DE Weekly: Monism, Dualism, & Phenomenological Ontology
Below is an archived email originally sent on June 15, 2026.
Monism, Dualism, & Phenomenological Ontology
Like any philosophy, Existentialism boasts a wide array of philosophical thought, owing to the varying worldviews of its most prolific authors; Albert Camus is not the same as Jean-Paul Sartre is not the same as Martin Heidegger is not the same as Søren Kierkegaard. However, there are consistent through points that can be traced in the writings of all of the above.
That being said, we might ask ourselves: is there a common ontology that underpins the whole of existential thought (or at least much of it)?
Ontology refers to the study of being and existence as it constitutes our reality. Our ontology lays a foundation for our philosophy when we seek to answer questions such as, “Do I exist?” or, “What does it mean to exist?”
Sartre was one of those authors who advanced a cohesive ontological viewpoint for his own work, which he called phenomenological ontology. I would argue this is an appropriate way to describe his contemporaries, as well.
His phenomenological ontology provides a framework that helps us understand our being through examining our human experience and our consciousness.
In other words, as we seek to understand the universe ontologically, we would favor the way things (phenomena) appear to us and how we experience them (phenomenologically) instead of the method of studying the universe as an objective reality.
Such a mode of being is elucidated in Sartre’s Being and Nothingness, and of course in the works of his predecessors Heidegger and Edmund Husserl. So, if there is a criticism to be made about Existentialism, it cannot be that there is not a clear ontological framework––there certainly is.
But, a unique ontology does not arise from nowhere and in opposition to nothing. It seeks to distance and distinguish itself from another, usually preexisting ontology. In the case of Existentialism’s phenomenological ontology, what was that?
I believe we could say there were two: Monism and Dualism.
Monism is a philosophical worldview that reduces reality to a single, unifying substance or essence (e.g., God or the universe).
Monism is not only reserved for the spiritual, however. There are different types of monism, such as substance monism, that reduce the world to a physicalist makeup that holds only the physical material world exists.
There is also the monism of Baruch Spinoza which I wrote about earlier this year, which supposes God and His creation are not two separate things, but one and the same. His substance monism held that there is only one substance––God and nature––and that everything else is just a modification of that one substance (including us).
Then, there is the monism of Zeno, who I wrote about roughly a year ago, whose philosophy of monism posited that all existing things are singularly linked to one source, and that reality is singular, unchanging, and universal.
Dualism is a competing philosophical worldview that purports reality is composed of two fundamentally distinct principles or substances, not just the one.
The most famous example, as you might know, is the substance dualism popularized by René Descartes and his cogito, separating mind and body into two distinct parts, holding that the mind is a non-physical, thinking substance, while the body is a physical, spatially extended substance.
Just as with monism, there are many different strains of dualism concerning all sorts of realms, including religion, epistemology, and even psychology.
Between monism and dualism, which one (if any) had more influence on the phenomenological ontology of Sartre et al., and which one has more in common?
Both and neither, I would say. As I said at the top of this newsletter, Existentialism sought to distinguish itself from both monist thought and the Cartesian dualism that prevailed the preceding centuries of philosophy. But, it was certainly influenced by the existence of both in its own right.
The question we beg now is: did it accomplish this distinction? Let’s walk through it.
Where monism posits that all of reality is grounded in one unified substance such as God or the universe, Existentialism rebuts by separating the individual from the universe, emphasizing our total, radical freedom in life, wholly separated from any one substance.
Where dualism posits that that mind and body are fundamentally different and separate, existing independently of each other, Existentialism rejects any predefined notion of the sort, rebutting instead that we are inseparable from our consciousness and inseparable from the bodies our conscience inhabits.
We can better understand the distinction as we make our way back to Sartre’s ontology.
Sartre wrote that being-in-itself and being-for-itself each have unique characteristics. But, rather than being totally separated and exclusive of each other, the two are combined into one being: human beings, who embody both in some way.
And so, we are a bit ambiguous, as it were; we are both passive and inert, both acting and experiencing as a being-in-itself and as a being-for-itself.
Drawing on Sartre’s notions of facticity and transcendence, we all know that we are born with certain immutable characteristics that define us in some real way (either by limiting us or by helping us exceed), and we can transcend some of this inborn facticity through accepting our individual responsibility and exercising our radical freedom.
Sartre says that we are always “more” than our situation, and that this is the ontological foundation of our radical freedom.
Thus, this is how the unique phenomenological ontology of Existentialism distinguished itself from the limits of either monism or dualism.
“I must be without remorse or regrets as I am without excuse; for from the instant of my upsurge into being, I carry the weight of the world by myself alone without help, engaged in a world for which I bear the whole responsibility without being able, whatever I do, to tear myself away from this responsibility for an instant.” ― Jean Paul Sartre, Being and Nothingness
Thanks for reading.
Sincerely,
Brandon J. Seltenrich
P.S.––
The past few newsletters have drawn from other philosophies to illustrate some lessons, so I figured we were due for a return to the weeds of Existentialism for some fun. Hope you got something out of this one.
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