Cognitive Computing 2012 The computer and the mind DUALISM Professor Mark Bishop

On metaphysics The Cognitive Computing MSC is not a philosophy degree.... however, as basic philosophical notions infuse cognitive science, some familiarity with a few basic concepts from philosophy is essential. Metaphysics is not – as is commonly thought – the science of the immaterial. In philosophy metaphysics is concerned with examining the fundamental nature of being and the world. In metaphysics the different kinds [or ways] of being are calledcategories of being, or simply categories. 01/04/2014(c) Bishop: An introduction to Cognitive Science2

On ontology Ontology fundamentally concerns the study of being and existence. Ontology enquires if some categories of being are fundamental. and, if so, in what sense the items in those categories can be said to be. Ontology is the inquiry into being in so much as it is being (being qua being) or into beings insofar as they exist (being qua existence) and not the particular facts that can be obtained about beings insofar as they exist them or the particular properties of them. 01/04/2014(c) Bishop: An introduction to Cognitive Science3

01/04/2014(c) Bishop: An introduction to Cognitive Science4 Dualism Dualism was an early metaphysical attempt to provide answers to questions of the form: What kind of thing is mind (if anything)? How is the mind (the mental) related to the body and the world? What characterizes the mental? Most generally, dualism expresses the view that, reality consists of two fundamentally disparate parts. More specifically in the philosophy of mind it is the belief that, the mental and physical are ontologically distinct (fundamentally different in kind; different categories of being); thus the mental is [at very least] not identical with the physical.

01/04/2014(c) Bishop: An introduction to Cognitive Science5 Causation and dualism Interactionist dualism Mental phenomena and material entities comprise two distinct categories of being; Each can have causal effects on the other. Epiphenomenal dualism Mental phenomena and material entities comprise two distinct categories of being; But mental phenomena do not cause material effects - despite widespread belief that they appear to.

01/04/2014(c) Bishop: An introduction to Cognitive Science6 Types of dualism Substance dualism (from Descartes) The view that the mental and the physical are ontologically distinct: The mental and the physical comprise two different categories of being: mind-stuff and body-stuff. Property dualism The view that the mental and the physical comprise two fundamentally distinct classes of property that are co- instantiated in the same objects (e.g. brains).

01/04/2014(c) Bishop: An introduction to Cognitive Science7 Substance dualism (1) Mind-stuff and body-stuff are two categories of being: Res cogitans: an immaterial substance without spatial dimensions whose essence is to think. Res extensa: a physical substance that has extension and location in space. It is incapable of thought. Its essence is to fill space. Hence the perceiving subject is ontologically distinct (and separated) from the perceived object. I.e. Mental items represent things, distinct from themselves. Perception, in contrast to naïve realism, is thus indirect; the mind access representation of things not the things in themself. The brain (res extensa) sends signals to mind (res cogitans) which invokes the mental items used in perception and cognition. Conversely mental items can invoke brain states which translate to motor events.

01/04/2014(c) Bishop: An introduction to Cognitive Science8 Dualism as a representational theory of mind In representational theories of mind cognitive states are relations to mental representations which have content. A cognitive state is a state (of mind) denoting knowledge; understanding; belief etc. Cognitive processes are mental operations on mental representations.

01/04/2014(c) Bishop: An introduction to Cognitive Science9 Substance dualism: the argument from skeptical doubt Mind or any mental state could exist whether or not (and however) any bodies (material things) exist See Descartes Second Meditation, Cogito, ergo sum I can doubt that the material human being Mark Bishop exists. Descartes and the evil demon… But I cannot doubt that I exist. … I cannot doubt that I am doubting. Therefore it is possible that I could exist and the material human being Mark Bishop not exist.

01/04/2014(c) Bishop: An introduction to Cognitive Science10 Substance dualism: the argument from clear and distinct ideas I can clearly and distinctly perceive the mind apart from the body. Therefore the mind and the body must be distinct. But are we really aware of everything in ones mind (all the mind stuff) or in ones body (all the body stuff)? If not, how can we be sure we clearly and distinctly perceive the mind apart from the body?

01/04/2014(c) Bishop: An introduction to Cognitive Science11 Substance dualism: the argument from divisibility Matter (e.g. my body) is divisible; it must be as it is extended in space. The mind is NOT divisible; it is a category mistake to apply the property of divisibility to mental properties. A category mistake, or category error is a semantic or ontological error by which a property is ascribed to a thing that could not possibly have that property, (Ryle, G, (1949), The Concept of Mind). Therefore the mind is not material! But is it a category mistake to consider splitting the mind in two? It is certainly at least conceivable to envisage two half-minds (split temporally or by content) each containing half of all experience and knowledge..

01/04/2014(c) Bishop: An introduction to Cognitive Science12 The causal interaction argument against substance dualism Casual Interaction: we need a plausible account of the interaction between mind & body. Any adequate metaphysics of human beings as a union of two things (mind + body) must provide a plausible account of their interaction. A-priori substance dualism entails that mental substance has no properties in common with physical substance. Acts of thinking need no material thing to have them. Acts of thinking need none of the properties of material things: spatial extension, position etc. Yet causation entails at least some similarity between cause & effect. Hence SD cannot account for causal interaction and hence does not provide an adequate metaphysics of mind.

01/04/2014(c) Bishop: An introduction to Cognitive Science13 Property dualism The view that the mental and the physical comprise two differentclasses of property that are co-instantiated in the same objects (e.g. brains). One aspect of mind is material; as it is instantiated by the brain and the world constitutes the mental properties of the brain. But another aspect of mind - mental properties - are non-physical: Mental properties are in some sense emergent on brain states; And co-occurrent with brain properties. However we can never simply reduce mental properties to brain properties.

01/04/2014(c) Bishop: An introduction to Cognitive Science14 On the wetness of water An analogy to the property dualism of the mental is the phenomenal feel of the wetness of water. The wetness of water is real and co-occurrent with specific properties of hydrogen & water. However we cant reduce the wetness of water to the physical properties of hydrogen & oxygen; Contrast the hardness of diamond which can be deduced from the physical properties of carbon molecules.

01/04/2014(c) Bishop: An introduction to Cognitive Science15 Property dualism: the argument from reduction Brain states are material and casually linked to subjective experience. But subjective experience {e.g. the wetness of water} cannot be deduced from, reduced to, or identified with, brain states as brain states have irreducibly material not mental properties {e.g. hydrogen and oxygen and the wetness of water}. Hence mental properties are not reducible to material properties.

01/04/2014(c) Bishop: An introduction to Cognitive Science16 Property dualism: the argument from introspection 1. The mental contents of subjective experiences are knowable to me by introspection. 2.Properties of my brain states are not knowable to me be introspection. 3. Hence the mental contents of subjective experiences are not properties of brain states. But does [2] presupposes what [3] is meant to establish;begging the question?

01/04/2014(c) Bishop: An introduction to Cognitive Science17 Property dualism: the argument from knowledge Frank Jackson - The epistemic argument - Mary the colour blind neuroscientist.. Suppose Mary knows everything about brain states and their properties, (there exists a complete neuroscience). Suppose Mary doesnt know everything about sensations and their properties, (she has lived all her life in a grey room), but she has read up all about the brain states of seeing, say, a red tomato, (though she doesnt know what it is like to SEE a red tomato). Hence sensations (& their properties) are not reducible to brain states (& their properties). i.e. Psychology cannot be reduced to neuroscience.