Towards a Naturalistic Theory of Mind EMERGENCE AND

Towards a Naturalistic Theory of Mind EMERGENCE AND DOWNWARD CAUSATION

PHILOSOPHY OF MIND � One of the major segments of contemporary philosophy is grouped under the heading, “philosophy of mind. ” This area investigates some of the following questions: � � � What is the nature of consciousness? How do cognitive processes (perception, imagination, memory, will, etc. ) work? Do human agents have freedom of choice? What is the ontological status of mental states and phenomenal properties? What is the nature of mental content? There a number of different answers to these questions; some have been more willing to accommodate natural science, while others have been less willing.

NATURALISM, MIND, AND EMERGENCE � � One approach to the nature of mind has been to resist any naturalistic encroachment on theory of mind: mental states (thoughts, feelings, ideas) are just different than the rest of nature. This view is seen most clearly in Rene Descartes’ insistence on the duality of mental substance and material substance. A more recent version can be seen in Edmund Husserl’s critique of psychology in the late 19 th century. Though there is a genuine difficulty in incorporating our subjective experience of the world in an objective account of the way the world is, non-naturalist theories of mind seem to be fighting a losing battle. The theory of emergence offers a way of conceiving of mind that preserves some of its uniqueness while incorporating it into a complete story of the natural world.

WHAT IS EMERGENCE? Emergent properties are properties of a system that arise out of the fundamental elements in the system, but do so in a way that is either unexpected or inexplicable on the basis of those fundamental elements.

EMERGENCE AND COMPLEXITY � � Sometimes emergence is tightly linked to complexity in the sense that complex systems give rise to unpredictable patterns, given relatively simple initial conditions. In mathematics (or systems theory): � � � Complex functions that iterate successively often generate regular patterns. Even though these functions are deterministic, i. e. , every iteration can be determinately linked to earlier iterations, the patterns that are generated cannot be predicted. In Chaos theory, the unpredictability of patterns is a result of the sensitivity of the system to minute differences in initial conditions (e. g. , butterfly effect). Emergent properties are also often the result of limiting conditions, or “pruning laws, ” that have no explanation from the perspective of the emergent base (the basic components of the system). A good example of this is “The Game of Life. ”

STRONG VS. WEAK EMERGENCE � Weak emergence: properties on a higher level are unpredictable from the perspective of the lower level, they are surprising and interesting, but they can be explained entirely and deduced from the lower level properties and laws. � Strong emergence: properties on a higher level in principle cannot be deduced from properties at a lower level.

WHAT DO WE WANT OUT OF AN EMERGENTIST THEORY OF MIND? � All theories of emergence provide the idea that something unique and surprising occurs at a higher level that cannot be predicted at a lower level. � � Emergence thus confirms the novelty of mental properties. Thoughts, beliefs, perceptions, and desires are not just electrochemical interactions. However, weak emergence would suggest that mental properties can ultimately be deduced from electrochemical interactions in the brain, but in complex and surprising ways. Strong emergence—which I favor—would say that those mental properties are entirely novel and can in no way be deduced from electrochemical interactions in the brain. I believe this is specifically true for consciousness, i. e. , that conscious experience feels the way it does (that red looks red, for instance). in the case of mental properties, it is clear that those properties (thoughts, beliefs, wishes) produce physical actions. For instance, my belief that it is raining will cause me to put on a jacket or carry un umbrella. � � We want mental properties to be not only non-reducible to physical properties but also “causally efficacious. ” We want emergent properties to causally interact with lower level properties, to produce real changes in the physical world.

STRONG EMERGENCE I claim that we want out of a theory of mind is something like “strong emergence” or emergence with downward causation. � In other words, we don’t want mental properties to be simply emergent, but we want them to be causally efficacious as well. � My aim in this presentation will be to explain what emergence with downward causation is, and to show: � 1. 2. That emergence is a plausible theory of not only mind, but of many other natural phenomena. That downward causation is at least as intuitively appealing as its converse, namely, epiphenomenalism.

FORMAL STATEMENT ON EMERGENCE � Given a system P with a set of properties and rules governing relations between those properties (ϕ), we say that ϕ is emergent on ψ (called its “emergent base”) if and only if ϕ exhibits properties and relations that could not be predicted (weak emergence) simply on the basis of ψ or cannot be deduced in principle (strong emergence) by ψ. Ontological implication: “levels” of objects, properties, and laws. � Epistemological implication: each level must be understood on its own terms, though it may also be connected (according to the principle of emergence, if there is one) to a more fundamental level. �

ONTOLOGICAL LEVELS � Given an emergentist framework, we might imagine the world as composed of an array of emergent levels. � At the most fundamental level, we would have subatomic particles and fundamental physical forces. � At the next level, we would have atoms, then molecules, then cells, multicellular organisms, and so on. � The claim of emergence is that each new level of organization introduces properties and rules of relation that are either novel and surprising or entirely independent of lower levels.

EMERGENCE AND THE SPECIAL SCIENCES � � Notice that this view of emergence is actually exactly what we find in practice in the sciences. While physics is thought of as a general science, applicable to all physical events and phenomena, the other sciences have laws and properties that we cannot explain fully through the physical sciences. � � � Chemistry, Biology, Psychology, Economics, Sociology, etc. As a theoretical question, we might ask if a superhuman physical scientist (possessing a complete physical description of the universe) could, for instance, derive economic laws from physical laws? How would he do it? � � At least one response to this is that he would have to discover laws that explained, for instance, economic theory in terms of psychology, further laws explaining psychology in terms of biology, further laws describing psychology in terms of chemistry, and still further laws describing chemistry in terms of physics. But presuming that such “bridge laws” exist, do they really make economics nothing but physics?

EMERGENCE AND SUPERVENIENCE � The relationship of emergent properties to emergent bases is typically described in terms of supervenience. � Roughly, A supervenes on B iff. there can be no change in A without a corresponding change in B. � Varieties of supervenience: � Logical supervenience: it is logically impossible for A changes to exist absent B changes (consider the relationship of a chord to notes). � Nomological supervenience: it is impossible within the laws of nature for A changes to exist absent B changes. �I believe that minds nomologically supervene on brains.

EMERGENCE AND DOWNWARD CAUSATION � Given supervenience, philosophers typically refuse to accept the idea of downward causation. � � � Consider a universe with only two different kinds of properties, A and B. (For purposes of imagining the scenario, think of B properties as the letters and words in a book and A properties as the molecular composition of ink and paper. ) Every change in the content of the book (every variation in B properties) is the result of changes in the molecular compositions of ink and paper (variations in A properties). In other words, the existence of words in the book are entirely dependent upon the amount of ink and paper that composes the book. You don’t get changes in the content of the book without altering the amount of ink and paper in the manufacture of the book. Here it should be clear that the letters and words in a book logically supervene on the composition of ink and paper. (You can have the same letters and words in different formats, clearly, but then they would not be a book in the appropriate sense. ) The point here is to say that the letters and words are fixed by the composition of paper and ink and not the other way around.

EMERGENCE AND DOWNWARD CAUSATION � � � Philosophers like to imagine that the natural world is causally closed, i. e. , there are no “new” causal powers other than the ones that would be described by an ideally complete fundamental physics. Since emergent properties are novel and unpredictable, giving these properties causal powers appears to violate causal closure. It’s like magic! Alternative view: � � Consider emergent properties, B, on basic properties, A. Think of B properties as those properties that A properties have when they are grouped together in a certain way. Synchronically, there will be a causal arrow will going from the set of A properties to the B properties that emerge from them. The question is: what happens diachronicall?

EMERGENCE AND DOWNWARD CAUSATION (1) B 1 A 1 (3) B 1 A 1 B 2 A 2 (2) B 1 A 1 B 2 A 2 (1) and (2) are unacceptable because they result in the overdetermination of either A 2 or B 2 states. This would make one or the other causal powers redundant and as a result there would be a real question about which was truly the cause. But what about option (3)? Could this be a formula for the causal efficacy of emergent properties, i. e. , to say that once an entity expresses emergent properties it now acts in an entirely new way, as a composite of its emergent properties and its emergent basis together?

EPIPHENOMENALISM � � Consider the alternative to downward causation. Assuming that something like emergent properties actually exist, and given that they cannot be real causes, i. e. , they do not have unique causal powers (cases 1 and 2 above), then emergent properties must be “epiphenomenal. ” � � This view suggests that though emergent properties exist, they exist in the same way the shadow of my hand exists. They are there, but they don’t do anything! If you believe in epiphenomenal properties, you might as well believe in ectoplasm, gremlins, and fairies. In other words, why not just make believe that there an infinite number of things in the universe, they just don’t DO anything. I believe that epiphenomenalism is an absurd result. If the view of emergence results in epiphenomenalism, then it must be wrong. Put otherwise: real qualities must have causal powers or else they are not real.

VARIETIES OF EMERGENCE

THE EMERGENCE OF THE PHYSICAL UNIVERSE

THE EMERGENCE OF THE PHYSICAL UNIVERSE � Much remains unknown about the first microseconds of the universe. � � � The temperatures and pressures theorized in the Big Bang ensure that the laws of physics do not apply, it is a “singularity. ” It is not known what forces are responsible for the initial rapid expansion of the universe. It is not known why matter is distributed in different densities. This last factor is necessary for the universe to appear as it does today. � A uniform distribution of initial matter would ensure a universe that matter would remain uniform (as gravitational pull in any direction would be canceled by gravitational pull in opposing directions. ) � Stars, galaxies, planets, etc. are the result of variations in the density of the initial, inflationary universe. � In other words, the universe we see to day is an emergent property of the density differentiations in the inflationary universe. �

EMERGENCE OF THE CHEMICAL FROM THE PHYSICAL Chemistry is the science of molecular compounds, which are the result of bonds between atoms. � Chemical properties demonstrate emergence. � Consider, water: H 2 O. � Hydrogen is a gas that becomes a liquid at -259. 14°C (density of. 089 g/m); Oxygen is a gas that becomes a liquid at -218. 79°C (density of 1. 429 g/m); but water is a liquid that boils at 100°C and freezes at 0°C (at sea level) (its density varies with temperature, becoming less dense as it gets colder, but it is around 1 g/m at about 4°C). ° � There are many other properties of water that are quite unique and important for biochemical processes: surface tension, capillary action, “universal solvent. ” �

CHEMICAL EMERGENCE � � � The reason why a molecule of water, for instance, can have properties that are entirely different from the properties of its constituent atoms is because of its chemical structure. The shape of molecular compounds is determined by the bonds between atoms. The structure of atoms and molecules is governed by the “Pauli exclusion principle, ” which holds that— stated at the atomic level—no two electrons can have the same quantum state. (This explains why electrons occupy a higher shell. ) Essentially, this means that chemical and atomic structures are the result of an entirely new rule that applies to electrons only when they are in larger systems, either atomic or molecular. In other words, electrons behave differently in some situations, and this gives rise to chemical structure. Chemical structure is responsible for most of the properties that gross matter possesses.

THE IMPORTANCE OF CHEMICAL STRUCTURE � Chemical bonds are essential to natural processes: � � all chemical processes and the “information” carried by chemicals in biochemical interactions are all governed by chemical structure. Also, hardness, softness, liquidity, crystaline formations are all a product of the bonds that make up chemical structures.

OOBLECK, THE NON-NEWTONIAN FLUID

OOBLECK? ! � When corn starch and water are mixed, they create a compound that has unusual properties because of the peptide bonds that the starch introduces to water: � When minimal force is applied, the substance acts like a fluid. � When greater force is applied, the substance behaves like a solid. � Many of the essential elements of life are like this: they are the result of unique properties generated by molecular composition.

EMERGENCE OF LIFE � Single cell organisms and multicelled organisms show a new level of complexity. � Now, chemical compounds are grouped together in functional groups that play unique roles in a larger system. � And the cell now has properties that, though they depend on and utilize chemical structures, are entirely new.

FUNCTIONAL IDENTITY OF CELLS In larger organisms, cells exhibit functional differentiation: some cells organize into a heart, liver, stomach, blood vessels, etc. � In order for a cell to play its role in the organism, it must “know” what kind of cell it is and how it can play its role. � This cellular identity appears to be determined by genetic determinants as well as chemical messages between cells. � � As an example, cancer appears to be the result cells that (through some genetic mutation) lose their sense of identity and functional contribution to the organism. Cancer cells “go rogue” functioning rapidly reproducing without awareness of the negative impact on the organism

FUNCTIONALITY AND ALTRUISM Slime mold (dictyostelium) is sometimes cited as an example of cellular “altruism. ” This amoeba begins as a single-celled organism that organizes into a multi -celled colony, where different cells assume different roles. For instance, some cells occupy the role of “stalk” enabling spores to disperse greater distances. These cells are acting altruistically in the sense that they serve a larger purpose.

EMERGENCE OF SOCIAL ORGANIZATION Eusocial creatures, like bees and termites, exhibit behavior in groups that is similar to the behavior of cells in multi-celled organisms. They create elaborate structures and perform complex tasks with highly differentiated roles.

SWARMING STARLINGS

ARE THESE ORGANIZATIONS CONSCIOUS? � Though high levels of social complexity are found everywhere in nature, it is not clear to what degree they are the result of conscious design. � Perhaps we can call this behavior conscious in a minimal sense, but it is not likely conscious in the full sense that it is the result of rational thought. � Similarly, human behavior is not entirely conscious, i. e. , the result of rational thought.

TRAFFIC FLOW

HUMAN BEHAVIOR AS AN EXTENSION OF NATURAL ORGANIZATION � When we drive in traffic, we often assume that traffic congestion is the “fault” of “bad drivers. ” � But traffic flow actually appears to be a fairly regular and predictable, if complex, behavior. � It is likely that traffic congestion is no more the “fault” of any one person’s driving habits than the swarming starlings are the result of conscious choreography.

CONSCIOUSNESS AS AN EMERGENT PHENOMENON � � � At some point, however, full consciousness, in the sense of a highly developed sense of self, planning for the future, imagination, and calculation emerges from the physical and chemical processes in the human body. Moreover, consciousness requires experience. The world suddenly feels a certain way to a certain kind of entity. All of our sensory experiences come with a peculiar feel that seems entirely independent of the causal basis for that feel. For consciousness to be an emergent property in the sense we are discussing, it would entail an entirely new set of properties that could not be predicted simply on the basis of the physical and chemical processes in the body.

CONSCIOUSNESS, STRONG EMERGENCE, AND DOWNWARD CAUSATION � � I have suggested that the concepts of downward causation and emergence will help to explain how consciousness fits into the natural world without losing the uniqueness and irreducibility of conscious experience, i. e. , that mind is not just the same thing as brain and that minds are causally active in shaping the world. Looking back, however, we might wonder if consciousness is really something different from chemical structures, cells, multicellular organisms, social organizations, and so on. � � � Are the examples from the natural sciences strongly emergent or weakly emergent? Is consciousness strongly emergent or weakly emergent? If consciousness is weakly emergent, do we lose a robust sense of free will?