The scientific nature of the mind-body problem

Pedro Fonseca


I – The present mind-body problem

1. Nowadays we stumble across a conceptual difficulty in explaining everything that is related with consciousness. We do not understand why it has appeared in natural evolution and how it is caused by merely physical entities. We do not understand why it was (and is) necessary to improve animal behaviour because it adds nothing to the behaviour of any physical being (the behaviour would be exactly the same if it only possessed physical properties – if it was an automaton or a zombie). And we do not understand how they are possible because we do normally admit (upon scientific reflection) that what there is, the fabric of the world, is just a set of elementary physical particles (EPP), that makes up everything else. The logical consequence of this ontological commitment is that non-elementary entities are just representations, tools, introduced in explanations. They are certainly useful to us – given our very limited powers of calculation and measurement – but are nevertheless mere images of what in reality is just an incommensurable jumble of EPP.  Through this perspective, it seems impossible to ascribe any role to consciousness, or to conjecture how it arises from matter. In reality, everything would be simpler if we did not exist (phenomenologically).

2. But can or should we change the assumption that EPP are sufficient to have a complete description of reality? I think that we should because I believe that, as long as we do not change this assumption, we will not be able to explain consciousness. For suppose that the behaviour of any physical entity can indeed be completely predicted, even if only in principle, employing exclusively a complete description of the physical properties of EPP.[1]  One of the consequences is that non-EPP cannot possess causal powers, and, following Occam’s principle, they should not, therefore, exist. The reason for this is simple: the introduction of entities that do not have causal relations with other entities can only be made arbitrarily (since the attribution, non-attribution or misattribution of ‘green’ to a physical system has no consequences, how should we choose between them?). So, we may think that, following the opposite direction, i.e. considering as evidence the causal properties of the mind, and proceeding to the appropriate adjustments to the actual assumptions, theories or interpretations of science, we should head, in a better way, to a new scientific paradigm, simultaneously less mysterious and more believable, one which we might, luckily, achieve. We are therefore assuming that our best scientific theories should be consistent with a possible solution to the mind-body problem. In this way, not only philosophical discussions, should highly rely on the concepts of physics, but the scientific theories should also try to be consistent with every area of what we can experience.

3. The difficulty in pursuing this research avenue (besides the fact that almost no one is following it) is that any description, which attributes causal powers to entities that are not EPP, seems to enter the domain of superstition or irrationality. There are at least two problems regarding the view that non-EPP entities may have causal powers. First, it might be argued that a non-EPP entity with causal powers is a contradiction in terms. But it can also be argued that the problem of explaining consciousness would not be helped by the addition of non-EPP entities with causal properties – consciousness would remain as mysterious as ever. Let’s start by the first argument. In general it is simply assumed that almost every property of a composite is determined by the properties of its (elementary) parts. So it is said that two objects indistinguishable at the level of their parts could not have different (intrinsic) properties. This claim is made stronger if we consider a 4-dimensional region of space-time so that the EPP will include, not only a particular moment of the world, but a part (or the all) of its history.

But imagine, by the contrary, that the parts of an object would be insufficient, somehow, to describe its causal powers. This is what happens in (at least) some quantum events. We have a description of the elementary parts of an object (like a radioactive atom) or even of an elementary object (like a photon). But this description involves a substantial degree of uncertainty. We know that an atom has a certain probability of decaying, but will it decay? Neither the theory, nor further observations seem able to answer that question. Some people have argued that reality ceases to be objective at the quantum level, that perhaps the future is not completely determined by the past and so on. This is speculative, but it is sufficient to show not only the conceivability but the actual possibility of having two exactly alike atoms, even in twin universes, and seeing one of them decaying while the other does not decay.

Let’s consider this sufficient to assert that exactly the same composites may behave in different ways (not only as a logical but also as a real possibility). Would this help solving the problem of consciousness? We would still have to secure two different caveats. First , if consciousness has some causal powers, then it must have not only the opportunity to show them, but it must actually show them. What we see in quantum systems like electrons, etc, is just random behaviour. This is not what we would expect to happen in the brain. If we ever find that there are quantum random mechanisms in the brain we should expect to find that they, contrary to the current predictions of our current physical theories, do not operate randomly – consciousness should show itself in the world in an unambiguous manner, it should have strong empirical consequences. The second caveat is that we must separate the problem of finding a place or function for consciousness, or choice, in the natural world, from the problem of providing a reductive explanation of consciousness. Even if we were to discover that the person is behaving in a way not explainable by physical theory we could still believe (perhaps even more!) that everything we were living was just a dream or an illusion placed in us by some Cartesian demon. The possibility that everyone around us is nothing but a zombie is as real as the possibility that the world is nothing but an illusion. These are sceptical doubts that are beyond the frontiers of our knowledge, and I cannot imagine how anyone (or even a being like God) could escape these doubts unless by simple acceptance or faith.

4. In spite – or perhaps because – of these changes inside the physical paradigm, almost all solutions to the mind-body problem have searched for a conceptual disentanglement that do not contemplate physics. The solutions were searched and found in the lines of interpreting current physics as if it were Newtonian physics: idealism, parallelism or physicalism are just interpretations of Newtonian physics. But these interpretations cannot avoid the problem that stems from Newtonian physical theory: consciousness has no place or function in nature.[2]

The actual incapacity of achieving a consensual explanation by any of these solutions corroborates our hypothesis according to which, without taking into account some major step back from the deterministic worldview endorsed to us by Newtonian physics, the problem is simply intractable.

5. Today we can witness some efforts to take advantage of certain assumptions in contemporary physics that may reveal to make the mind-body problem tractable. Penrose and Hameroff have been part of the few that have strived to accommodate quantum physics and neurology (assuming small arrangements in both) with the existence of the mind. In a more radical effort, the empirical investigations leaded (which do not address directly the problem of the mind) by Prigogine seem to suggest that the impossibility of predicting the behaviour of unstable systems is not due to a lack of information but to the intrinsic nature of the system. If this is true, a certain solution to the mind-body problem would be possible: since the elementary description is not sufficient to completely predict the behaviour of the system, other non-elementary (physical) properties might be not causally irrelevant – a solution that could, at least in part, suit a Bergsonian solution to the mind-body problem.[3]

One of the main differences between Penrose and Prigogine’s solution is that the first depends in an essential way of the not well-understood quantum effect of superposition. In the second, it will perhaps be possible to imagine a conscious system (with physical causation) based in an unstable system (with no quantum superposition states). Another line of investigation is to connect Leibniz parallelism with Everett’s interpretation of quantum mechanics. This project, however, presents several remarkable difficulties, the main one is the repugnant but apparently unavoidable conclusion that almost everyone we know are nothing but automatons (although we would not be able to distinguish between automatons and real persons).

II - Argument


To clarify the argument let’s present it in a more schematic way. Basically it consists of three premises and two syllogisms.



The first, “A”, is a definition of what I call the classical mind-body problem, of which a special case is treated by Kant, Leibniz, etc, and can also be found to have an important weight in arguments provided by Putnam, Papineau, Dennett, etc. I suppose “B” and “C” are accepted facts.



The mind-body problem can be understood as a consequence from the thesis that minds cannot have causal (physical) powers due to the nature of the world (and not by reflection on inner experiences, or metaphysical assumptions). It arises in every complex system in which behaviour is predictable through a complete description of its elementary parts. That is, it is generated in every system of entities arranged in such a way that, if composite entities exist, their behaviour is considered to be determined solely by the behaviour of the elementary parts that constitute them and their surrounding. It is unimportant if these elementary particles are considered physical (whatever this means) or not: a simple epistemological consideration will suffice to show that (from the previous assumption) the relation between parts and composites is sufficient to preclude any non-arbitrary assignment (from an non-pragmatic point of view) of causal efficacy to composites of any degree of complexity (even those formed only by two elementary particles).[4]



Newtonian dynamics was thought to provide such a system of the world. Since every particle behaviour and concatenation of particles was thought to be predictable (in principle) with absolute certainty. (It is very difficult to say if Newtonian dynamics did really said this, especially because it is still impossible to solve equations were involved in predicting the behaviour of several particles at a time: the classical example is the three-body problem.)



Quantum mechanics does not provide such a world-view. The equations do not allow us to predict accurate observations in most cases. This is all we need. Nevertheless it may be unsatisfying not to get a world-view corresponding to indeterministic particle behaviour. Several interpretations are possible but we must remember they are only interpretations, in the sense that they have a relevant and non-eliminable level of arbitrariness. However, since this may provide a more intuitive perspective to our argument, we may say, for instance, that the equations do not describe what we see but only the mechanisms that lead to possible observations. We could reframe this by saying that quantum mechanics equations describe possibilities, or the state of possible affairs. These possibilities have, nevertheless our intuitions about matter, a causal role. If we redefine our intuitions on matter such as to include the causal efficacy of possibilities we will end up with a conception of matter that does not operate at a mechanical level. Most important for our discussions, if possibilities define what happen they can never yield exact observational results because the mathematical result consists in a set of possibilities, from which only through actual experiment, some emerge as real. Observation, not theory, decides between possibilities, and this means they are intrinsically unpredictable. Anyway, we can use other interpretations of quantum mechanics, including Everett’s, for us the result is the same: no predictability.




The situation in the seventeenth century could be defined as:



B à A

\ A




With the evolution of predictive mathematical models it was paradoxically found that predictions have a maximum degree of accuracy. Newtonian dynamics was replaced but quantum mechanics mathematical models do not support A. It remains to be seen if they imply ~A.


correct argument



\ ??


but sometimes


B à A

\ A (fallacy)




III - Relevance


I don’t think the main argument can be easily considered wrong. It’s too simple for that, and its premises are almost all trivial. The main criticism (which may turn out to be true, but only to some extent) is that it is irrelevant. I can thing of at least two reasons may be given for this. What I’ll call a weak and a strong one.


Weak: just to say that it does not solve the ‘hard problem’ of consciousness (the ‘zombie problem’) and a host of related problems. For instance, problems related to the search of the neural correlates of consciousness. I would like to say that this is not a criticism, just a clarification, but it nevertheless shows that it is important to distinguish between general sceptical problems and problems amenable to scientific discourse.. I am not very sure that, after we solve the scientific problems, (mind-body problem included), many things remain to be solved. Part of my conviction resides in the fact that at least some of these problems consist in perennial philosophical problems (that does not happen in what we called the mind-body problem). Finding a solution to these kind of questions, like knowing if the world is real, or if we were created just five minutes ago with all memories implanted inside, or if the sun will rise tomorrow, etc, seem therefore much more improbable. Perhaps we will find that there is no answer to these problems except simple allegiance.


Strong: The scary part is that the mind-body problem can perhaps be re-established at another level of reality. For instance, at the molecular or biological level. My answer here is weaker than the former: if at all possible the re-establishment of the mind-body problem at a higher level cannot be derived from quantum mechanics, the equations do not tell us when particles begin to behave like good disciplined corpuscles. To have good reasons to believe in such orderly behaviour from a certain level up in relevant organisms (like brains) we would need evidence that cannot be derived from the general outlook that quantum mechanics gives us of the way the world works. That is, we would need to show, by other kind of empirical evidence, that these relevant organisms, or all of its parts at a single level, behave in a predictable way. For instance, if we would find that all molecules behave in a predictable way than it would seem that brains would also have to be considered as behaving predictably. In any case the resulting world-view would be rather strange, having a closure of chemistry or biology but considering at the same time physics to be incomplete. Even if this criticism turns out to be sound, it does demand quite a revolution in our current picture of the world.



[1] I take this to be roughly equivalent to the thesis of the causal closure of the physical. And the fact that quantum mechanics does not allow, in some hidden-variables interpretations, a complete description of elementary particles does not affect our argument since, besides EPP (and with the exception, according with the Copenhagen Interpretation, of the mysterious interactions with the (conscious) device that makes the observation) no other entities are considered relevant to make predictions.

[2] Notice that, when physics first appeared, it was understood as ‘natural philosophy’. It should deal with a part of the world (a very delimited part of the world) while the rest of philosophy would take care of the rest. But nowadays we understand much better that the claims of science are not only valid for the skies or for inanimate objects. The problem is that, in extending the claims of physics in such a way as to encompass the behaviour on all living beings, of every conscious experience, we must also demand that physics must be judged on the solution of problems that it never even tried to address before (like the problem of consciousness). We should demand that physics, now that it tries to explain what fundaments our phenomenal experience, must itself change to accommodate the phenomenal experience which it tries to have a hold on explaining. This is necessary, for the evolution of science.

[3] “Life [or consciousness], therefore, must be something which avails itself of a certain elasticity in matter – slight in amount as this probably is – and turns it to the profit of liberty by stealing into whatever infinitesimal fraction of indetermination that inert matter may present.” H. Bergson, “Life and Consciousness” p.18.

[4] There is also a relation here, not yet very clear to the problem of individuation, but we will skip that part here.