Why We Think What We Think: The Rise and Fall of Western Thought
By Dan LeRoy.
Sophia Institute Press, 2024.
Paperback, 240 pages, $19.95.

Reviewed by David Weinberger. 

“How did we get from a world in which some of the smartest people in recorded history were philosophers—a world in which philosophy gave birth to science and made sense of religion—to a world in which philosophy has become, at best, the setup for a punchline?”

This is the question posed by author and journalist Dan LeRoy, whose new book, Why We Think What We Think: The Rise and Fall of Western Thought, examines the history of western philosophy to help us answer that question and to understand the way we think today.

This story, as LeRoy chronicles, begins in ancient Greece. There, several centuries before Christ, thinkers began using reason to understand the world around them. What, they wondered, is the nature of reality? Thales, considered the first official philosopher in history, suggested that everything is made of water. If this sounds silly, consider both that the human body is mostly water and that all living things depend on water for their survival. Furthermore, because water changes from liquid to solid to gas, it seems to account for the manifold changes that occur in the natural world. Lastly, because land itself is surrounded by water, it appears to be the fundamental “stuff” on which the world floats. So, Thales thought, it must be basic to reality.

Of course, it is not for this argument that Thales remains important for us today, but for his demonstrating the value of reason and critical thinking. As LeRoy writes, “beginning with Thales, Western philosophers encouraged their students ‘to discuss, debate, criticize—and to produce a better argument or theory if [they] could.’” 

And subsequent philosophers did indeed try to produce better theories. Pythagoras, for instance, thought that the orderly divisions and ratios within the cosmos revealed that numbers were the basic building blocks of reality. Others, meanwhile, proposed air, fire, or other things as fundamental. But whether water, numbers, air, or fire, each of these alternatives held that reality was composed of one kind of thing. In philosophy, this is known as “monism.” 

A more sophisticated understanding developed just a few years later. Plato, following the work of his teacher, Socrates, argued that reality is not composed of one type of thing, whether water, numbers or anything else, but instead constitutes a hierarchy of “Being.” 

To understand Plato’s insight, consider that when I look at a pine tree and a maple tree in my backyard, I recognize that they are both trees. But how is this possible? After all, they differ in size and shape, so based simply on my sense experience—that is, based solely on how they appear to me—they are different. So, how is it possible for me to know that they are both the same kind of thing (trees) and not two different kinds of things (say, a mountain and a fish)? For Plato, this is possible because they both “participate in” the Form of being a tree. In other words, through my experience encountering trees in the world, my mind comes to grasp (“recollect,” according to Plato) the universal intelligible structure or “Form” of what a tree is. I then use this Form to identify the individual trees I experience as trees and not as, say, mountains or fish. Thus, for Plato, the Forms exist in a higher and more perfect dimension than the world of our experience, which gets its intelligibility only insofar as it “participates in” this realm of Forms.

Very well then, but where do the Forms get their intelligibility? Plato held that at the summit of reality—above even the Forms—stands the Good, which is the eternal and unbounded unity of perfection, goodness, and truth. As such, it transcends the Forms and is their source of reality and meaning. To borrow an analogy from Plato himself, just as the sun illuminates objects in the world, so the Good illuminates the Forms.

So much, then, for Plato’s theory. His student, Aristotle, agreed with much of this picture, including the idea that Forms constitute objective and eternal truths. Aristotle, however, insisted that the Forms are not separate from but built into the world we inhabit. Furthermore, he developed a doctrine known as “the four causes” to improve critical inquiry. To see how it works, let’s apply it to the Statue of David. According to Aristotle, there are four distinct modes of understanding it, and we must know all four of them if we want a complete explanation of it. First is what the statue is made of, or its “material cause.” In this case, the marble. Second is who or what made the statue, or its “efficient cause.” The efficient cause here is the sculptor, Michaelangelo. Third is what the statue depicts—i.e., its intelligible structure or form. This is its “formal cause”—which, in this case, is David. Last is the statue’s aim or purpose, or its “final cause.”  The final cause of the statue is, quite simply, to express beauty. Together these “four causes” reveal unique aspects of the statue, and lacking any one of them would render our understanding incomplete. 

Now, while much more could be said here, the point is that the philosophical framework Plato and Aristotle developed endured for more than 1,500 years—though of course there were important contributions along the way. LeRoy, in fact, does an excellent job covering them in his book. To cite one example, Augustine deepened Plato’s and Aristotle’s understanding of the Forms. Recall that, for Plato, the Forms exist insofar as they participate in “the Good.” Aristotle, meanwhile, argued that the Forms are embedded in the very structure of the material world itself. What Augustine realized, however, is that since the Forms constitute eternal and immutable truths, their source must be an eternal and immutable mind. In other words, Forms pervade our world because a divine intellect eternally “thinks” them into being. As LeRoy observes, “This idea of the Divine Mind as the source of things like universals and numbers [i.e., Forms] was probably Augustine’s neatest synthesis of his own thoughts and Plato’s.”

However, beginning in the 1300s, cracks in the foundation began to appear. The crucial philosopher in this regard is William of Ockham. Today, he is known for his famous principle, “Ockham’s Razor,” which maintains that the simplest answer is usually the right answer, since a more complicated answer is more likely to contain errors. More significant, though, is an idea of his that has had lasting corrosive consequences for philosophy: nominalism. Nominalism holds that Forms do not constitute objective realities but merely reflect the way we think and talk about things. For example, we saw that for Plato and Aristotle, Forms are universal truths or intelligible patterns that our minds discover in reality. So, for instance, when we perceive an object in the world as a “tree,” we do so because we grasp a certain universal Form, i.e., the Form of being a tree. For nominalists, however, when we perceive an object in the world as a “tree,” we are not grasping a universal Form, i.e., the Form of being a tree; we are merely constructing a concept in our minds. 

Now, if this is true, if universal Forms refer only to concepts in our minds and not to objective features of reality, then, as LeRoy explains, we simply “have to trust that we’re all talking about the same thing when we call an apple ‘red.’ But we have no real way of knowing that this is so—because how can we really know what’s happening in someone else’s mind?” For another thing, if there are no universal Forms outside the mind, then there are no universal “natures” or “essences” to things in the world. In other words, there is no such thing as “human nature.” And if there is no human nature, then there is no human purpose. In Aristotelian terms, if we cannot say what a thing is (its “formal” cause), then we cannot say what its purpose is either (its “final” cause). This, however, brings us to the most fundamental problem with nominalism. If universal Forms are merely concepts in our mind that do not lay hold of anything in reality, then “nominalism” itself is merely a concept in our mind that does not lay hold of anything in reality. Therefore, it is meaningless.

For these reasons (among others), nominalism is a notoriously difficult view to defend. Still, it is worth considering why Ockham adopted it. Ockham did so not because he wanted to deny the possibility of conceptual knowledge about the world, for he firmly believed—in direct contradiction to the nominalism he espoused—that we can indeed possess such knowledge. Rather, he did so because he wanted to protect God’s omnipotence (i.e., His being all-powerful). According to his thinking, the idea that contingent creatures might understand the omnipotent Creator takes human reason beyond where it can rightfully go. In this way, nominalism served as a “reminder of God’s supreme power and our inability to understand that power in the world around us,” notes LeRoy. In short, then, Ockham attacked reason to make room for faith. Once faith declined a few centuries later, however, nominalism ended up paving the way for skepticism. 

By early modernity, for example, because notions of “formal” and “final” causality had largely dropped out of the picture, thinkers struggled to explain how we could get outside of our minds to know external reality at all. Seventeenth-century philosopher René Descartes, for example, tried using doubt to ground such knowledge, which ultimately led him to conclude that the mental is radically distinct from the physical, and that we are fundamentally “minds” trapped in bodies. Ergo, a new gulf opened between mind and body that persists to this day and that has served only to raise additional questions about how we can access the external world. Descartes’ younger contemporary, John Locke, fared little better. Locke maintained that because we cannot know the underlying “essences” or “natures” of things, we cannot even know ourselves. “We are substances I know not what,” he woefully remarked. Following him, philosopher David Hume went further by suggesting that we cannot even know that we are “substances.” For Hume, the most we can say is that we are mere bundles of sense impressions. 

By the twentieth century, philosophy was so disabused of the idea that it could tell us anything even remotely meaningful that it reduced itself to analyzing language. As LeRoy writes, “We couldn’t know God. We couldn’t know the material world. We couldn’t even, according to the skeptics, know ourselves. It’s not surprising, then, that language became the thing philosophers grabbed onto like a life preserver.”

Of course, given the long history we have seen of either denying or ignoring the “formal” and “final” causal aspects of reality, it seems inevitable that philosophy would turn into an arcane, dull, and hyper-specialized discipline today. Without formal and final causes, after all, we have no access to the universal intelligible structures and purposes in the world. And without those, there is no possibility of meaningful philosophy.

Properly understanding this, though, requires understanding the thinkers and the thoughts that have enabled it. For that, Why We Think What We Think is a great place to begin.


David Weinberger formerly worked at a public policy institution. He can be found on X @DWeinberger03.


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