Natural theology is the study of God and divine truth using human reason and observation of the natural world, without depending on religious texts or revelations. Different philosophers have approached natural theology in various ways, depending on how they see the world and the human mind. Plato, one of the earliest philosophers to deal with these ideas, believed that reality is divided into two parts. First, there is the world we know through our senses—changing, imperfect, and temporary. Second, there is the eternal and changeless world of perfect Forms, which we cannot fully see or experience with our senses. For Plato, nature is not just physical matter—it is a way to understand something deeper. The beauty and order in nature are like signs pointing to a higher, perfect reality. This means that nature itself reveals something about the divine, even if we can’t fully understand it.
Aristotle, Plato’s student, had a different view. He believed that instead of looking for truth in a world beyond, we should use logic and reason to understand what we experience directly. For Aristotle, natural theology didn’t mean looking at something far from human understanding, but using our minds to understand what is already around us. He believed in a “pure being” or “unmoved mover”—a divine force that causes everything but is not caused by anything. Aristotle’s approach is more scientific and practical, focusing on what we can observe, think about, and explain through reason.
Thomas Aquinas, a Christian philosopher and theologian, tried to bring together faith and reason. He was influenced by both Plato and Aristotle but went even further. Aquinas believed that we can know things about God through reason, but we must be very careful. We cannot talk about God in exactly the same way we talk about humans or objects, because God is beyond full human understanding. But we also cannot say that we know nothing about God. Aquinas said we need to avoid being too literal (pure univocation) and too vague (pure equivocation). Instead, we use analogies to talk about God—comparing Him to what we know, while remembering that God is still greater. He also believed in “pure contingency,” which means that everything in the world depends on God to exist, while God depends on nothing. For Aquinas, true knowledge comes when we accept that balance between reason and faith.
In the pre-Kantian modern philosophy period, thinkers started moving away from metaphysics and the idea of knowing God as something beyond. Many became skeptical of trying to use reason to explain divine truths. Instead, they focused more on human experiences. Some pre-Kantian apologists still defended natural theology, but they began to stress the importance of the experiencing subject—the human person. They argued that our minds are active in shaping what we know. Kant later criticized rationalism by saying that human reason has limits. His argument was similar to Aristotle’s, saying that not everything can be explained by reason alone. Kant believed that we only know things as they appear to us, not as they truly are.
Finally, in post-Kantian phenomenalism, natural theology became even more focused on individual experience. Phenomenalism says that we don’t know things as they are in themselves, only how they appear in our minds. This led to a view of theology that was less about objective truth and more about personal meaning and how we experience the world. From Plato to post-Kantian thinkers, natural theology has moved from believing in eternal truths beyond the world to focusing on the human mind and how we experience reality.