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Tallis in Wonderland

Cut-Price Dualism: ‘Properties Not Substances’

Raymond Tallis says a modern modified mind-body dualism still doesn’t work.

According to a recent survey, mind-matter dualism still enjoys significant support among Anglophone philosophers (‘Philosophers on Philosophy’, David Bourget and David Chalmers, Philosophers’ Imprint, 22:11, 2023). While it is less popular than materialism, its 22% rating surprised me. After all, failing to deal with the problems of Cartesian dualism has shaped much of the philosophical conversation since Descartes argued in 1642 that mind and matter were distinct and independent substances.

The most obvious objection – first expressed by Descartes’ pupil Princess Elizabeth of Bohemia – is that the mind (res cogitans) and matter (res extensa) do not seem to have the wherewithal to engage with each other. How could the impact of material events on the body trigger mental events that lack location? And how could mental events without location bring about changes in the material world, as when thoughts lead to actions? By what means is locationless mind associated with a specific body, such that conscious experiences are those of an individual subject inseparable from a particular portion of space-occupying flesh?

It is not, therefore, surprising that a version of materialism, where minds are envisaged as events or processes in the brain, was the preferred choice of more than 50% of philosophers in the survey. Mind-brain identity, however, brings troubles of its own. It seems to underplay the profound differences between experiences, thoughts, intentions and emotions on the one hand and rocks, trees, and dinner on the other - differences that had seemed to Descartes to justify mind and matter being allocated to ontologically different categories.

A Dualism Upgrade?

In recent times, dualism has been modified to address, or to avoid, the problems associated with getting minds and bodies to have anything to do with each other. Substance dualism has been displaced by ‘property’ or ‘aspect’ dualism. Mind and body, we are told, are properties of the same underlying, more fundamental, stuff.

Some thinkers argue that property dualism extends beyond conscious beings. For panpsychists (8% of the respondents in the survey), all matter, down to elementary particles, is associated with consciousness. According to the most widely accepted version of property dualism, however, mind is confined to those creatures that happen to have complex nervous systems. This localised property dualism drifts towards a belief, standard among materialist philosophers and a fundamental article of faith of many neuroscientists, that mind is identical with neural activity.

There are many problems with this would-be solution to the Cartesian challenge. I have discussed (nay, banged on about) them in previous columns where I have attacked a property-dualism that looks to brain processes to account for mind. Why are some parts of the nervous system (for example parts of the cerebral cortex) associated with consciousness while others (such as the spinal cord) are not? Why should travel (which of course broadens the mind) from one part of the nervous system to another enable otherwise purely physical neural activity to broaden into mind? How does the diverse activity in the brain become unified into moments of consciousness which themselves become unified over time into an enduring self? How could the brain – a material object enduring in tenseless time – give rise to the tensed time of the human subject recalling the past as the past and anticipating the future as its future? What is it about the patterns and quantity of nerve impulses that determines whether or not a material object awakens into a world, into itself, and into a world that it intuits as its world? How could sodium and potassium ions passing through semi-permeable membranes turn brains into places where material processes become their Cartesian twins?

Rather than go again over this rather well-trodden territory, I want to look more carefully at the very notion of brains, or some of their activity, having two aspects or two properties that are as fundamentally different from one another as mind and matter.

Let us deal first with the two aspects version of the mind-body identity theory. This version appears especially vulnerable because the notion of ‘aspects’ seems itself to be mind-dependent. A material entity has no outside-of-itself, from which it can be revealed as aspects of itself. A cup has a ‘back’ or a ‘front’ only for an observer. Consequently, mind versus matter cannot be merely a question of one aspect versus another but of having aspects versus not having aspects, of having a viewpoint versus being without a viewpoint.

So much for aspects. What, however, are we to make of an object – such as a brain – being the bearer of two properties as different as mentality and materiality? If property dualism seems attractive it is because it seems to address Princess Elizabeth’s objection: it permits the-brain-as-mind to engage causally with the world beyond itself – as an effect of external material causes and the cause of material effects – in virtue of mind and matter being on the same bus. Unfortunately, this raises the question of what precisely mind-as-property brings to the party. Any distinct input from the mental property seems to be dictated by its material partner, which ascends to mentality only in virtue of being a part of a particular brain engaged with other parts of that brain. The causal burden would seem to be carried entirely by the material properties. In other words, mind does nothing, brain does everything.

Wait a moment, you might say. Isn’t this problem generated by the assumption that the mental property is the junior partner, and that the material property is calling the shots? Indeed, it is. Nevertheless, this ranking seems justified. After all, mind is not found outside of higher parts of a brain generating certain kinds of activity. For this reason, it might seem reasonable to conclude that mind depends for its existence on a certain arrangement of physical stuff. The dependency does not go the other way: mental phenomena do not generate bits of matter. Besides, if the two properties had equal and independent powers, might there not be conflict between mental and material causation - unless there were some means of passing the baton, such that the outcome of the interaction between the brain and the extra-cranial world would be determined on some occasions by the mental property of the events occurring in it and on others by their physical properties? How this might happen is not clear and it would hardly be satisfactory if the outcome of the mental property of events were necessarily mental events while the outcome of the physical properties of events would necessarily be physical events. The material brain and the immaterial mind would be sealed in parallel realms.

Property dualism, as embraced by many neurophilosophers, does not therefore seem fundamentally different from materialism. Mind seems to have lost its status as the ontological equal of matter, applying equal traction to the order of things. Matter is everywhere – it seems to be the default mode of being. Mind, by contrast, is localised, existing only in minute stretches of the material world, courtesy of the behaviour of certain portions of matter. As such, it is not matter’s equal. What is more, its late emergence, such that some matter woke up to itself long after the beginning of the universe, seems to lack explanation.

Property Foreclosed

Demoting mind to the status of junior property, a parvenu beholden to physical nature, is an expensive way of dealing with the Princess’s objection to substance dualism – namely, that unextended, and consequently unlocalised, mind could not engage with the extended, localised body to influence its behaviour. And it is a particularly high price because it does not address the problem of localisation satisfactorily. If, after all, mind is non-localised, how can it arise from, or even be associated with, a particular location in a particular object – namely, a brain? Thoughts such as ‘my phone is missing’ or ‘Paris is the capital of France’ point to something untethered to a spatial location, such as that of a cluster of busy neurones (literally) inside my head. The intentionality of conscious contents makes them other than, and hence untethered to, the location of, any neural events with which they might be associated. This may seem to be obvious in the case of so-called ‘transitive’ mental contents that are about something other than themselves, such as my sight of a cup or my thought about Paris. It is, however, equally true of intransitive experiences such as pains and itches, that do not seem to point beyond themselves. The experiences are not co-located with the cerebral activity supposedly associated with them. After all, my pain is located in my foot, some way from any neural activity that identified as its material basis.

It would seem, therefore, that the Princess’s concern about the lack of location of mental contents, seemingly necessary for the mind’s interactions with the body and with the world beyond it, remains valid. Which is why the claim that the pain in my foot and my thought that my phone is missing are near neighbours in the intracranial darkness seems a profound misrepresentation. Mind as a property of entities that also have the property of being material is therefore no less problematic than mind as a substance parallel to matter as a substance. The contemporary mind-brain identity theory is as unsatisfactory as Cartesianism. While property dualism drifting towards materialism may seem more plausible to the philosophical community than full-fat Cartesian dualism, it does not deserve this free pass.

The relative attractiveness of property dualism may be explained by the sense that properties are less divorced from one another than are different substances However, it raises, and fails to address, the entirely reasonable question: “Properties of what?” And if the properties are deemed close enough to be housed in the same place, this will not do justice to the depth of the difference between matter and mind – between moving ions and the thought that Paris is the capital of France.

This may explain why some neurophilosophers turn to quantum physics to make matter more mind-like so that there will be no need to propose separate substances or even separate properties. This would not have satisfied Princess Elizabeth. She might even have agreed with the Gilbert Harman’s eloquent question: “[W]hy exactly is it the mission of philosophy to limp along after the science of its time?” (‘I am also of the opinion that materialism must be destroyed’ Environment and Planning D: Society and Space, volume 28, 2010). Better to acknowledge that materialism, dualism(s), idealism, and panpsychism don’t work, that ontology is a mess, and that neuro-ontology doesn’t tidy it up.

Raymond Tallis’s The Palgrave Companion to the Philosophy of Raymond Tallis edited by Robert Doede (Palgrave: Macmillan) is to be published this month.