Jaegwon Kim Physicalism Essay

Essays in the Metaphysics of Mind

Jaegwon Kim


This book is a collection of 14 essays; 11 of these have been previously published and three are new. All but one of them have been written since 1993 when my essay collection Supervenience and Mind appeared. Essays used in the monographs, Mind in a Physical World and Physicalism, Or Something Near Enough, have been excluded. The book begins with four essays on emergence and related issues; in one way or another, each of these essays raises difficulties for the idea of emergence. In particular, the last essay casts serious doubt on the intelligibility of the very idea of ontological emergence ... More

This book is a collection of 14 essays; 11 of these have been previously published and three are new. All but one of them have been written since 1993 when my essay collection Supervenience and Mind appeared. Essays used in the monographs, Mind in a Physical World and Physicalism, Or Something Near Enough, have been excluded. The book begins with four essays on emergence and related issues; in one way or another, each of these essays raises difficulties for the idea of emergence. In particular, the last essay casts serious doubt on the intelligibility of the very idea of ontological emergence (distinguished from epistemological emergence). These essays are followed by two essays on explanation of action. Both stress the centrality and priority of the agent's first‐person point of view in understanding actions. The second of the two, which is new, develops an agent‐centered normative account of action explanation, in opposition to the prevailing third‐person approaches such as the causal and nomological models. The next group of four essays addresses various issues about explanation, such as explanatory realism, explanatory exclusion, reduction and reductive explanation, and what a philosophical theory of explanation should be like. Mental causation and physicalism are the concerns of the next three papers. One of these examines Donald Davidson's defense of mental causation within his anomalous monism. Another discusses Sydney Shoemaker's recent analysis of realization (the “subset view”) and his defense of mental causation. The last essay of the book addresses the issue of laws in the special sciences, offering three arguments to show that there are no such laws. The first begins with a consideration of Davidson's argument for the claim that there are no strict laws about the mental; the second builds on J.J.C. Smart's observations on biology and its relation to physics; and the third is based on my earlier work on multiple realization.

Keywords: emergence, emergentism, layered model, downward causation, supervenience, action explanation, first‐person point of view, agent's point of view, normativity, explanation, explanatory exclusion, reduction, reductive explanation, theory of explanation, understanding, law, special science, anomalism of the mental, epiphenomenalism, anomalous monism, physicalism, mental causation, nonreductive physicalism, realization, subset realization, second‐order realization

Bibliographic Information

Print publication date: 2010Print ISBN-13: 9780199585878
Published to Oxford Scholarship Online: January 2011DOI:10.1093/acprof:oso/9780199585878.001.0001


Affiliations are at time of print publication.

Jaegwon Kim, author
Brown University
Author Webpage


Information is neither matter nor energy. It is sometimes embodied in matter and sometimes communicated as pure energy. It is the scientific basis for an immaterial, causally open, non-physical mind that can nevertheless affect the physical world. Information is the
modern spirit.

Recap of the Problem of Mental Causation according to Kim.

While the original mind-body problem was simply the puzzle of how an immaterial mind could cause a material body to move, lately the problem of mental causation has been recast as the logical resolution of one basic premise and a conclusion, which we might call the standard argument against mental causation:
  1. The only causes are physical causes. (These causes need not be deterministic. An indeterministic quantum statistical event gives us the probabilities for subsequent events, "causing" them in a way that is not pre-determined.)
  2. Therefore, mental events cannot cause physical events.

The Emergence of Life from Matter and Mind from Life.

According to British Emergentism, there is a hierarchy of levels of organizational complexity of material particles that includes, in ascending order, the strictly physical, the chemical, the biological, and the psychological level. As we have seen, upper hierarchical levels have the power to influence motion in ways unanticipated by laws governing less complex kinds and conditions concerning the arrangements of particles. Emergentism is committed to the nomological possibility of what has been called "downward causation," control by an upper level of the component particles of the lower levels. We can now demonstrate that the Emergentists' hypothesis is actually realized in biological systems. The informational analysis of non-reductive physicalism must show exactly how information does not move in the upward direction between hierarchical levels (fundamentally because noise in the lower level makes motions incoherent), but that information does move down as the higher-level information-processing system uses it to manipulate individual physical particles (maintaining a high signal-to-noise ratio in the upper level), as the British empiricists imagined.

Quantum Randomness Blocks "Bottom-Up" Causation,
Information-Processing Structures Enable Downward Causation

We shall now see that quantum and thermal noise breaks any upwardly causal deterministic chains between the physics of the atomic and molecular level and the biophysics of the organic world. It also breaks any upward deterministic chains between the neurobiological brain and the mind, replacing them with a statistical causality that provides us with what William James called “some looseness in the joints.” We present two processes that exhibit randomness in the component atoms and molecules, thus blocking any organized upward influences. The first is present in every biological cell. The other is critically important in the operation of neurons. The first separates the living from the simply material. The latter is at the mind/brain boundary.

Ribosomes Build Hemoglobin from Randomly Moving Amino Acids (Life from Matter)

The twenty amino acids move about randomly in a cell, the consequence of thermal and quantum noise. Attached to them are tiny bits of transfer RNA, each with three letters of the genetic code that identify them. They bump randomly into the ribosome, which may be moving along a sequence of the genetic code written in messenger RNA sent from the cell nucleus, which has noticed that more of a specific protein or enzyme is needed. This random motion shows us that no organized or coherent information is present in the unattached tRNAs that could cause something from the bottom up to emerge at a higher level.

[Look at the animation of mRNA translation] Notice the absurdity of the idea that the random motions of the transfer RNA molecules (green in the video at right), each holding a single amino acid (red), are carrying pre-determined information of where they belong in the protein. It is the information processing of the higher-level ribosome that is in control. As the ribosome moves along the string of mRNA, it reads the next three-letter codon and waits for a tRNA with the matching anti-codon to collide randomly. With over 60 codons for the 20 amino acids, it might be some time before the desired amino acid shows up. Note that it is the high speed of random motions that allows this process to proceed rapidly. Consider the case of hemoglobin. When a ribosome assembles 330 amino acids in four symmetric polypeptide chains (globins), each globin traps an iron atom in a heme group at the center to form the hemoglobin protein. This is downward causal control of the amino acids, the heme groups, and the iron atoms by the ribosome. The ribosome is an example of Erwin Schrödinger's emergent "order out of order," life "feeding on the negative entropy" of digested food.
When 200 million of the 25 trillion red blood cells in the human body die each second, 100 million new hemoglobins must be assembled in each of 200 million new blood cells . With the order of a few thousand bytes of information in each hemoglobin, this is 10 thousand x 100 million x 200 million =
2 x 1020 bits of information per second, a million times more information processing than today's fastest computer CPU. The ribosome is an information-processing biological system that has emerged from the lower level of chemistry and physics to exert downward causation on the atomic and molecular components needed to manufacture hemoglobin.

Ion Pumps in Neurons Organize Randomly Moving Individual Atoms (Mind from Life)

When a single neuron fires, the active potential rapidly changes the concentration of sodium (Na+) ions inside the cell and potassium (K+) ions outside the cell. Within milliseconds, thousands of sodium-potassium ion transporters in the thin lipid bilayer of the cell wall must move billions of those ions, two or three at a time between inside and outside the cell wall, to get the neuron ready to fire again. All the individual ions, atoms, and molecules in the cell are moving rapidly in random directions. The indeterministic motions of the ions randomly move some near the pump opening, where quantum collaborative forces can capture them in a lock-and-key structure. The idea that the physical/chemical base level contains enough information in the motion of its atoms and molecules to cause and completely explain the operations of the higher levels of life and mind is simply absurd. The emergent biological machinery of a sodium-potassium pump exerts downward causation on the ions, powered by ATP energy carriers (feeding on negative entropy). The sodium-potassium pump in our neurons is as close to a Maxwell's Demon as anything we are ever likely to see. When many motor neurons fire, innnervating excitatory post-synaptic potentials (EPSPs) that travel down through the thalamus and the spinal cord where they cause muscles to contract, that is as literal as downward causation gets between the mind and the body. When the emergent mind decides to move the body, mental causation is realized as downward causation.

The Information Solution to the Problem of Mental Causation.

Information philosophy understands mental events as immaterial thoughts, which are normally only unrealized possibilities for action. Thoughts are embodied in the neural information structures of the brain, where they are stored along with memories of past experience. As such, they are physical and are temporarily even material, in some sense. But when they are transferred (communicated) to other parts of the brain, out to other minds, or for storage in the external environment, thoughts are converted from a material substrate to various forms of energy. Temporarily, they are quite non-material, as philosophers for centuries have imagined thoughts in an immaterial mind might be. Once stored, they are again embodied in matter. Of course, thoughts or ideas can be unpredictably altered before storage, by noise in the communication. They can also be altered randomly by irreducibly indeterministic errors in the retrieval of the information. Here lies the basis for creative mistakes, to be evaluated by a process of intelligent selection. (As Augustine noted, the Latin intelligere means "to select.") The information solution to the mind-body problem can be interpreted as providing a non-reductivephysical interpretation of mind. This model of mind supervenes on the neural brain structures that embody the information (while it is being stored). But the intellectual content of the information is not the resultant of whatever physical processes are coming from lower layers in a hierarchical structure. The physical brain is a plastic storage medium adequately determined to store the information content of these immaterial thoughts, and normally to store it accurately. With reference to popular (if flawed) computational theories of mind, we note that the "software" contents of a computer program, as well as the execution of the program, is in no way determined or "caused" by the computer "hardware." Similarly, ideas are not determined by the ink on a printed page or the pixels on a computer screen, but by the human minds that put them there.

"Bottom-up" Physical Processes Are Not Deterministic

When small numbers of atoms and molecules interact, their motions and behaviors are indeterministic, governed by the rules of quantum mechanics.

Note that this is the reverse of the normal view that microscopic processes are time reversible and deterministic, where macroscopic processes for unaggregated gas particles are statistical and irreversible.

However, when large numbers of microscopic particle get together in chemically or gravitationally bound aggregates, the indeterminacy of the individual particles gets averaged over and macroscopic adequately deterministic laws "emerge." Determinism is an emergent property that shows up in the macroscopic world. The "laws of nature," such as Newton's laws of motion, are all statistical laws, however close they appear to being certain. They "emerge" when large numbers of atoms or molecules get together. For large enough numbers, the probabilistic laws of nature approach practical certainty. But the fundamental indeterminism of component atoms never completely disappears. It therefore follows that physical brain events are not pre-determined by the events in lower hierarchical levels, not events in the base physical level, nor even in the biological level. And the world is not "causally closed" by deterministic physical laws of nature, as assumed by so many philosophers (e.g., Feigl, Smart, Kim). Moreover, since some "mental events" are large enough information structures to be adequately determined, these mental events can act causally on lower biological and physical levels in the hierarchy, in particular, the mind can move the body and all its contained physical particles, thus solving the mind-body problem. A specific example of the mind causing an action, while not itself being caused by antecedent events is the following. Faced with a decision of what to do next, the mind considers several possible alternatives, at least some of which are creatively invented based on random ideas that just "come to mind." Other possible alternatives might be familiar options, even habits, that have frequently been done in earlier similar situations. All these alternatives show up as "neural correlates" - brain neurons firing. When the alternatives are evaluated and one is selected, the selected action results in still other neurons firing, some of which connect to the motor cortex that signals muscles to move the body. Apart from the occasional indeterministic generation of creative new alternative ideas, this whole causal process is adequately determined and it is downwardly causal. Mental events are causing physical body events.
Quantum Physics and the Problem of Mental Causation". Presented June 6, 2013 at a conference in Milan on "Quantum Physics Meets the Philosophy of Mind".

For Teachers

Stanford Encyclopedia of Philosophy


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