Wednesday, 15 February 2012

In Search of the Mind: An Introduction to the Hard Problem of Consciousness - Part one

[part 2 is here]
Introduction to the Mind-Body Problem
The Hard Problem of consciousness lies centrally to the Mind-Body Problem, concerning itself with the metaphysics (ontology) of mind. That is to ask ‘What is our understanding of the mind’s nature and what are the implications for its relationship with the physical world?’ This question traditionally leads to two distinct lines of thought; Dualism versus Materialism. 

To summarise the debate, we may do so as follows:    

Substance Dualism argues mind and body are different substances - they are “ontologically distinct” (Calef 2005). Whilst body and mind interact, mind is not reducible to brain. Materialists, recognising the problematic causal implications of dualism, propose mind is directly reducible to brain. This is Crick’s Astonishing Hypothesis (Crick, F. 1994).

Clearly, however, the mind appears radically different to the brain. The mind feels, has intentionality, phenomena, no location in space, no divisibility. Despite pitfalls, we can sympathise with dualism’s need for an explanation of how consciousness arises from non-consciousness molecules and neurons. Perhaps this is just too astonishing? For Chalmers it is, hence he coins the phrase ‘The Hard Problem’ to conceptualise what exactly the problem is (Chalmers 1995).

What is ‘The Hard Problem’?
The Hard Problem is how to explain subjective experience (qualia) in terms of physical processes and functions. How can we explain, as Nagel (1974) puts it, that “there is something that it is like to be [conscious]?” 

Chalmers argues consciousness can be understood in two distinct ways. 

The first consists of the easy problems; explaining the underlying functions of consciousness, such as perception and memory, which he collectively terms ‘awareness’ (‘Access Consciousness’ – Ned Block 1995). Whilst our knowledge of these problems is incomplete, the point is they can be solved within a reductionist framework – they are not concerned with explaining subjective experience. 

The Hard Problem arises as once we have explained these underlying functions; we are left with something extra – what Chalmers refers to as ‘consciousness’ (Block’s ‘phenomenality’). We are faced with Levine’s (1983) ‘Explanatory Gap’. 

Chalmers’ zombie attempts to illustrate this; we can conceive of a world in which humans are physically and functionally identical but without consciousness (zombies). We can explain ‘zombies’ in terms of the easy problems, perception etc, but we are left with something extra; subjective experience. Jack smart (1959) terms this the ‘Nomological Dangler.’ 

So does consciousness constitute a genuinely Hard Problem? For traditional scholars such as Descartes, Spinoza and Berkely, perhaps not since they do not take matter to be a basic assumption (Shear 1997) – although this presents them with the need for supernatural explanation - God. 

I will focus on giving a critical summary of the relevant arguments from more contemporary theories, such as property dualism, functionalism, neutral monism and materialism, encapsulated in ‘Consciousness explained…’ (Shear 1997) as well as other scholarly contributions and my own views. It can be broken down into five sections:

1) Those that reject the very existence of subjective experience/Hard Problem
2) Those that challenge the Hard Problem’s logic
3) Those who accept the Hard Problem’s logic but argue for a simple solution resting within the materialist paradigm
4) Those who argue the problem is harder than anticipated
5) Those who support the Hard Problem

I will argue in favour of the Hard Problem, proposing difficulties arise from “hard choices between cherished assumptions”, to borrow a phrase from Jeffrey Gray 2004. That’s not to say each assumption presents a ‘hard problem’ in itself, but that collectively these assumptions are components of what Chalmers terms the ‘Hard Problem’.

In fact, we have already come across our first two ‘cherished assumptions’: 

consciousness itself exists.’ 

consciousness is physical and thus can be explained reductively.’ 

1. What hard problem?
Dennett’s functionalism, rejects the very existence of the Hard Problem itself, asserting will be explained by solving the easy problems (Dennett 1991, 1996). His logic rests on ‘cherished assumption’ three;

‘the whole is no more than the sum of its parts’
In other words, once we have explained the processes and functions of the brain in terms of awareness, there is nothing additional left requiring explanation. 
Chalmers argues “…[consciousness] is not a problem about the performance of functions”. We can explain the functions of his mindless zombie thus are still left with conscious experience in humans untouched. 

We can challenge ‘cherished assumption’ three further. From a Gestalt perspective, the whole is more than the sum of its parts (see Johnson 2001). The overall premise is the appeal to the role of dynamical systems resulting in emergence that cannot be predicted by knowledge of the parts alone. Materialists may reject this kind of strong emergence appealing to a weaker form. Essentially, the question is ‘could Laplace’s Demon predict consciousness?’ (Laplace 1951).

Churchland (1995, 1996) agrees with Dennett in her eliminative approach, rejecting ‘cherished assumption’ number one; qualia’s existence. She attributes it to folk psychology, which will be rejected as science progresses as with the case of ‘phlogiston’. The disanalogy here is that the concept of phlogiston is not directly available to us as a necessity. Qualia on the other hand are directly experienced and therefore, as Descartes (1644) recognises, cannot be denied – “cogito ergo sum.”

2. Mary’s knowledge and a god that can’t conceive zombies
The Hard Problem’s logic has been widely challenged (Kirk 2011). I will limit myself to two important problems:

The Kripkean perspective (Kripke 1972) can be used to challenge Jackson’s Knowledge argument (see Jackson 1986). 

Jackson imagines a scientist, Mary, who knows everything there is to know about colour and its processing in the human mind, however, she, herself can only see in black and white. If one day, Mary regains her colour vision and experiences colour 'the redness of a rose', surely, she will have gained knowledge about colour in the form of her new subjective experience?

This is problematic for materialists as, if experience can be explained physically, Mary should not gain any new information from her new found colour vision, since she already knew everything physically there was to know about colour.

Jackson's argument rests on the assumption that if physicalism is true, we can deduce the complete truth about Mary’s colour vision a priori from the complete physical truth.

However, we can apply Kripke’s example of ‘water as H2O’ being metaphysically necessary a posteriori, to argue that the “psychophysical conditional is metaphysically necessary but not a priori.” This explains why, within a physicalist paradigm, we wouldn’t expect Mary to ‘know’ a priori the qualia of colour. (Alter 2005.) 

Papineau (2003) and Dennett (1991) challenge the ‘conceivability argument’. This poses a threat to the Hard Problem, which rests on the assumptions a) zombies are conceivable and b) conceivability entails possibility. Both assumptions have been challenged; the former by Dennett and Cottrell 1999, arguing that Chalmers underestimates the task of what imagining a zombie would entail, and the latter by Papineau, arguing “even God could not make a zombie”, - consciousness arises from the brain as a result of necessity. 

Although beyond the scope of this blog, it is important to recognise the debate is on going. Chalmers (2010) responds with his ‘framework of two-dimensional semantics’, arguing this forces the materialist to reject reductionism or assume 'Russellian Monism'. 

The debate remains open but as Gray states, “It is a stark illustration of our lack of understanding of the functions of consciousness that no one is at present sure whether zombies could or could not exist in reality.” Our fourth ‘cherished assumption’ is therefore:

 ‘the imaginable existence of zombies’

In part two, we examine the functionalist approach further, consider identity and emergent theories, what makes the Hard Problem so hard and how we might go about tackling it.
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  1. Nice post. I have often heard people explain zombie problems that start with the premise, "You can imagine...." and I reply "No, I can't imagine that, and neither can you." The conversation gets pretty awkward from there.

    In particular, I don't think you can imagine getting chased by a zombie without imagining that the zombie wants to catch you. That the zombie is chasing you entails a mental state. If the zombie is not chasing you, the events go something like this: You are running down the street, with a zombie close behind, but then you turn down an ally, and the zombie keeps running down the street.

    By the way, I linked to this post, albeit subtly, in my new post.

  2. Thanks Eric

    I think the zombie argument is an interesting one, unfortunately there's a huge debate about conceivability and possibility that surrounds it and I get a bit lost! :-) see here

    With regards to your example, I would argue you can still explain the zombie's apparent 'intentions' on a functionalist level, without appealing to any kind of subjective consciousness.

    That is, just as a robot can display apparent intentions (imagine a robot chasing you), it does not mean the robot, (or zombie) has any kind of conscious awareness or subjective experience of it's behaviour. Another example might be a computer playing chess - it has the apparent intention of wanting to beat you but no actual experience or consciousness.

    Obviously, there is a big disanalogy between computers and minds but I don't think that is problematic for the zombie argument?

    For me, the problem is not whether you can conceive of zombies behaving in exactly the same way without consciousness. This is conceivable, based on the robot example I gave. Although it may well be impossible to ever have a computer sophisticated enough to perfectly immitate a human,the point is I don't think adding subjective consciousness is logically necessary in order for this to be achieved. Hence with the zombies, we don't need to add consciousness to explain their behaviour.

    The real problem to me is that we can't conceive of a zombie WITH THE SAME ANATOMY AND COMPLEX NERVOUS SYSTEM (AND INTERACTION WITH ENVIRONMENT), without consciousness. That is, the problem lies outside the debate of whether consciousness is necessary for a convincing human. The problem is whether it is conceivable that consciousness would not exist in an otherwise identical zombie. Could god create a zombie or would a zombie necessarily have consciousness?

  3. I think we can intellectualize the example and talk about it in the manner you describe... but I think that if you were being chased by the robot, then, to you at that moment, the robot wants to catch you. It is conscious of you, it has a goal, it perceives, etc. Heck, if the robot was half-crushed, the effect might even be stronger! And by "if you were being chased by a robot", I also mean, "if you imagine it with sufficient seriousness."

    The identical nervous system issue does add an additional layer of seeming impossibility. The argument that the zombie could be exactly the same, and yet completely different, is an odd one. I'm just willing to put up a fight either way.

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