Naturalism and Reductionism

In this essay we shall approach the phenomena of consciousness from two broad perspectives: the scientist and the philosopher. That is not to say that all scientists consider consciousness one way, and all philosophers another, or that there cannot be many who are both scientists and philosophers. Rather, we shall uncover some curious quirks regarding the phenomena of consciousness which are revealed by considering the broadly scientific approach to uncovering its nature, the scientific limitations of such an approach, and the potential for moving beyond such limitations. Throughout the discussion we will fall back on insights from philosophy to navigate the challenges faced by a science of consciousness. This is the first part of this essay.

Natural Science

Over 2,500 years ago, in the pre-Socratic era in the 5th and 6th centuries BCE, humans were seeking explanations for phenomena, and ultimately existence itself, that did not rely upon the supernatural (e.g. religion and gods). Figures like Thales, Anaximander, and Heraclitus sought to understand the world through observation, reasoning, and plainly thinking rather than systematic experimentation. While they occasionally engaged in basic experiments (such as Thales' measurements of the pyramids' heights using shadows) their methods were predominantly non-experimental. So, we describe these individuals as natural philosophers in reference to their seeking of natural explanations for all phenomena but without the rigorous experimentation and methodology that would make them proper scientists. Over many centuries, the gradual introduction of specific methodology and a critical emphasis on reproducible experimentation, demonstrated by figures like Galileo Galilei in the 17th century, evolved natural philosophy into modern science.

With the gradual emergence of science out of natural philosophy came a convention towards materialism. If naturalism is the belief that purely natural explanations exist for all phenomena, then materialism takes this one step further by suggesting that purely material explanations exist for all phenomena. Put differently, materialism in its greatest form is the philosophical belief that everything that exists is made out of matter, and by understanding completely how matter interacts, evolves, and arises we can understand existence in its entirety. A tempting view, but ultimately one rejected by modern science. In the late 19th century, scientists encountered phenomena that were fundamental to the universe but which were not suitable for explanation through purely material means. These included the discovery of new forms of energy and fields, with the work of James Clerk Maxwell on electromagnetism being a key example. With the discoveries of quantum mechanics and Einstein’s theory of relativity in the early 20th century, materialism was no longer sustainable. Today, materialism has been replaced with physicalism. Physicalism is the philosophical belief that everything that exists is made out of physical entities (fields, particles, or even strings), and by understanding completely how these physical entities interact, evolve, and arise, we can understand existence in its entirety.

Let us speak more clearly about what role physicalism plays in modern science. Specifically, I suggest that physicalism plays the role of an axiom for all the modern natural sciences. What exactly constitutes a belief in science as an axiom rather than a theory or a scientific fact? In science, we regard observations as facts insofar as we can confirm the observations as legitimate. Therefore, it is a scientific fact that the sun rises and sets in a 24 hour cycle. Scientific theories are explanations which elucidate the mechanisms underpinning a wide array of observations specific to the relevant scientific discipline. Importantly, a valid theory must be falsifiable. Put differently, for a theory to be scientific it ought to explain our observations (or facts) in a manner that produces additional predictions which are suitable for experimentation to either reinforce or invalidate the theory. However, there is a class of beliefs which are neither theories nor facts but which are critical in enabling scientific progress: the philosophical axioms. The axioms are beliefs which are taken to be true, but which are not based on direct observation nor are they falsifiable, and thus they cannot be facts or theories.

Let us look at an example of a theory: that of evolution in the field of biology. Evolution, by our definitions, cannot be a scientific fact since it is not itself an observation. Rather, it is a natural explanation for many observations. In addition, the theory of evolution is generally considered falsifiable since it makes specific predictions (e.g. in the fossil record) which can be tested. Clearly it is key to science that a theory can be proven false, but importantly our theories cannot ever be proven true. Instead, scientists gain a certain level of confidence in a theory based on its performance, and this confidence allows us to progress. This is the way of science, to say “if we assume so-and-so, then we theorize such-and-such”. In our example of evolution entire subdisciplines have emerged which necessarily assume that biological evolution is true, those being evolutionary psychology and biology. However, if we go back far enough in the assumptions upon assumptions we will eventually encounter the philosophical axioms of the field. All of the subsequent theories of the natural sciences build off of the starting block: “if we assume physicalism…” But is physicalism not a theory in its own right? It is not, particularly due to the requirement of falsifiability, as there is no possible experiment which we can conceive of today that would distinguish physicalism from idealism (the belief that reality is fundamentally mental or immaterial) or non-dualism (the belief that distinctions between the physical and the mental are illusory). This realization is of immense importance, so we shall state it again succinctly: over many centuries of development modern science finds itself built upon the assumption of physicalism, but this assumption is not itself subjectable to scientific experimentation, verification, or even falsification.

Reductionism in Science

At this moment you are reading this essay on some amazing piece of technology. In fact, we are surrounded by medical breakthroughs, modern conveniences, and constant signs of progress. If physicalism wasn’t correct then how can we explain its tremendous results? An exploration of reductionism helps to clarify such questions. Reductionism is a principle of science which states that the natural disciplines build off each other in such a way that certain fields are really just abstractions of more fundamental fields. If we had a complete ability to implement the more fundamental field then we wouldn’t need the abstract field at all. A key sequence in scientific reductionism would be the reduction of all animal behavior to biology, the reduction of all biology to chemistry, and the reduction of all chemistry to physics. In fact, modern scientific reductionism posits that all phenomena no matter how large and abstract (like sociology or economics) ultimately can be reduced to the principles of physics. In practice, we usually cannot get any meaningful fraction of the information needed to explain even simple phenomena purely using fundamental physics. Rather, reductionism plays an important philosophical role in the structure of science. Reductionism is not an axiom, or a theory that can be tested, but a reference to the “if we assume so-and-so, then we theorize such-and-such” structure of science. If someone were to ask a biologist increasingly specific questions about how cells operate, drilling down to the constituents of cells and how they get their properties, they will be directed to the chemistry department. If we then interrogate the chemist about the basis of their explanations, asking how the basic principles of chemistry and the properties of its constituents have come to be, we are directed to the physicist. The physicist is in a unique position, as they are expected to have the final answers!

With our understanding of how the disciplines build off each other, we can now see that when we say “modern science has convened towards physicalism” what we really mean is “modern science, through the principle of reductionism, indicates that all phenomena ultimately reduce to physical phenomena and the physical is sufficient to explain all aspects of reality”. We should note that reductionism is not universally accepted, and some thinkers like Paul Davies suggest holistic or teleological explanations without violating physics, but ultimately the assumption-based structural network is built into science whether we call it reductionism or by another name. What is clear, though, is that as we go up the chain of abstraction we quickly find ourselves far removed from changes to our understanding of the more fundamental fields. It may be that biology reduces to physics, but if string theory were to be embraced, or new quantum effects discovered, this would have little direct impact on the field.

So, the results of modern medicine, computers, and most discoveries are attributable to the structure of our scientific system and methodology, which is built to result in progress, and not to the truth value of its philosophical axioms. Consider the idealist who argues that all phenomena, indeed existence in its whole, are based upon a mental and/or immaterial basis. The idealist may take no issue with the explanations of physics. Rather, they insert a more fundamental level to the assumption hierarchy below even that of physics, replacing the axiom of physicalism with idealism while keeping the scientific system intact. The phenomena of physics, argues the idealist, are really just an abstract system and not a demonstration of a physical reality, as the basis of existence is really the mind. The physicist then, when probed enough, would direct their interrogator to the “mind-scientist”! To justify that there can be a level more fundamental than physics we should note an important point: the modern physicist cannot explain why there is something rather than nothing. Indeed we have theories of cosmology, but these refer to increasingly accurate predictions about how the physical universe evolved in its very first moments, perhaps even transcending the question of a temporal beginning altogether by blurring the distinctions between space and time in those immense early conditions. Yet despite the awe-inspiring ability of physics to probe such aspects of our physical reality this is not some sort of ultimate explanation. Even with continued progress, such as a breakthrough in string theory, we will still be evading the question of how a physical existence came to be at all! The result cascades up the hierarchy as a lack of any complete explanation for how there is physical existence at this moment and there seems to be no sign of how physics in its current form could ever tackle such a question. With a sense of resignation unbefitting of the scientist, some have even suggested that the question is forever beyond the ability of science.