Continued from my opening statement «
Steve has now posted his opening statement. I am duplicating it here for ease of reference.
The capabilities of the human mind are astounding, and its place of residence the brain, is the most complex thing we know of, and possibly in all of the universe. I believe this complexity functions to produce all the workings of the mind. I will attempt to explain how this is possible for a particular function of the mind, reasoning, and in doing so I am responding to the claim that reasoning requires the existence of the Christian God. That is a very specific claim, indeed it is both far more specific than I need, and at the same time too vague for me to be able to target specifics. To be honest, I’m not sure what the term “Christian God” means. Is it the God of the Orthodox Church, of Roman Catholics, of the Mormons or of the Anglicans? But no matter. I don’t need this specificity to address the claim. I intend to show that reasoning does not require that theism is true: no metaphysical entities are required at all, even if some metaphysical statements may be necessary.
To start, I want to address the apparent need to invoke any non-physical realms for an explanation of the reality of experience. This has a long history. Aristotle considered the world full of “universals” – standards that supposedly explained the consistency of experience. Redness, goodness, even “apple-ness” were all considered by many to have an actual existence of some kind. The universals I will come on to discuss are the ones considered relevant to reasoning.
Aristotelian metaphysics has influenced thought down the ages, and has been increasingly influenced by science. To illustrate the influence, I shall consider a colour universal: redness. Although the question of the sensation of redness is still a matter of discussion, we have an explanation as to why a particular object has this quality, in terms of the selective reflection and absorption of different wavelengths of light. The idea of a universal in this context is now largely redundant. We don’t talk about an “essence of red” that is part of the make-up of an object that appears red. However, some apparently universal “qualities” seem to have been more resistant to explanation in material terms. These include the moral attributes of good and evil, and the propositional attitudes – the realm of belief and intentionality that seems such a vital aspect of human reason, and the processes of logic.
Before discussing how these may be described in naturalistic terms, I would like to point out that in the past there has been a tendency to imbue excessive qualities to objects because of preconceptions about the nature of mind, of humanity, and of life in general. Vitalism is a useful illustration of this. Through most of recorded history the idea of life being some specific essence in and of itself, and it took the work of Wohler and the synthesis of “organic” compounds from clearly non-living constituents to start the process of breaking down this myth, and although there is a considerable amount left to learn about the functioning of cells, scientists are confident that this explanation will be entirely naturalistic. So life may well be purely physical at the level of the cell, but what about at larger scales? Is there anything emergent? Well, we find no requirement for any extra non-physical factors in the operation of organs in the body. The liver appears to need no supernatural aspect, and neither do the heart, kidneys, spleen, skin; and few theologists would claim that that such an aspect is present. Of course, one of those cellular organs is the brain.
Having seen the mistake of vitalism, are we also making a similar mistake of “mind-ism”? I think so. We know that minds are associated with brains, because of the causal connection between changes in brains and changes in minds. The effects of injury to the brain have shown that certain regions of the brain have different functions, such as processing visual information, interpreting language, planning, and so on. It isn’t just injury to the brain that reveals the physical basis of the brain’s functions; genetic differences can lead to changes in the capabilities of brains and minds. Dsylexia, a reduced capacity to deal with language can be inherited as can prosopagnosia, an inability to distinguish faces. Significant aspects of our ability to perceive and process even quite subtle information can be dependent on a few minor changes in DNA.
So it is clear that the brain contains structures that appear to be associated with the collection, storage and analysis of information. Are the types of structures present in the brain all that is required for such activities? It seems so. Decades of research into neural networks (digital simulations of the kind of activities and connections believed to operate in and between nerve cells in neural tissue) has revealed that even apparently relatively simple systems have great power. Networks have been built that can process many types of information, which can be interpreted as having different levels of meaning. Some networks can act in the manner of the visual cortex, analysing colour and intensity data. Other networks can be trained to distinguish faces: the same concept – interconnected nerve cells with feedback connections – works at many levels. Other networks can process language syntax. Even though an observer of the networks can impose different semantics as to what is going on, the operation of the networks is the same: simple transformations and switching of signals with feedback.
So although we don’t know the details, we have no doubt of the power of the brain as an incredibly sophisticated information processor. The question relevant to this debate is whether the workings of a physical brain are sufficient to explain the experiences of a mind in terms of reasoning.
I believe they are, and the reason is evolution. Nervous systems evolve to control bodies. They have been selected to process information from the senses and from their internal states in order to help a body survive and reproduce. It is clear that this selection can result in the development of systems that can recognise some truths and usefully process them to obtain correct conclusions, as in Nature mistakes frequently lead to death. Much of this processing is automatic: a fish will catch a fly above a pond correcting for the distortion of light without understanding refraction. A bat will change the tone of its echo-location as it approaches an insect without an understanding of sonar.
Two important (for this argument) stages in the evolution of the brain were the development of self-awareness, followed by language. As humans, we not only realise that we have experiences, but we attempt to describe these in symbolic form, and we have the experience of what it is like to manipulate those symbols. What needs explaining is why we have these feelings of intentionality and meaning. This is because we mentally model minds; this is a necessary part of how we live as an intelligent ape. We need to consider what other people may or may not do, or what they may be thinking. And the natural way to consider that is in terms of what their intent might be, and what may be significant to them. It is easy to see that with sufficient mental processing power, this modeling of others can take off, and allow the consideration of even more hypothetical and abstract situations, and while such consideration is taking place, the same “truth”, “meaning” and “intention” detection mechanisms would be available as when dealing with more concrete situations, as wondering if a neighbour is planning to steal food, or that tiger is going to attack.
The question is whether this mental processing implies what many say it does – that the propositional attributes have any reality, a reality which some imply requires the existence of a deity.
This takes us back to the matter of the mistaken invocation of universals. In the past, people have assigned meaning and intention very widely. For example, talk of the intention of the Sun and the Moon was common, sometimes resulting in the worship of those objects in order that they grant favours (such as renewing the cycle of seasons each year). We can still see the influence of the false assigning of meaning in the practice of astrology. This surely raises the question of when, even if, we should assume meaning and intentionality, indeed we should even question if it is present within our own brain-based minds. This may sound absurd, as surely we know our own minds. But there is no reason to believe that this must be true. We are all susceptible to illusion from our senses, and that is just as true for the “sense” of introspection. Memories are nowhere near as reliable as we tend to assume, and much of our second-by-second experience is extrapolated by the brain from surprisingly little information. I suggest that, without evidence to the contrary, all we have is the experience of truth and meaning when certain processing of information produces results that trigger (based on past experience and training of the mind) our mechanisms for detecting “truth” and “meaning” – just like we have the feeling of a colour when certain neuronal firing patterns occur.
So what are we left with? We have models of brain function that, even if incomplete, reveal the possibility that the forms of processing of information that we call reasoning can be performed by sufficiently complex neural networks. We can see reasons for the development of neural analogues of the propositional attributes based on evolution. We have no proof of this, but that it is conceivable within a purely naturalistic framework dispenses with the requirement for any god, let alone that of Christianity.
[I would like to thank cand. phil. Michael Bauer, Ludwig Maximilian University of Munich, who has provided resources and advice]