Last Updated on May 6, 2015, by eNotes Editorial. Word Count: 569
Part 1 of Neurophilosophy aims to introduce philosophers to some elementary neuroscience. The book opens with a historical sketch of the science of nervous systems, beginning with Galen, the third century b.c.e. Greek anatomist and physician, and ending with the invention of the electron microscope in the 1950’s. Although this overview is organized chronologically, the historical details nonetheless suggest a unifying theme: the progress of science away from vitalism and toward a mechanistic materialism.
As Churchland explains, the vitalists viewed the motion of muscles in terms of a psychic breath of air, or pneuma. Although through the centuries there were occasional refinements to the theory, such as Descartes’s introduction of a mechanistic connection between the vital spirit and the body, vitalism remained scientific orthodoxy through the first half of the seventeenth century. At that time, the theory suffered its first real threat, stemming from the work of Dutch biologist Jan Swammerdam. In experiments on the leg muscles of frogs, Swammerdam was able to produce muscle contractions purely mechanically, thereby suggesting the superfluousness of vital spirits. Such experiments themselves were not enough to loosen the grip that vitalism held on the scientific imagination, but they did lead to further research, such as the nineteenth century work of Hermann von Helmholtz. A student of the father of modern physiology Johannes Müller, Helmholtz applied the law of conservation of energy to biology. As Churchland describes in some detail, this application produced experimental results showing that the chemical reactions ordinarily occurring in a human body were sufficient to generate all of the organism’s physical activity. There was no need, in other words, for a psychic spirit or breath of air. In this way, Helmholtz was profoundly influential in overturning the vitalistic conception and was responsible for ushering in the modern-day, mechanistic understanding of the nervous system.
In the hundred years between Helmholtz’s experiments and the invention of the electron microscope, what Churchland calls the “neuron paradigm” was established. Scientists developed a basic framework for neuroscientific research, and the science of nervous systems thereby began to blossom. After guiding her philosophical audience on a tour of early research into the neuron, Churchland abandons her historical approach. The remainder of part 1 involves a thematic discussion of theories concerning the functioning and anatomy of neurons. After summarizing scientific findings about neurons themselves, she provides a description of how these basic elements of nervous systems are configured into networks. Her discussion of the structure of nervous systems aims to refute the “bramblescape” theory, according to which such systems are fundamentally a hodgepodge of neurons. Someone who labors under the misconception that nervous systems are merely a hopeless tangle will quite naturally be skeptical about the promise of neuroscience. Thus, to defend the neuroscientific enterprise against such skepticism, Churchland carefully describes five different dimensions of neuronal organization: pathways, laminae, topographical maps, columns, and nervous-system development.
Churchland’s discussion of functional neuroanatomy also sets the stage for her discussion of the importance that philosophy has for neuroscience in part 2 of Neurophilosophy. As she writes,With so much known about the neuroanatomy and neurophysiology of nervous systems, what is now needed are theories of brain function that will begin to pull the data together, to pose new questions, and to compete for epistemological space.
Philosophy must play an essential role, Churchland thinks, with respect to the development of overarching theories that can guide neuroscientific research.