for discerning between valid and invalid beliefs, essential for attaining wisdom.

Within philosophy, physics denotes the examination of the natural world and the universe. The Stoic perspective held that the universe exists as a rational and interconnected whole, subject to divine reason, or logos. They posited that all events occur in accordance with natural laws, and comprehension of these laws facilitates personal alignment with the natural order. This viewpoint cultivates acceptance and serenity, acknowledging events are uncontrollable and should be met with composure.

Ethics constitutes the applied dimension of Stoic philosophy. It emphasizes the importance of virtuous living, guided by reason and nature. Stoic philosophers recognized four principal virtues: wisdom, courage, justice, and temperance. Through the cultivation of virtue, individuals may attain eudaimonia (happiness), leading to a flourishing existence. Stoic ethics posit that genuine happiness originates internally and remains independent of external factors. This internal strength allows people to safeguard their moral compass and inner harmony, no matter the trials of life.

While Spears’ comprehensive examination of ancient Stoicism provides significant strength to this book as an academic work, it may be a weakness in exploring Stoic ideas through time. Spears wrote a book specific to ancient Stoicism, a philosophical school locked within a specific timeframe. This unfortunately hampers some of his discussions later in his work trying to relate Stoicism to the needs of modern warriors. While he relates ancient Stoicism to the warrior’s responsibilities to follow the laws of war, Spears misses the opportunity to discuss how the laws of war grew out of the NeoStoic tradition. NeoStoicism was a philosophical movement, started in the late 16^th century by Justus Lipsius, who reconciled ancient Stoic ethics with Christian theology. The NeoStoic Hugo Grotius, “the father of international law,” wrote the “first general comprehensive modern work grounded on reason and natural law” with his De jure belli ac pacis (On the Law of War and Peace). Spears should not be faulted here because there is only so much one can put into a single book. The quality of Spears’ research on ancient Stoicism is more than sufficient to make his work a valuable resource for anyone interested in military Stoicism.

While Spears advocates the self-study of Stoic philosophy, he does not promote the military teaching this philosophy as a standardized course. In my private conversations with Stoic educators, there has been a genuine fear expressed that instructors who are not invested in this philosophy would do a poor job of explaining it to new recruits. This could cause service members to reject the philosophy out of the failures to motivate learners common with military instruction. Spears also is hesitant to deal with the theological references in ancient Stoic physics. Modern Stoicism (a philosophical school developed in the last 60 years) does not take as full of a look at the philosophy as Spears, as previously discussed. Modern Stoic materials typically address Stoic ethics which could resolve some of these issues. There are surely forms of modern Stoicism that can support the range of religious beliefs from atheism to polytheism. The Stoic-based Before Operational Stress (BOS) program developed by Dr. Megan McElheran of Wayfound Mental Health Group might be a powerful example for the military in how Stoic instruction might be best integrated into a psychological resiliency program.

If placed on the continuum of Stoic materials for a new student of this philosophy, Spears’ Stoicism as a Warrior Philosophy it would certainly be towards the middle, between popular light reads and heavy academic investigations. While this could be used as an introduction to Stoicism, the depth of this work would probably be better suited to someone that had already read a contemporary intro to Stoicism like Donald Robertson’s How to Think Like a Roman Emperor and at least a few of the primary sources, like Marcus Aurelius’ Meditations, Epictetus’ Enchiridion, and Seneca’s Letters from a Stoic. Nonetheless, Spears’ work is worth to reading before exploring the effects of Stoicism on the creation of the American Republic, as is found in works such as Goodman and Perkins’ Rome’s Last Citizen. For further information on the influence of Stoic philosophy on early American military education, Controversial History & Educational Theories of Captain Alden Partridge (Marching with Spartans: The Life and Works of Alden Partridge VOL I) provides further materials on the evolution of Stoic thought that wasn’t included in Spears’ work.

To conclude, William Spears’ Stoicism as a Warrior Philosophy constitutes a valuable resource for any service member or scholar seeking a deeper understanding of ancient Stoic philosophy. This text is infinitely superior to Nancy Sherman’s Stoic Warriors, in discussing ancient Stoicism and the modern service member. It is obvious Spears invested significant time and attention to detail in his research, attempting to reconcile contemporary military service and this incredibly powerful philosophy. The hope is that Spears’ example will inspire other service members to dare to be military philosophers to further advance the profession of arms.

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