Naturalism is a powerful idea in both philosophy and science. It’s the belief that everything comes from natural processes and follows the fixed laws of nature, like gravity or chemistry. This view completely leaves out the idea of the supernatural (things like magic, spirits, or unexplained forces). Instead, naturalism says that we can use science to investigate and explain all parts of reality, including human life and the entire animal world. Here we will explain the main ideas behind naturalism, show how it’s used to study animals, and introduce you to a few famous scientists who helped build this way of thinking.

What Naturalism Means in Philosophy

At its heart, philosophical naturalism is the straightforward belief that nature is all there is. This means the universe is made only of physical things: matter, energy, and the rules that govern them, like space and time. Because of this, anything non-physical or supernatural (such as deities or disembodied souls) is seen as nonexistent or at least irrelevant to how the physical world works. This view insists that reality is solid and consistent, and the best way to gain true knowledge is through the scientific method: careful observation, testing, and gathering evidence.

Naturalism as a Scientific Rule

The philosophy of naturalism is the reason science operates the way it does. Scientists follow what is called methodological naturalism. This is a working rule that says to explain anything in the lab or the field, you must use only natural causes. For example, a geologist explaining an earthquake must use plate tectonics, not a mythological giant. This rule is necessary because if scientists allowed unpredictable, non-natural forces into their explanations, they couldn’t test their theories or find real solutions. The incredible success of modern science is proof that this naturalistic approach works.

Applying Naturalism to Animals

When we look at animals, naturalism becomes essential. It dictates that all animals are entirely the result of material forces, specifically the biological processes of genetics, changes in DNA, and, most importantly, natural selection. This scientific outlook was a major shift from earlier times when some people thought animals were merely simple, unthinking machines. Under naturalism, we see an animal as a complex organism whose body, functions, and behavior are perfectly shaped and connected to its environment through the constant pressure of survival.

Natural Selection: The Key Mechanism

The most important idea that connects naturalism to the animal kingdom is Charles Darwin’s theory of evolution by natural selection. This theory is the ultimate natural explanation for how life became so diverse. It shows that life developed without any higher plan or external purpose. The mechanism is simple: animals with traits that help them survive and reproduce are the ones that pass on their genes. A bird has a certain beak shape because its ancestors with that shape were better at finding food. All the amazing complexity of the animal world is explained by natural forces working over vast amounts of time.

Ethology: The Science of Animal Behavior

The specific science of studying animal behavior in its natural setting is called ethology. Ethologists start with the naturalistic assumption that everything an animal does, whether it’s a learned trick or a deep instinct, is controlled by physical factors like genetics, brain chemistry, or cues from the environment. Ethologists study the why behind behavior by asking 4 main questions: what causes the behavior, how does it develop in the individual, why did it evolve, and what is its use for survival? They strictly avoid anthropomorphism, which is giving animals human emotions or motivations.

Charles Darwin: The Most Famous Naturalist

Charles Darwin (1809 – 1882) is undoubtedly the most influential figure in making the naturalistic view dominant in biology. Based on years of observation, his book On the Origin of Species (1859) gave scientists the 1 thing they needed: a way for life to arise and change without needing the supernatural. Darwin showed that everything about life on Earth, from tiny insects to humans, could be explained by a few simple, constant rules found in nature. He is rightfully considered the single most important architect of modern life science.

Carl Linnaeus: Organizing the Natural World

Carl Linnaeus (1707 – 1778), who lived before Darwin, was essential because he created the system for organizing the natural world. He is known as the father of modern taxonomy. Linnaeus invented the 2-name naming system (like Panthera leo for a lion) that we still use globally to classify all living things. By carefully grouping plants and animals based on their shared physical features, he created the organized structure that later helped scientists like Darwin see the clear connections and relationships between all species.

Alexander von Humboldt: A Global Perspective

Alexander von Humboldt (1769 – 1859) was a German explorer and scientist who helped create the science of ecology. Unlike earlier naturalists who just collected specimens, Humboldt looked at the whole picture. He saw nature as 1 giant, interconnected web. He measured and mapped how physical factors like elevation, temperature, and geography affected where different plants and animals were found. He proved that the distribution of life is not random but can be fully explained by measurable natural factors, connecting biology to geology and meteorology.

Jane Goodall: Observing the Wild Closely

A great example of a modern naturalist was Dame Jane Goodall (1934 – 2025). She was famous for her study of wild chimpanzees in Tanzania that lasted decades. Goodall’s work was purely based on long, patient, non-interfering observation. She discovered that chimpanzees make and use tools, have complex social structures, and even engage in conflict, behaviors that were previously thought to be unique to humans. Her detailed naturalistic findings confirmed that we are all part of a continuous spectrum of natural life, just as evolutionary theory predicts.

The Overall Impact of Naturalism

The biggest takeaway from naturalism is that it provides a single, consistent way to understand all living creatures. Every animal, from the smallest bug to the largest whale, is an important part of a huge, amazing system that follows understandable, natural laws. This shared way of thinking, practiced by naturalists throughout history, gives us the essential tools and viewpoint needed to properly study, protect, and understand the incredible variety of animal life on our planet.