While posting on a faith & philosophy discussion group, a question was raised about reductionism. Does all of human experience stem from neurons only? I personally believe so, although I agree that one should not try and explain the whole of reality on one small aspect of reality. A holistic approach is definitely needed. However, my approach follows the ideas of John Searle, a mind philosopher who argues against reductionism and dualism. His approach is not reductionistic in the strictest sense, because it considers the impact of complexity. The human brain contains billions of neurons. This is an incredible amount! Synapses within the brain fire ten million billion times a second. Like a single molecule of water, a single neuron on its own doesn't express many properties. But if we add billions of water molecules together, for example, they exhibit unique properties that a single molecule of water cannot express on its own (e.g., wetness, coolness, etc). As we add more water, complexity increases, and additional properties enter the system: such as capillary action, complex weather systems, and hurricanes.
Likewise with neurons: if you consider only one neuron, there is nothing special about it. If you consider a couple of million neurons, the complexity of the situation can be explored through neurobiology. But if you consider the entire brain - all the billions of neurons - new properties emerge from the system, such as consciousness, feelings, emotions and maybe even the mind. To understand this level of complexity you need to use tools such a psychology. If you consider trillions of neurons (i.e., many millions of brains), new properties emerge that only be explained by sociology, and new properties at this level might include morals and culture, and maybe - as Richard Dawkins argues in his essay, Viruses of the Mind - religion.
Different tools and different fields of study need to be used to explain different levels of complexity of human nature, but I still believe that all these different levels of wonderful complexity have their origins in the humble neuron, but not on one neuron alone, or just a few. The levels of complexity have their origins in many billions (or trillions) or neurons that interact to form complex neural and social networks - in other words, many intertwined layers of complexity. My personal philosophy is one of finding meaning this complexity, and celebrating it to its fullest.