A Smile at Waterloo Station
Quote:Let us return to that smile. It is supposed to be ‘stored’ in the changed state of excitability of a neural circuit resulting from my exposure to it. The state of the circuit is ‘a present propensity to react’, and when it does react, the memory is ‘activated’. That is to say, the memory is a present state of part of my nervous system: a physical state of a physical entity, namely my brain. This state has somehow to be about, or refer to, the smile. Yet it is difficult to understand how physical activity can be ‘about’ something other than itself. We encounter this difficulty in the case of the perception of something even actually present. The perceptual state is about the thing perceived. Outside of the brains of sentient beings, no other physical event has this ‘aboutness’. But understanding this aboutness presents an even greater challenge in the case of physical states that are supposed to correspond to memories: the states have to be about something that is no longer present – that no longer even exists. What’s more, memory in us humans is explicitly memory: it is not simply past experience acting upon us by reverberating in the present. That remembered smile is located by me in the past – indeed, in a past world, which, as John McCrone has put it, is, “a living network of understanding rather than a dormant warehouse of facts.”
Making present something that is past as something past, that is to say, absent, hardly looks like a job that a piece of matter could perform, even a complex electrochemical process in a piece of matter such as a brain. But we need to specify more clearly why not. Material objects are what they are, not what they have been, any more than they are what they will be. Thus a changed synaptic connexion is its present state; it is not also the causes of its present state. Nor is the connection ‘about’ that which caused its changed state or its increased propensity to fire in response to cues. Even less is it about those causes located at a temporal distance from its present state. A paper published in Science last year by Itzhak Fried claiming to solve the problem of memory actually underlines this point. The author found that the same neurons were active in the same way when an individual remembered a scene (actually from The Simpsons) as when they watched it.
So how did people ever imagine that a ‘cerebral deposit’ (to use Henri Bergson’s sardonic phrase) could be about that which caused its altered state? Isn’t it because they smuggled consciousness into their idea of the relationship between the altered synapse and that which caused the alteration, so that they could then imagine that the one could be ‘about’ the other? Once you allow that, then the present state of anything can be a sign of the past events that brought about its present state, and the past can be present. For example, a broken cup can signify to me (a conscious being when I last checked) the unfortunate event that resulted in its unhappy state.
Of course, smuggling in consciousness like this is inadmissible, because the synapses are supposed to supply the consciousness that reaches back in time to the causes of the synapses’ present states. And there is another, more profound reason why the cerebral deposit does not deliver what some neurophysiologists want it to, which goes right to the heart of the nature of the material world and the physicist’s account of its reality – something that this article has been circling round. I am referring to the mystery of tensed time; the mystery of an explicit past, future and present.
That remembered smile is located in the past, so my memory is aware that it reaches across time. In the mind-independent physical world, no event is intrinsically past, present or future: it becomes so only with reference to a conscious, indeed self-conscious, being, who provides the reference point – the now which makes some events past, others future, and yet others present. The temporal depth created by memories, which hold open the distance between that which is here and now and that which is no longer, is a product of consciousness, and is not to be found in the material world. As Einstein wrote in a moving letter at the end of his life, “People like me who believe in physics know that the distinction between past, present and future is only a stubbornly persistent illusion.” I assume that those who think of memory as a material state of a material object – as a cerebral deposit – also believe in physics – in which case they cannot believe that tensed time exists in the brain, or more specifically, in synapses. A material object such as the brain may have a history that results in its being altered, but the previous state, the fact of alteration, or the time interval between the two states, are not present in the altered state. A synapse, like a broken cup, does not contain its previous state, the event that resulted in its being changed, the fact that it has changed, the elapsed time, or anything else containing the sense of its ‘pastness’ which would be necessary if it were the very material of memory. How could someone ever come to believe it could?
Those who imagine that experiments with Aplysia cast light on memory betray the origin of the erroneous belief that memory is inscribed in matter. The belief is based on a slither from memory as you and I understand it, to learning; from learning to altered behaviour; from altered behaviour to altered properties of the organism; and viola! – the materialisation of memory! However, with Einstein’s help, we can see that sincere materialists must acknowledge that they have no explanation of memory. Instead of thinking that memories can be located in the brain (or even more outrageously, captured in a dish), they ought to hold, along with Bergson, that “memory [cannot] settle within matter” even though (alas), “materiality begets oblivion.” In short, they should take off their dull materialist blinkers and acknowledge the wonderful mystery of memory.
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'
- Bertrand Russell
- Bertrand Russell