By Paul Almond, 8 October 2004
'Order, unity, and continuity are human inventions, just as truly as catalogues and encyclopedias.'|
- Bertrand Russell (1872-1970)
Most people believe in some sort of continuity of existence, or 'continuity of self'. This is the idea that the same 'you' existed yesterday, exists now and will hopefully exist tomorrow.
This is significant to life extension ideas. A likely reason for attempting to extend life is to preserve continuity of self. Many would demand that any proposed life extension method achieve this to be worthwhile, arguing that it is otherwise a failure.
Arguments are made against some life extension technologies, based on claimed loss of continuity of self, and they propose that the person who is alive after an apparently successful process is not the person who underwent it, who gained nothing. For example, some people think that some form of continuous brain functioning is needed for continuity of self and that the absence of this during cryonic suspension would mean that the person who was revived was not the original person. Others argue that cryonics must ultimately fail because the extreme repairs needed to revive a cryonically preserved brain would mean that it was not 'the same brain' afterwards. As another example, mind uploading, a more extreme process, which would involve storing a description of a brain and then transferring that description into another system, faces an objection that the uploaded person is a duplicate and the original person is dead.
This article will not refute such arguments individually. Instead, I shall examine the idea of continuity of self generally. There are reasons for thinking that it is a fallacy and the implications of this for life extension will be discussed.
Strong and weak continuity
We will start by looking at what 'continuity' means.
I define two sorts of continuity: strong continuity and weak continuity. When people talk about continuity of self they usually mean strong continuity; however, various forms of weak continuity feature in everyday life. Such ideas are so pervasive that we rarely notice our use of them.
Strong continuity is the idea that a thing has an existence of some duration, during which its identity is preserved in some absolute way. Most people think they have this sort of strong continuity of self. The main characteristic of strong continuity is its non-negotiability. If two people disagree about whether or not a thing has ceased to exist then one of them is wrong: there is a real sense in which the thing can be said to exist or not exist. If something has strong continuity it makes sense to discuss where its identity is at various times and whether its identity is restricted to one place or can be in many places at once and correct answers can be obtained to these questions.
We do not restrict continuity to ourselves. We use the idea of weak continuity for other things. As with strong continuity, weak continuity is the idea that a thing exists and can be treated as being the same entity for some period of time, but it does not go as far. Weak continuity gives a thing an identity for convenience and it is negotiable; for example, two people could disagree on whether or not something had ceased to exist, where it was or whether or not there was more than one of it and it would be meaningless to say that one was more right than the other. If two people disagree over a matter of weak continuity the most that can be said is that one person's view is particularly convenient.
As an example of weak continuity, let us consider a car. After some maintenance work is it the same car? Does the amount of maintenance work matter? If we replaced a headlight bulb would it be the same car? What about an engine replacement? What if we kept making repairs, so that over time every part had been replaced? Would it still be the same car? If not, did the original car cease to exist at some point or did it gradually lose its identity? It should be apparent that these questions have no firm answers and that the way we assign an identity to the car is based on convenience. If someone announced that he/she had proved that cars which have had all of their parts replaced are actually new cars we should be at best sceptical and may even think it an absurd question to consider: there can be no such proofs of 'correct' weak continuity because it is negotiable, based on subjective opinions or circumstances which can make some views of identity more convenient than others.
The common view of human continuity of self is one of strong continuity. This seems to fit the widespread belief that we have 'souls', though if this were established we should want to know what gives a soul this strong continuity. Some people would suggest that our continuity relates to the specific matter from which we are made, but this does not deal with the issue of whether or not we would continue to exist if our matter were rearranged into a different form or, more complicated, if all of the particles in our bodies were numbered before we were dismantled and put back together with each piece in its right place, like London Bridge when it was moved to Arizona. Scenarios like this deserve consideration and are explored in Peter Unger's book Identity Consciousness and Value .
Some argue that we should not be concerned about the specific matter that makes us up, as matter is gradually lost and replaced in human bodies anyway: being overly possessive of our atoms may not make much sense. These people argue that 'you' are the pattern in your matter, rather than the matter itself, and that you would continue to exist if that pattern were realised in some other matter; for example, if a duplicate of you were created and the original destroyed. Others go further and argue that any system that has a pattern that is computationally equivalent to your pattern, even if that system works differently to your brain, would still be you and that if such a system were made and your original body ceased to exist you would still be alive. We need to examine these ideas carefully: the extreme nature of such proposals, and their concentration on information rather than matter, could lead us to conclude that their advocates reject strong continuity of self. This is not necessarily the case! If anyone held these views as I described them he/she would still be holding to a concept of strong continuity of self and merely arguing that preservation of information, rather than the specific matter in a person's body, is adequate to maintain strong continuity of self. Anyone who, in a discussion of this nature, advocates a process and says, while meaning it and choosing his words carefully, 'If this process were done I would still survive as a person,' or, 'If this process were done then the result would still be me,' can be reasonably presumed, I suggest, to be accepting the idea of strong continuity of self until he/she provides further qualification.
Why do we want to survive?
Continuity of self appears to be important when it comes to not wanting to die, so we should not discuss this issue without looking at why we have such a preference for survival.
The motivation to survive is often called the survival instinct, but what do we mean by the term instinct? In Design for a Life, Patrick Bateson and Paul Martin  indicate some of the difficulties in defining it, also describing the common understanding of instinct, stating:
'Instinct is also regarded by some as the basis from which all behaviour is created. In common usage instinct has various other connotations: they include "biological" (as opposed to "psychological"), "hard-wired", "congenital", "endogenous", "natural", "inborn", "constitutional", "genetically determined" or simply "genetic". These terms all carry similar theoretical connotations about the nature of behaviour. Instinctive behaviour patterns are, so it is said, inherited, internally motivated and adaptive.'
We have this idea that instincts are genetically hard-wired. It seems to me that the term instinct is used, even in this sense, to describe two different things.
Some instincts seem to deal with hard-wired behaviour and dictate a specific behavioural pattern. I shall call these behavioural instincts.
Other things that we may think of as instincts do not seem to dictate a specific sort of behaviour, but seem to dictate a specific goal to the animal, whose planning capabilities can determine how best to achieve it. Feelings of hunger would seem to take this form: we seem to have an instinctive need for nutrition, but the instinct does not appear to specify how we obtain it. Instead, it seems to create a desire for nutrition and the brain's planning capabilities can be left to decide how to satisfy it. I shall call these types of instincts goal instincts. Not all goal instincts need to create motivations to obtain things: some will cause us to avoid certain experiences that may be damaging to us.
The existence of multiple goal instincts could appear to cause conflict: behaviour that is ideal for satisfying one goal instinct could be unsuitable for satisfying another one. This is resolved though if, instead of regarding each goal instinct as setting a specific goal which has to be satisfied, we regard it as contributing to an overall evaluation of an individual's situation.
We can see how this might work by considering chess playing programs. These use evaluation functions [3, 4]. A chess evaluation function is a computation that returns a score indicating how desirable a chess position appears to be and is used to help the program to select moves. The evaluation function examines various characteristics that are thought to be indications of desirability or undesirability in a position and gives the program an indication of how favourable a particular position is to it - that is to say, what its chances are of winning from such a position. The important point is that this is all that the evaluation function does. It does not suggest suitable moves: these are determined by a planning system that uses a tree search to explore possible moves that could be made, possible replies to these moves, possible replies to the replies and so on. A tree search like this cannot proceed forever and eventually the evaluation function is used to determine how desirable some hypothetical future position in the game is. Using the evaluation function in this way - to evaluate the desirability of possible future positions - allows the desirability of possible moves that could be made now to be estimated and this allows a move to be chosen.
The chess analogy provides a model for goal instincts, in which each is part of an evaluation function used to indicate the desirability of any real or hypothetical situation in which the organism is. Other systems in the organism perform planning and they explore the consequences of possible actions that could be performed. The evaluation function determines the desirability of hypothetical future situations that could arise as a result of performing various actions, and so indicates the actions that seem best. Am I suggesting that humans are little more than chess computers? No - I am merely using the idea of chess computers as a simplification of how instincts may relate to the planning of actions.
Goal instincts are limited by their lack of abstraction. DNA can construct a brain containing simple goal instincts, but because the brain does not contain much of a representation of the world, these goal instincts can specify the desirability of various situations with reference only to simple experiences via the senses. A goal instinct could, for example, specify the desirability of certain taste sensations or the undesirability of experiencing extreme temperatures. An organism functioning in this way would be simpler than us. Even if capable of complex planning, it would only be able to assess the benefits of an action in terms of its effect on the results of a very simple evaluation function. This would make the equivalent of the evaluation function less effective than it might be because, even when the organism's brain has acquired a more sophisticated representation of reality, its evaluation function is not expressed in terms of any of this, but only in terms of simple perceptions.
We can now consider how more complex motivations could arise. After many experiences the brain may notice relationships between characteristics of situations that have occurred and the values returned by its evaluation function later and, importantly, these situations need not be expressed at the simplistic level of sensory inputs: they could be expressed using whatever sophistication is afforded by the brain's understanding of the world. These characteristics could then be incorporated into the evaluation function, giving it more sophisticated evaluation methods that use all the sophistication available in its view of the world. Such characteristics, which have emerged in this way, would control the system's planning in the same way as goal instincts, but a reasonable case could be made for saying that they would not really be goal instincts, as they would not be genetically hard-wired into the system. I shall call them emergent goals.
Emergent goals then, while not goal instincts, are closely related to them. Like goal instincts, they are part of the evaluation function and are created to serve the goal instincts. They use the context provided by a world-view to express goal instincts in a more abstract way that allows them to evaluate the desirability of a situation in terms of how the goal instincts are likely to evaluate the situation that follows from it later. The process need not stop here, with emergent goals being added to serve the goal instincts: as more abstraction becomes available, more abstract emergent goals may be created to serve not only goal instincts, but also previously created emergent goals.
We can now relate this to 'the survival instinct'. Is it really an instinct at all?
Humans appear to have patterns of behaviour that facilitate survival. We could call these 'survival instincts', but this would be almost trivial: we can expect any instinct to be involved, ultimately, in enabling procreation or survival. It is not what most people mean when they use the term 'the survival instinct'. What people really mean, when they say this, is our desire not to die.
Although specific behaviour patterns may exist that satisfy it, the desire not to die does not require any rigid pattern of behaviour: humans will resort to all kinds of behaviour to avoid dying, from hiding in caves from predators to steering fighter planes away from missiles. What we call 'the survival instinct' would have to be either a goal instinct or an emergent goal. That is to say, rather than being a pattern of hard-wired behaviour, it would have to be part of the analogue of the evaluation function in humans.
For 'the survival instinct' to be a goal instinct it would have to be hard-wired into brains by DNA. This would only be possible if the brain had a sufficiently sophisticated world-view to give context to such a motivation. Is this likely? For it to be possible to express the idea that dying is undesirable in a brain, that brain would need to contain some concept of what 'dying' means. It relates to the idea of what it means to 'stay alive' and neither 'dying' nor 'staying alive' are simple concepts.
We could attempt to define 'death' in a simple way as 'extreme damage to an organism'. Such a definition is incomplete, but to provide a context for avoiding death, even defined in this way, any world-view providing an adequate context would need to incorporate ideas of what 'an organism' is and what constitutes 'damage' to it. Our idea of 'death' is somewhat more abstract than this and seems to involve the idea of damage to an organism that is severe enough to prevent functioning. Even that is not enough to properly define what we call 'death', but there is already a lot of abstraction: not only do we need an idea of what the organism is and what constitutes damage, but we now also need a concept of what constitutes 'functioning' for the organism.
This problem of abstraction and context is unavoidable for 'the survival instinct' and can be illustrated by another, more extreme example. How seriously would we take the idea that humans have a specific 'complete my tax return on time' instinct? Even overlooking the lack of evidence, the idea of a 'tax return instinct' would seem inherently ridiculous to us because we know that humans are not born with a view of the world that is sophisticated enough to have any concept of tax returns, making it impossible to have any motivation towards completing them on time. Brains do not seem to be hard-wired with this amount of sophistication.
For the same reason, it is unlikely that 'the survival instinct' is a goal instinct because of the abstraction in the concept of 'survival'. What we call 'the survival instinct' needs a sophisticated view of reality to provide it with a context in which to be expressed. The 'survival instinct' is emergent, rather than being hard-wired, and we should classify it as an emergent goal. If we think that instincts need to be genetically hard-wired in some way then 'the survival instinct' is not an instinct at all and would be better described using another term, such as 'the survival motivation'. Of course, semantics is a matter of choice and we could continue to use the term 'survival instinct', but we should accept that doing this implies a definition of 'instinct' that does not require genetic hard-wiring.
Why satisfy our evaluation function?
Why should we want to meet the requirements of our equivalent of an evaluation function? The answer is simple: we do not need a philosophical reason. Our brains are built to satisfy our evaluation function and it is this that defines what we want. Asking a person why he/she does not step beyond the constraints of his/her evaluation function and want something else is as meaningless as asking a cruise missile why it does not 'choose' to abort its mission and go on a vacation. It is not in a cruise missile's nature, or ours, to make certain 'choices' and if anyone made an artificially intelligent cruise missile that could have a conversation, asking it to philosophically justify crashing into buildings would be futile: its designers would have made sure that it simply had an imperative to do this sort of thing.
We could ask the more meaningful question of why it is that the basic goal instincts in humans, combined with different experiences, produce the survival motivation. Humans have different preferences. The reason that the survival motivation is nearly universal is not that it has any philosophical justification. Darwinian evolution has tended to create DNA that makes brains with a particular structure and particular goal instincts that lead to the emergence of the survival motivation when those brains interact with the world. There is nothing random about this: a brain with an inbuilt tendency to cause the emergence of the survival motivation as part of its way of evaluating situations has a tendency to facilitate the survival, and ultimately the reproduction, of the organism that contains the brain and Darwinian evolution tends to produce machines that are good at reproducing themselves.
How does this relate to continuity of self?
These arguments may seem strange in an article about continuity of self, so I shall now relate them to what we are discussing.
The arguments are notable in that they do not contain any philosophy about continuity of self. That may seem strange as a way of declaring them relevant to a discussion about continuity of self, but I think it is extremely important! Many use the idea of wanting to preserve continuity of self as an underlying philosophy behind our survival motivation, yet the arguments which have just been given suggest that our survival behaviour is not based on any firm philosophy, but is simply a feature that emerges in our brain due to its usefulness in propagating genes.
If we accept the idea of continuity of self this should worry us. We may construct all kinds of philosophical arguments to justify avoiding something that could kill us, and to explain why it would kill us, but the brain's behaviour when it causes us to act like this does not seem to require any such explanation.
Some readers may argue against the position that I have taken about how our instincts are loosely analogous to a chess evaluation function, to which abstracted motivations are added, but the problem would remain even if some reasonable, alternative model were chosen. Any attempt to explain our apparent 'survival instinct' would have to deal with the abstract nature of the concept of 'survival' and the fact that all of this hardware in our skulls was generated by a process that selected it to propagate genetic patterns and this would seem to require any model to feature the idea that our survival motivation is emergent, rather than being hard-wired, and that the ultimate cause of such motivation is better explained by Darwin than by philosophising about continuity of self.
If we had just moved out of the way of a truck that were about to hit us, we could try to provide some firm justification, based on continuity of self, for our actions, but what if we are simply trying to find a justification for our actions after the fact? What if there is no such justification, but instead we are simply built to do it?
These questions lead to a further, inescapable and possibly unpleasant question: what if strong continuity of self does not exist?
Does continuity of self exist?
For us to introduce a concept into our view of reality, the world should make more sense with that concept than without it. As an example, one of the reasons for accepting Newton's law of gravitation was that when it was assumed to be true the movement of the planets appeared 'correct' - it was in accordance with our adopted view of reality (with some exceptions that we will not go into here), but if we imagined gravity not to be operating then the motion of the planets would not be in accordance with our expectations.
Strong continuity of self is accepted by many people because they feel that it is needed to make sense of how things seem to us, but to be consistent we should insist that it meets the same standards that we would apply to a law of gravity or any other scientific idea.
Let us try a thought experiment:
We will assume that strong continuity of self exists and that you have it. Assume now that, through some terrible reorganisation of reality, this continuity 'failed' last night, although the memories in your brain are exactly like the memories that existed in it before this failure and your personality was not altered by the failure - apart from it being someone else's personality now, of course! Let us assume that no other traumatic event accompanied this failure: all that happened was failure of 'continuity of self'.
How would you know that this had happened? You would have memories of a past life, before the failure of continuity, but there would be nothing to indicate that these memories were not your own and that strong continuity had been lost. If a failure of continuity had happened in the past there need be nothing to tell you that it had happened at all: things could seem to you just as they are now and for every situation in which you can imagine having existed with an unbroken continuity of self through your life it should be possible to imagine a situation in which the continuity has failed without your knowledge.
Let us now imagine that these failures become more frequent, so that you have a failure of strong continuity every few seconds. This may make a mockery of your life, because if you planned to go out in half an hour, someone else with your memories and personality would actually be going out, but would you ever know that this was going on?
If we assume that strong continuity of self is necessary to explain how things appear to us we should face the uncomfortable fact that things could appear exactly the same to us if it were failing on a frequent basis. Given this, we should question whether we have any reason to think that any strong continuity exists in the first place and, for this reason, I suggest that the idea of any strong continuity of self is a fallacy.
Can we salvage continuity of self at all?
We have no good reason to accept any strong continuity of self, but the concept can still serve us in a weaker form. Every day we have all sorts of views about other objects 'continuing' in more trivial ways, as I discussed previously, and there is no reason why we could not use the term 'continuity of self' in these more trivial, commonsense, contexts.
There is a further way in which we could use the idea of continuity of self. Previously, I discussed the survival motivation in humans and tried to show how our motivation to survive has evolutionary origins that have nothing to with ideas of strong continuity of self.
If we abandon any idea of a strong continuity of self then this survival motivation is no more than an 'allegiance': some configuration of matter - 'you' - exists now and some configuration exists in the future and it is because your abstracted survival motivation gives you allegiance to this future configuration of matter that it gets called 'you' as well. Asking why we should have such an allegiance is futile, as I mentioned previously: evolution has created systems that cause this allegiance to emerge in an abstract way and those systems are not based on nice, philosophical arguments. It could be argued that your brain owns you - not the other way around as many people think - and that it does not need philosophy to produce various motivations.
This position is different to that which most people would hold. Many would use the following two ideas:
- Survival is about preserving strong continuity of self.
- Some philosophical arguments may tell us what strong continuity of self is.
The 'survival as allegiance' view, however, suggests that:
- Survival is about allegiance to certain, future configurations of matter and this allegiance is caused by an abstracted motivation in the person holding the allegiance.
- Weak continuity of self, for our convenience, can be considered to be the property that these configurations of matter have in common by virtue of being the objects of the allegiance of this survival motivation.
It may seem as though I am suggesting that the 'you' that will exist in the next moment is not the same 'you' that exists now, and that all acts of self preservation are altruism, but I am not really saying this. An altruistic act would have to be directed at a different person - someone who is not you. For the 'you' in the future to be a different 'you' would imply that there is some meaningful concept of strong continuity of self and that we do not have it, or that it sometimes fails us. I am taking the position that strong continuity of self does not exist and that it is just as meaningless to talk about the 'you' who exists in the next moment being a different person, due to not having strong continuity of self, as it is to say that this future 'you' is the same 'you' that exists now due to successfully having strong continuity of self.
Once you discard strong continuity of self, the whole idea of differentiating between 'different' or the 'same' versions of you from moment to moment becomes incoherent. If that seems strange, consider our previous example of the car which has had many parts replaced. We could debate about whether or not it is the 'same' car but all we would be discussing is weak continuity and it would be an issue of convenience and semantics. Few would suggest that there is some strong, non-negotiable 'carness' that persists or does not persist. Does rejecting the idea of strong continuity for our car mean that is somehow a different car after some maintenance work? Not really: all it means is that we can discard both concepts of 'being the same' and 'being different as being without significance, at least if we expect them to apply in a strong way to a car. Once we discard strong continuity of self for ourselves as well, we are in the same position.
So, will life extension technologies work?
It should now be apparent that if we ask whether various life extension technologies can maintain 'continuity of self' then the answers are quite short and direct. For example:
- Can we show that strong continuity of self survives cryonic suspension? No.
- Can we show that strong continuity of self survives mind uploading? No.
- Can we show that strong continuity of self survives any other radical life extension process? No.
If we are going to be fair, however, we should accept that these questions are asking too much of life extension methods and we should consider other questions with possibly unpleasant answers:
- Can we show that strong continuity of self survives brain surgery? No.
- Can we show that strong continuity of self survives if you sleep for eight hours? No.
- Can we show that strong continuity of self survives while you see a movie? No.
- Can we show that strong continuity of self survives while you eat a cheeseburger? No.
Just as there is no firm philosophical argument that can show that any really extreme life extension method would be 'successful', so there is no firm argument to show that any of the things we do now are 'successful'. We just keep doing them anyway of course: evolution is very considerate that way! This is a consequence of discarding strong continuity of self.
What should we do?
Discarding strong continuity of self causes a problem: what should we do if offered an extreme life extension process? If firm philosophy has failed, does that mean that there is no basis for deciding? We should note that we have the same lack of justifiable philosophy to support strong continuity of self in our everyday lives, yet we have no problem in deciding what to do in conventional situations. We should be able to deal with this issue.
The most obvious approach is to use our common sense. Could we not simply use our intuitions in this matter, so that we run away from dangerous animals if we feel an overwhelming need to do so and make arrangements to have our bodies placed in cryonic suspension or our minds digitised if we feel similar feelings that we have to do this to 'survive'? A problem here is that this approach works adequately for situations which are very familiar to us, but it can fail us in situations that are so novel that we may feel unsure. Such situations may require more thought.
One obvious approach is to examine what we already find comfortable. We get through everyday life without having to philosophise to make survival decisions. We could use this experience and say that processes that are similar in nature, though not necessarily in detail, to ones we undergo are acceptable and processes that are radically different to ones that we have employed before are unacceptable. This approach itself is, however, conservative and it should be noted that, had it been adopted a few centuries ago, some of our advanced medicine would be regarded as conflicting with our survival motivation and would be considered unacceptable because it involved new processes, radically different in nature to anything that had been done before. It may work better as a 'minimum acceptability' argument, intended only to show that if we are to be consistent we should accept some processes that are not radically different from ones we already use, but not intended to give any idea at all about what processes we should not use, and in this sense it would be serving the same purpose as precedents in law courts. Proponents of cryonics could use this principle to argue that there is no process in cryonic suspension, or revival from it, that differs, except in degree, from anything that we now accept and point to all kinds of situations in which humans undergo significant disruptions in normal brain functioning and medical intervention in their brains without continuity concerns. This is a powerful argument for cryonicists to use and it can be regarded as appropriate even if some different approach is used, provided that this other approach also accepts current medicine.
There is an alternative, 'minimal philosophy' approach and we can see how it might work if we look at the underlying philosophy that supports many processes we already undergo. Taking a pill for a headache alters the brain chemistry, yet I have not heard anyone argue that it changes a person into someone else! Similarly, most of us appear to have few, if any, qualms about the issue of strong continuity of self with regard to brain surgery, all kinds of drugs to treat brain disorders and reviving a person using cardio-pulmonary resuscitation. We may have concerns about whether or not these processes will 'work' in a given situation, but our idea of what 'work' means rarely seems to include a consideration of continuity of self and anyone who argued that processes that we already use need justification in these terms would be unlikely to be taken seriously. The only reassurance that society needs is probably to see a patient at the end of it who appears to be happy and is grateful to his/her doctors. We could, adopting this standard with extreme technologies like mind uploading, regard a process as successful if it appears to be successful, in that somebody appears to be left at the end of the process who appears to have the original person's personality and memories and is grateful that the process was performed.
A more sophisticated approach, which I personally favour, would be one of 'abstraction'. Previously, I discussed how we can view our survival motivation as not being hard-wired into us, but instead being abstracted from simpler motivations. Some of this abstraction may occur by the methods that I described, but it is possible that some of it may occur by other means. Our survival motivation has probably undergone considerable abstraction during our lives and the extent to which this abstraction occurs has probably increased during the history of our species. Situations that may have worried people in the past are now routinely accepted by us because our survival motivation is more abstracted. It may be that our most sensible course of action is to extend this abstraction in a natural way. We could do this by determining what a natural abstraction of our existing survival motivation would be and adopting this survival motivation for situations that appear novel to us, using it to make decisions about radical life extension technologies. An approach like this could favour extreme proposals like mind uploading.
This article has suggested that strong, non-negotiable, continuity of self is a fallacy and that using it to assess the merits of various life extension technologies is flawed.
If strong continuity of self is a fallacy we should hardly be surprised. History has provided previous shocks. Knowledge of the solar system, and then of the wider universe, has relegated our place in space to one of no great importance and Darwin's theory of evolution by natural selection has relegated the complexity of our biology to being the results of mechanistic processes rather than a part of some divine plan.
After these historical ego bruises, could the next unwelcome surprise for humans be the knowledge that what we think of as the 'self' lacks any firm continuity, beyond what we define for our convenience? Maybe people in the future will regard strong continuity of self as a na´ve idea - one which their ancestors were lulled into because, like the earth centred universe, it may have seemed right, but one which could not be sustained against logical scrutiny.
 Unger, P. (1990). Identity, Consciousness and Value, Oxford: Oxford University Press.
 Bateson, P. and Martin P. (1999). Design for a Life: How Behaviour Develops. London: Jonathan Cape. Chapter 5.
 Levy, D.N.L. (1984). The Chess Computer Handbook, London: Batsford. Chapters 2-3.
 Heinz, E, A. (2000). Scalable Search in Computer Chess: Algorithmic Enhancements and Experiments at High Search Depths, Vieweg Verlag. Chapter 0.