Read Aloud the Text Content

This audio was created by Woord's Text to Speech service by content creators from all around the world.

Text Content or SSML code:

1 Substances Terminology The world consists of substances. Examples of substances, in the sense which I shall shortly begin to elucidate, are such individual things as this table and that chair, the tree over there, you and I. Substances have properties. Properties include both monadic properties, properties that things possess independently of their relations to things, such as being square or red, or having suchandsuch a mass or electric charge and relations alias relational or polyadic properties, such as being taller than, being to the left of, or lying between, that relate two or more things. Properties may be possessed by things of various kinds, including other properties and events but I shall be concerned almost entirely with properties possessed by substances. Events, as I shall understand the word, are the instantiations of properties in substances or other events at times, or the comingsintoexistence, existing or ceasingstoexist of substances at times. Events thus include both unchanging states, such as this tie being now green or Oxford being situated between London and Birmingham in 1991, and changes of state such as my car moving from London to Oxford yesterday, as well as things being made and destroyed. Substances are individual, concrete i.e. real, nonabstract things. Properties by contrast are universals, in that they can be instantiated in many different things. Being brown or being a table have many instances. But this table before me now is an individual there can be only one instance of it. The number 5 is also an individual there can be only one number five. But it is an abstract individual, created by an arbitrary act of language users. Abstract individuals are fictional individuals they do not really exist at all. There is a property of being fivemembered which belongs to groups of things under some description the group of things on my shelf described as bottles on my shelf has the property of being fivemembered. We then describe the situation as there existing a number, five, which is the number of bottles on my shelf and go on to say that this number exists, whether or not any group of things under any description has five members. It is, however, an arbitrary fiction, though in view of what we can do with mathematics a convenient fiction, to say so. 1 The table by contrast is no fiction it really does exist, whether or not recognized and described as a table. And hence it counts as a concrete thing. There are other individual, concrete things which are real enough, but talk about which is really talk about the other individual concrete things of kinds that I have already given as paradigms of substances. Smells and sounds, holograms and magnetic fields are real enough, but talk about them is reducible to talk about how things smell or sound or look to animals and humans, or how bits of metal behave. Talk about places too, and the space which they form, is, I suggest, just talk about how those substances that are material objects are or could be related to each other. To say that there is a place between this book and that book is to say that you can put another material object between the two books. Talk of times and the time that they form is, I believe, also reducible to talk about substancesbut as this is a more contentious issue, and one more important for my purposes, I shall postpone discussion of it until a later stage. Properties are only manifested in the concrete way in which substances exist when they are instantiated in substances. The property of redness is only manifested when there are red things. One could say that the property of redness exists, whether or not there are red things it exists waiting to be instantiated in things. But to talk in this way, as Plato did, is to create by linguistic fiat a fictional existence like that of the number 5 a misleading way of talking which I shall not endorse. Properties occur or are manifested, and may then be said to exist, when and only when they are instantiated in substances. Redness only exists when there are red things. Events occur at times, and may be said to exist then and only then. So properties can only exist as instantiated in substances, and events can only exist when substances exist. But that does not establish any priority in the scheme of things for substances, for substances can only exist in so far as they have properties, and some of those properties are essential to the substance being the particular substance it is. To be this desk, a substance has to be a desk, that is, to be similar in shape and construction to objects used by humans for writing at and to be used or designed for that purpose. And to be this tree i.e. the oak tree outside my window, a substance has to be an oak tree, that is, similar in shape, and appearance, and growth patterns, and genetic constitution to standard oak trees. Not all the properties of a substance, of course, are essential to itbeing brown is not essential to the substance that is my desk being that particular substance. Substances and, I think we should say, properties also exist all at once. My desk exists in its totality at a moment so too does the property of being brown, whenever something is brown. Events however do not exist in their totality all at once. My going from London to Oxford yesterday lasted for an hour, and what happened during the first half an hour was only a part of the event. Events thus have temporal parts. Substances exist all at once, but they persist through time from when they begin to exist to when they cease to exist. Substances can causally influence other substancesthey can bring them into being or destroy them, or cause them to gain or lose properties. The carpenter creates the desk, the painter makes it brown, and so on. I shall consider in Chapter 3 the alternative view, that it is events rather than substances that cause, and I shall reject that view. Those substances whose essential properties are such that they must occupy space i.e. be spatially extended I shall call material objects. The substance that is my desk could not be a desk unless it occupied space. Not all such substances are very naturally called material objectsfor example, the fundamental particles of physics of which the solid objects around us are composed, such as protons and electrons, do not seem very material in the natural usage of that term, but they count as material objects on my definition. 2 If there is a substance which does occupy space but need not, it does not count as a material object on my definition. Substances may have parts not temporal parts, but coexisting parts. My desk has drawers and a top. Those parts are then also themselves substances. Any substance which occupies space, as all material objects must, will have parts, because it will have spatial parts even if of physical necessity we cannot separate those parts. Being spatially extended it will have parts that occupy different regions of the space, of which the whole substance occupies the whole. Substances, including material objects, that are composed of other substances I shall call impure substances. There are pure substances that do not occupy space and do not have parts, spatial or nonspatial. A material object that does not have any nonspatial parts I will call a mere material object. My claims that some substances do not have others as parts, and that there are substances which do not occupy space are both highly contentious, and I will give arguments for them shortly. Anything designatable by a predicate that can characterize different things, and in particular substances and groups thereof, is, as I shall understand the notion, a property. Some philosophers have wished to restrict the notion property so that not all predicates designate properties. On this restrictive view only those characteristics picked out in scientific laws as making a difference to the way things behave are properties. Thus being exactly 2.351 miles away from the Eiffel Tower makes no difference to the way something behaves and so is not a property, whereas being 4,000 miles from the centre of gravity of the Earth does make a difference and so is a property. And on this view predicates that pick out characteristics that make the same difference really pick out the same property, though it may take a scientific discovery to show thata gas having a certain temperature is the gas having the same property as it having molecules with a certain mean kinetic energy. One could talk this way, but if one did, one would needin order fully to describe the worldanother word than property to designate what is picked out as belonging to things by nonsynonymous predicates. I suggest that it makes for a neater description of the world if we so understand property that with a small exception to which I will come in Chapter 2 every predicate designates a property, and every nonsynonymous predicate designates a distinct propertyeven if some properties make no difference to the way things behave and others, such as a gas having a certain temperature and having its molecules with a certain mean kinetic energy, always go together. Our knowledge of the world by observation is basically recognition of which properties are instantiated when. For we pick out substances as the substances they are almost entirely by the unique combination of properties which they manifest. We pick out a certain desk largely by its monadic properties being red, and of suchandsuch a shape and its locationin a certain room picked out by its propertiesthe one at the top of the staircase marked 8. An indexical element does, however, also finally enter inwe may need to distinguish between particular substances with otherwise identical properties by their relations to me e.g. on my left, me not being distinguishable from other substances solely by my properties. On this, see further Chapter 2. With substances, unlike properties, however, there is a lot more to them than appears on the surfacethey have parts and an inner nature of which initially we may be unaware. Material objects are composed of form and matternot in the sense that they have these as parts, but in the sense that they are chunks of matter possessing certain properties, some of which are essential to an object being an object of its particular kind. A substance continues to exist while more or less the same chunk of matter continues to exist and continues to possess those essential properties. The essential properties are the substances essential form. My desk is composed of certain matter wood on which is imposed a certain form that of a desk, and while more or less the same wood is organized into forming a desk, the substance continues. The coming into existence of a material object consists in the imposition on matter of the objects essential form its ceasing to exist consists in that matter no longer being organized so as to possess that form. In the case of substances of some kinds, for example, plants such as trees, the matter does not need to remain even more or less the same it suffices that the new matter be obtained by gradual replacement of the old. It is a somewhat arbitrary matter how one cuts the matter of the world up into chunks, and under which forms one traces the continuity of matter i.e. which properties of a chunk of matter one regards as the essential ones. Some chunks of matter have more of a natural unity to them, in the sense of their remaining chunks for a longer time and there being many more and more influential causal interactions between the different bits of the chunk than causal relations between the chunk and the outside world, than do other chunks. And if we trace the chunks under certain forms rather than others, they will continue to exist for longer and make more evident differences to the world. Regarding the chunk of wood which forms my desk as a relevant chunk, rather than the chunk which forms the left half of my desk and the floor beneath it, picks out a chunk which continues as a whole because it sustains itself in being through causal interactions between its parts. And regarding the chunk as essentially a desk rather than as essentially adeskusedforwritingphilosophy allows us to trace a more useful form of continuity, for example, because it makes similar differences to the carpet beneath it and to the way it is valued by antique dealers whatever its use. But what should be apparent is that there are innumerable different ways of cutting up the world into chunks and tracing continuities, and that the differences between them concern matters of degreedegree of internal causal unity, persistence, influence on thingsso that it is unjustified to say that there is one correct way of describing the world. Some philosophers have wanted to say that there is one correct way of describing the world, which we get by recognizing as substances only things whose essential properties are those of a natural kind. Those properties which are fundamental in determining the behaviour of matter in accord with natural laws come together in bundles and are instantiated in things which behave in fundamentally different ways from other things. Thus each kind of chemical elementiron, copper, or hydrogen, for exampleforms a natural kind, because the properties which make an atom of one kind rather than another e.g. the number of protons in the nucleus of the atom are fundamental in determining the behaviour of those atoms. Those bundles of properties then constitute a natural kind, and an object is a substance only if its essential properties are those of a natural kind. So an atom of iron is a substance, whereas a heap of unconnected atoms is not. But groups of atoms of different elements, joined together in ways that form objects picked out as distinct from other objects by essential properties fundamental in determining characteristic behaviour, are also substances, because they too belong to natural kinds. Thus each species of plant elm tree, or oak tree, say forms a natural kind, because picking out chunks of matter as plants belonging to a species involves picking them out by properties namely, those of the genotype underlying the characteristic colour and shape of the plant fundamental in determining the behaviour of those chunks in accord with natural laws. But useful though these particular ways of classifying are, they provide neither an exclusive nor an exhaustive system of cutting up the world into substances. Each oak tree has various chemical element atoms as parts of it. And many things which have a natural unity to them, such as sticks and stones and human artefacts, do not belong to any natural kind. Rather, there are different systems of describing the history of the world, some of them more useful than others. Hence it seems proper to regard as a substance anything including the thing currently formed of the left half of my desk and the floor beneath it traceable through time under a form that is, a system of essential properties which it has to preserve in order to be that substance. One can regard the thing currently formed of the left half of my desk and the floor beneath it as having an essential shape and appearance, and as continuing to exist while roughly the same matter preserves that shape and appearance. That thing which we have now formed the concepts to recognize is a substance, and would be one even if we never picked it out as such. The world is full of innumerable, unrecognized, and unevident substances. To tell the full history of the world, or any spatiotemporal segment of it, however small, we have at least to describe fully the continuities of matter and the properties exhibited by chunks thereof and some of the many ways of doing this will entail others. A description of what happened to all the atoms will entail what happened to all the larger objects composed of them. But it is characteristic of any impure substance that we can tell the full history of the world without needing to mention it or anything which has it as an essential partwe need tell only what happened to its parts, or to other substances whose essential parts include its parts. I tell you what happened to my desk if I tell you what happened to a substance consisting essentially of the left half of the desk and something else, and also to a substance consisting essentially of the right half of the desk and something else. Many of our ordinary language terms for picking out substances leave somewhat vague the conditions for their correct applicationit is often unclear how much original matter has to remain, and also whether it can be disassembled and reassembled, for the same substance to persist. But language can always be improved so that its terms have even more precise conditions for their correct application. There is a philosophical distinction between phasesortals and substancesortals. A sortal is simply a word which applies to a substance in virtue of some property or properties which belong to it, for example, boy, desk, or red object. A substancesortal is a word which applies to a substance while it has its essential form, that is, while it exists at all. A phasesortal is a word which applies to a substance while and only while it has certain of its nonessential properties, while, that is, it goes through a phase of its existence. Thus, it is said, oak tree is a substancesortal, because while the substances which are oak trees exist, they cannot but be oak trees whereas sapling is a phasesortal, because the substance which is a sapling may continue to exist when it is no longer a sapling, but becomes a fullgrown tree. Nevertheless if a and b are the same substance at one time, they will be the same substance at all timesfor a thing cannot cease to be identical with itself this principle is known as the necessity of identity. The sapling is the same substance as the fullgrown oak, even though we will not describe it as a sapling when it is fullgrown. Among substancesortals, are narrowest substancesortals which pick out substances in virtue of the largest conjunction of properties that must belong to a substance while it has its essential form. Thus, if oak tree is a substancesortal so is tree but oak tree is a narrower substancesortal than tree. A given substance which is an oak tree then has to remain an oak tree in order to continue to exist, merely remaining a tree will not suffice. If a given oak tree can lose or gain any properties so long as it remains an oak tree, then oak tree is a narrowest substance sortal, it picks out the minimum essential form or kind to which particular oak trees belong. Our understanding of some referring expression as picking out a substance involves an understanding of what it is, what must be the case for some expression on another occasion to pick out that same substance, and so an understanding of the minimum essential kind under which we trace its continuity. It follows that if a is the same as b is true, a is the same ϕ as b is also true, where ϕ is any substance sortal which applies to a, including the narrowest substancesortal, and conversely. And the same holds if ϕ is any sortal at all, not just a substancesortal. For given that a sortal must apply to a substanceeven if technically it is not a substancesortal, being the same ϕ as entails being the same substance which is ϕ as which entails being the same substance as. ϕ simply picks out a property that is preserved along with sameness of substance. If a is the same red object as b, there is something which a and b both are, and that can only be if there are criteria of identity associated with that thing. So if a is the same ϕ as b, it is the same substance as b, and so there can be no ψ such that a is ψ but not the same ψ as b. The suggestion that it is possible for a substance a which is ϕ and ψ to be the same ϕ as b but not the same ψ as b, is the suggestion of the possibility of relative identity, an identity that is not absolute, but only relative to a sortal. Various examples have been put forward in recent years of possible cases of relative identity. 3 Suppose a statue of Napoleon made of brass, a, gradually to have its old brass replaced by new brass, so that a new brass statue is formed, b. Is it not the case, asks the champion of relative identity, that a is the same statue ϕ as b, but not the same lump of brass ψ as b But the question must be asked, does a pick out a statue made of brass, or a lump of brass formed into statue shape Is a essentially a statue, or essentially a lump of brass If the former, then a is not as such a lump of brass, although it is made of brass. If the latter, a is not as such a statue, although it may be formed into the shape of a statue. Neither being made of nor being formed into is the same as being the same as. It may be said that we are often unclear in using an expression designed to pick out a substance, just what kind of thing we are picking outthat is, what is the minimum essential kind to which it belongs. No doubt, but to that extent there is no clear meaning to a is the same ϕ as b. It cannot be the case where a and b have clear criteria of use, and ϕ and ψ are sortals, that a is ϕ and ψ, the same ϕ as b, but not the same ψ as b. However, as I have pointed out, there are many different ways of cutting the world up into substances. The same phenomena can be described by the same words with a slight change in the meaning of these words. A word previously used as a phasesortal may be used as a substancesortal, or conversely. We could think of what happens when the sapling ceases to be a sapling, as one substance ceasing to exist and a different one coming to be formed from the molecules of the sapling. We could describe this by saying the sapling ceased to exist, and the oak tree began to exist and in that case we would have turned sapling into a substancesortal, and restricted the range of plants which count as oak trees. This would be a less useful but possible way of talking. But it remains the case that for any given way of cutting up the world relative identity is not possible. There are substances, however, other than material objects, that, I shall argue, are pure substancesones which do not have other substances as parts. We human persons have two partsa body, which is a mere material object, and an immaterial part, a soul, which is a pure substance. As I have argued for this view at some length elsewhere, 4 my arguments here will be fairly brief. 5 Humans Body and Soul It will be useful to begin by distinguishing, among properties, between physical and mental properties. I understand by a physical property one such that no one individual has necessarily a means of discovering that it is instantiated that is not available to any other individual. Physical properties are public there is no privileged access to them. Thus, having a mass of 10 pounds, being 8 feet tall, and being square are all physical properties. So too are the typical properties of neurones in the brainbeing in suchandsuch an electrical state or releasing a transmitter chemical. Anyone who chooses can find out by the same means as can anyone else whether something is 8 feet tall, or in a certain electrical state. Physical events are those that involve the instantiation of physical properties. Mental properties, as I shall understand the term, are ones to which one individual has privileged access, that is, he has a means for discovering whether they are instantiated that is not available to anyone else. Such properties as being in pain or having a red afterimage, are mental, for any individual in whom they are instantiated does seem necessarily to have a way of knowing about them not available to anyone else. For whatever ways you have of finding out whether I have a red afterimage e.g. by inspecting my brainstate or studying my behaviour I can share yet I have an additional way of finding this outby my own awareness of my own experience. Mental events are events which involve the instantiation of mental properties e.g. John being in pain at midday yesterday. Some mental properties have physical properties as components. Some property has another as a component if the instantiation of the former entails the instantiation of the latter. Raising an arm intentionally entails having an arm rise. The former is a mental property for the person in whom it is instantiated has a means of knowing that it is instantiated not available to others I know in a way others cannot do whether any arm rising was intended by me, because I alone can form my intentions. But having an arm rise is a physical propertyanyone can observe as well as anyone else whether someones arm rises. I shall call a property a pure mental property if it has no physical components. Impure mental properties have both pure mental and physical components. Analagously pure mental events are ones which do not have physical events as components i.e. entail their occurrence impure ones do have physical components. There are, I suggest, five kinds of pure mental event that characterize humans, which I shall call sensations, thoughts, purposings, desires, and beliefs. 6 By sensations I mean experiences of the kind normally brought about by the senses or ones similar thereto in experiential content, such as my experiencing the patterns of colour in my visual field, sensations of taste or smell, mild aches and pains, sensations of hot or cold in parts of my body together with their pale imitations in my recalling memory images or my imagining imagined images. By thoughts I mean those datable conscious occurrences of particular thoughts that can be expressed in the form of a proposition. Often these are thoughts that occur to a person, flit through his mind, or strike him without him in any way actively conjuring them up. It may occur to me that today is Tuesday, or that this is a receptive audience, or that the weather is cold. By a persons purposings I mean his endeavourings to bring about some event, meaning so to do. Every intentional action, everything that a person does meaning to do it, consists of the person bringing about some effect or trying but failing to do so. Yet when the person brings about some effect, their active contribution may be just the same as when, unexpectedly, they try but fail to bring about the effect. When I move my hand, I bring about the motion of my hand. Normally this action involves no effort and is entirely within my control. But on some occasion, I may find myself unexpectedly paralysed. My active contribution is the same as when I move my hand successfully. For this intentional contribution, for an agents setting himself to bring about some effect even when effort or failure is not involved I will use the word purposing. A persons beliefs are his view of how the world is, his picture of how things are. A persons desires are his natural inclinations to do things, experience things or have things happenwhat he feels naturally inclined to do or let happen, if he has the opportunitybut for contrary desire, or some strong effort of will, that is, purposing, to do otherwise. Beliefs and desires are continuing mental states, states that are mental because the subject can make himself aware of them if he chooses, but that may exist for a long period of time while he is unaware of them, asleep or doing other things. Sensations, thoughts, and purposings, by contrast, are conscious episodesif we have these, we must to some extent be aware at the time of having them. In order to tell the full history of the world I need to say not merely which physical properties have been instantiated, but which mental ones too. I need to say not merely what has been going on in your brain in terms of which electrical circuits have been set up by the transmission of which chemicals, but also which sensations and thoughts you had. But if we supposed that human beings were mere material objects and that mental properties having this or that sensation or thought were properties of those material objects, something allimportant would have been left out. For full information about which physical and mental properties were instantiated in which mere material objects would still leave one ignorant of whether some person continued to live a conscious life or not. Knowledge of what happens to bodies and their parts will not show you for certain what happens to persons. This point is illustrated very clearly by the example of brain transplants. The brain consists of two hemispheres and a brain stem. There is good evidence that humans can survive and behave as conscious beings if much of one hemisphere is destroyed. Now suppose my brain hemisphere plus brain stem divided into two, and each halfbrain taken out of my skull and transplanted into the empty skull of a body from which a brain has just been removed and there to be added to each a halfbrain from some other brain e.g. the brain of my identical twin whatever other parts e.g. more brain stem are necessary in order for the transplant to take and for there to be two living persons with lives of conscious experiences. Which would be me Probably both would to some extent behave like me and make my memory claims for behaviour and speech depends, at any rate in very large part, on brainstates, and there is a very considerable overlap between the information carried by the two hemispheres that gives rise to behaviour and speech. But both persons would not in a strict sense be me. For if they were both identical with me they would be the same person as each other if a is the same as b, and b is the same as c, then a is the same as c and they are not. They now have different experiences and lead different lives. I shall consider a little later whether in some attenuated sense, both could be me, that is, my successor persons, but there are three other clear possible outcomes of the transplantthat the person with my right halfbrain is me, or that the person with my left halfbrain is me, or that neither is me. But we cannot be certain which holds. It follows that mere knowledge of what happens to bodies does not tell you what happens to persons. It is tempting to say that it is a matter of arbitrary definition which of the four possibilities is correct or three possibilities, if we rule out both persons being in some sense me as selfcontradictory. But this temptation must be resisted. There is a crucial factual issue herewhich can be shown if we consider the situation of someone knowing that his brain is about to be split, knowing that the person to be formed from his left halfbrain is to have a life of great enjoyment and the person to be formed from his right halfbrain is to be subjected to a life of great pain. Whether I shall have an enjoyable future life is a clearly factual question only someone under the grip of some very strong philosophical dogma would deny that, and yet, as I await the transplant and know exactly what will happen to my brain, I am in no position to know the answer to what will happen to me. Maybe neither future person will be meit may be that cutting the brain stem destroys a persons connection with that brain once and for all, and repairing the severed stem creates a new human person, so that the whole process creates two new conscious human persons, neither of whom is me. Perhaps I will be the left halfbrain person, or maybe it will be the rightbrain person who will be me. Even if one subsequent human resembles the earlier me more in character and memory claims than does the other, that one may not be me. Maybe I have survived the operation but am changed in character and have lost much of my memory as a result of it, in consequence of which the other, subsequent person resembles the earlier me more in his public behaviour than I do. And even if there is the possibility that both later humans are to some extent me, neither science nor philosophy could show conclusively that that, rather than one of the other three possibilities, was the actual outcome, for all the evidence which could ever be obtained would be compatible with the other possibilities as well. Reflection on this thought experiment shows that however much we know about what has happened to my brain and other parts of my body, we are not necessarily in a position to know what has happened to me. From that it follows that there must be more to me than my brain, a further immaterial part whose continuing in existence is necessary if the brain and so body to which it is linked is to be my brain and body, and to this something I give the traditional name of soul. I thus use the word soul as the name of a kind of substance, as did Descartes and not as the name of a kind of form, a way of living and behaving, as did Aristotle. I am my soul plus the brain and body it is connected to. Normally my soul goes where my whole brain goes, but in unusual circumstances such as when my brain is split it is uncertain where it goes. Take a slightly different example. I die of a brain haemorrhage which todays doctors cannot cure, but my relatives take my corpse and put it straight into a deep freeze in California. Shortly thereafter there is an earthquake as a result of which my frozen brain is split into many parts, a few of which get lost. However, fifty years later, when medical technology has improved, my descendants take the 20 bits of my broken corpse, warm it up and mend it, replacing the missing parts from elsewhere. The body becomes the body of a living person which behaves somewhat like me and seems to remember quite a lot of my past life. Have I come to life again, or not Maybe, maybe not. Again there is a truth here, about whether I have survived the haemorrhage as I wanted to, and yet a truth of which we cannot be sure however much we know about the story of my brain, and however much we know about the mental lives of the earlier me and the later revived person. Hence, my survival consists in the continuing of something else, which I call my soul, linked to my previous body and I survive in this reconstituted body only if that soul is connected with it. These two thought experiments show that something else than my body has to continue if I am to continue, and that something else I have called my soul but they do not show that the continuing of that alone is all that is necessary for my survival. Maybe, as far as these thought experiments show, some of my brain has also to continue to exist if I am to continue and in that case I would be a material object, though not a mere material object. Other thought experiments can be adduced to rule out that suggestion, but to show that no part of the body need continue to exist if I am to continue, I prefer at this stage to adduce a straight philosophical argument to be found in embryo in Descartes. In this argument I use the notion of the logical possibility and I had better state briefly what I understand by this notion, and the associated notions of logical necessity, contingency, and impossibility. A more thorough treatment of these notions will be provided in Chapter 5. The logically necessary is what could not but be for reasons of logic to deny it is ultimately to contradict yourself. It is logically necessary that any red object is coloured, that all squares have four sides, and that 5 7 12. The logically impossible is what cannot be for reasons of logicsuch as there being a red object which is not coloured. The logically contingent is that which is neither logically necessary nor logically impossiblesuch as there being six chairs in my room, or there being seven chairs in my room. The logically possible is whatever is either logically contingent or logically necessary. The logically contingent is the world being this way rather than that, when both ways are logically possible. My straight philosophical argument begins by claiming that it is logically possible that I who am now conscious might continue to 21 exist if all my body were suddenly destroyed. I could have just mental propertieshave thoughts, and sensations, and purposeswithout having a body. And surely it must be that any religious believer who claims that he will live after the destruction of this body and without acquiring a new body does not contradict himself anyone can understand the claim that he is making because it is a coherent one. The argument then goes on to claim that if anything is to continue to exist over time, either the whole or some part of it must continue to existand that is surely true of anything. My desk cannot continue to exist, if every part of it is destroyedand so on. So, the argument concludes, if it is to be logically possible that I survive when all my body is destroyed, there must now already exist another part of me an immaterial part whose survival guarantees my survivaland that I have called the soul. 7 My mere existence as a conscious person at some time entails that I have an immaterial part, which I call the soul, at that time and if I do survive, the argument shows that it is sufficient that that part survivesfor my survival is compatible with all else being destroyed. Hence I am not a material object, since I can exist without occupying space. The pure mental properties which are instantiated in human beings belong to them in virtue of belonging to their souls. For pure mental properties could not be instantiated in mere material objects such as bodies or brains, since the instantiation of a pure mental propertysome individual being in pain, for exampleleaves open the possibility that some earlier individual was the individual who would later have that experience and so would have reason in advance to fear it or hope for it. But since knowledge of what has happened to mere material objects is not sufficient to show whether some earlier individual was so positioned, whereas knowledge of what has happened to souls is sufficient, but would be sufficient only if the pure mental property was instantiated in a soul, the pure mental property must have been instantiated in a soul. Pure mental properties characterize souls, not bodies. Impure properties characterize soul plus body. So I have argued that there are immaterial as well as material substances. Human souls are such immaterial substances, and so too are any other immaterial subjects of mental properties whom I also call souls. I believe that the higher animals are animate beings, that is, are subjects of mental properties, and hence by my previous argument they too have souls. If those individuals who are animals can also exist in a disembodied stateas I believe, but have not arguedthen they are essentially souls, as are humans. But if a dog, Fido, say, has to have a body in order to exist, then it would be a material object but, because it has a soul as an essential part, it is not a mere material object. Humans and animals on this earth both have bodies as well as souls although the bodies are nonessential parts of, at any rate, humans. Are souls pure substances Alternatively, do they have parts, that is nonspatial parts I think not. They are pure substances. If a substance has parts, then there are properties which characterize only a part but not the whole or characterize the whole in virtue of characterizing a part, or characterize the whole in virtue of different properties characterizing different parts. Each of the seven drawers of my desk weighs 8 lb., the top weighs 5 lb., and hence the desk weighs 61 lb. The whole desk is brown because all its external surfaces are brown, even though not all the external surfaces of the drawers are brown. And so on. Similar points apply to the relations between a human being and its parts, body and soul. The human weighs 100 lb. because its body weighs 100 lb. The human walks, because its soul purposes to walk, its bodys legs make walking movements and the former causes the latter. But there are no analogies here for the soul. Each pure mental property that characterizes the soul, the subject of experience, is fully present to that subject. There is no part of the subject that experiences some property which contributes to the whole experiencing a different property. It is the same I who have a blue afterimage, hear your voice, think about breakfast, decide to go for a walk and no part of me has the one experience and not the other although the parts of the brain that cause me to have the different experiences are different. It is difficult to see how fission or fusion of humans and thus of their essential parts, their souls, could take place unless souls had parts. For fission involves the splitting of something previously joined together and fusion the joining together of things previously separate. And if souls do not have parts, that explains why fission and fusion of souls and so of humans are not possible. And 23 there are independent arguments to show that fission and fusion are not possible. Some writers, notably Derek Parfit, 8 have supposed that what happens and not merely could happen, but would happen in the splitbrain experiment, is that although both later humans would not, strictly speaking, be me, they would be my successor persons, partly me, my later selves. Just as two later cars each formed from some parts of one earlier car and other parts as well, would be both in part the same car as, in part a different car from the earlier car, it would be the same, Parfit claims, with humans. This would be fission. But there is a powerful objection to the coherence of supposing that animate beings, unlike inanimate things, can split. If I became partly both the later humans, I would presumably in part have both their experiences yet how on earth can this be, since there would be no one person who has simultaneously the experiences that each of the subsequent persons has at a given time There are similar logical difficulties in the way of fusion. The soul, and so the human being, is a subject of mental properties. It only exists in so far as it is capable of a mental life. It follows that it must be logically possible that a person and so his soul have experiences of his continuing existence at each moment of that existence. Now no human could have the experience of himself as being formed from the fusion of two humans. For suppose P 2 to be formed from the fusion of P 1, and P 2 . If P 2 was so formed and having experiences while being so formed, it would seem that he must have two incompatible experiences at the same time. He would have to experience himself as experiencing P 1 s experiences in a continuing stream as they occur and coming suddenly to acquire awareness of P 1 s experiences subsequent to their occurrence and also as experiencing P 1 s experiences in a continuing stream as they occur and coming suddenly to acquire awareness of P 1 s experiences subsequent to their occurrence. The experience of fusion cannot be described coherently which suggests that no subsequent human can in any real sense to any degree be both of two earlier humans, for if he could, he ought to have been able to some extent to have experienced both their experiences. Continuity of experienceone individual being the same individual as had or will have some experience is a very important The Nature of Humans What makes an animate being i.e. one characterized by some mental properties, and so having a soul a human being homo, man, in the sense in which both females and males are men as opposed to, say a mere animal, a Martian, an angel, or God I argued earlier that the human soul is characterized by the continued or intermittent possession of mental events of five kinds. It may, however, well be that not all the higher animals who have mental events have mental events of all these kindsmaybe some of them, for example, do not have occurrent thoughts. But the principal difference between the mental life of human souls and the mental life of animal souls lies, I suggest, in the normal human soul, in contrast to animal souls, having further properties characterizing its mental life. The human soul is capable of logical thought of drawing out mentally in a sequence of thoughts the consequences of earlier thoughts, and of moral awareness having beliefs about actions being obligatory or, more generally, good it has free will its purposings, i.e. initiations of actions, not being fully caused by earlier events, and it has to it a structure beliefs and desires are kept in place by other beliefs and desires we have and see ourselves as having various beliefs and desires because we have other beliefs and desires which give them support. That the first two and possibly the fourth of these further properties characterize humans and not animals is fairly obvious. Whether humans have free will of this kind, that is, libertarian free will is highly disputable I 25 have argued elsewhere 9 that they do. Not much turns on this for present purposes, but I shall need in a much later chapter to assume that humans do have libertarian free will. All of this suggests a theory of a human being as constituted by a human soul, one having the above characteristics, connected to a human body, defined as one largely similar in its anatomy, physiology, and capacities for action e.g. running, talking, etc. that can be realized through it, to the paradigm examples of human bodies those of our friends and neighbours by which we are surrounded. The connection involves the subject being able to operate on the world through that body his purposings to move the limbs of that body are efficacious and make a difference to the world, acquiring beliefs about the world through that body stimuli impinging on the eyes and ears of that body give him beliefs about how the world is, feeling things in and desiring to act through that body. However, this theory of human nature may be challenged on various grounds as not sufficient, or as not necessary. I consider first the challenges to its sufficiency. The first objection which is related to a similar challenge to its necessity is the objection that man, unlike, say desk, is a naturalkind word. Natural kinds are, we saw earlier, kinds picked out in virtue of essential properties that are fundamental in determining the behaviour of things in a world with natural laws. But although we may reasonably conjecture because of their characteristic appearance and patterns of behaviour that most objects with certain observable properties belong to the same natural kind, that is have in common essential properties fundamental in determining behaviour, we may not know what those essential properties, which determine the exact boundaries of that kind, arescientists may not yet have found that out. What makes something a desk is a matter of observable features e.g. shape and solidity. But what makes something water is not its taste, its transparency, its density, etc., but its chemical composition H 2 O, which underlies and is causally responsible for the observable properties. Something with the same observable properties but a different chemical composition would not be water. If we did not know the essence of water as we did not before the nineteenth century, we could go badly wrong in our judgements about which samples of liquid are samples of watereven if we were the best experts available and took much trouble. Conversely, something with the chemical composition of water but which, because of external factors change in our taste buds, odd lighting and atmospheric conditions, etc., tasted or looked differently would still be water. Its observable features are normal but not completely reliable indicators that a substance before us is water. 10 So, the argument goes, 11 human is like this. The features which I have listed, by which in general we rightly judge something to be a human, are largely experienceable or observable, but what makes something to be a human is the essence which underlies the observable features of most paradigm examples of humans and is causally responsible for those observable features. The latter features which, following Putnam, I shall call the human stereotype, are only features of a human if the underlying essence that gives rise to them is the same as in standard examples of humans and sometimes the essence might be present without the stereotype. What sort of essence are we talking about As regards bodily features, genetic constitution is the obvious analogue to chemical constitution. Whether genetic constitution is causally sufficient to produce a human soul may be doubted, 12 and what else has to be added to it to produce a sufficient cause for the human soul is totally unclear. However, whatever the underlying cause of the stereotypic features, the issue remains whether human is a naturalkind term like water or instead a term like desk. Why should not someone with the stereotypic features that I have listed be a human, even if those features were brought about by a quite different cause from the one that operates in normal humans It seems to me that our criteria for the use of the word human are simply unclear here. Some speakers might A similar response, in my view, must be given to the other two objections that I shall consider to the sufficiency of my suggested list of essential features for humanity. The next is what I shall call the limitation objection. It is the objection that the powers and knowledge of an individual must be limited to some extent if he is to be a human. An individuals powers over the world outside himself must be confined almost entirely to ones that he exercises through his human body his knowledge about the world must be confined almost entirely to that obtainable through its effects on his body namely, through his senseorgans. An individuals powers to move the furniture about must be confined almost entirely to the power of moving it with his arms or legs, and his knowledge of where it is must be confined almost entirely to what he sees or feels or someone tells him. A small amount of telekinesis and telepathy might perhaps be compatible with humanity, but too much means that we no longer have a human. A human who becomes able to move mountains on distant continents just by willing, or knows what is going on in distant galaxies without using a telescope or listening to what others tell him ceases to be a human. Such is the claim of the objector. But whether his claim is correct seems to be quite unclear, because some of us might use the word human in such a way that someone with such superhuman powers could not be a human, whereas others might use the word human in such a way that someone with superhuman powers would be a human so long as he had normal human powers as well. Our criteria for use of the word human are just not precise enough for there to be a right answer as to whether the possession of powers far beyond those of normal humans would rule out someone from being a human. The final objection to the sufficiency of the listed features is what I shall call the historical objection. Even if my listed features are caused by the genetic or other essence, a being cannot be a human, the objection goes, unless his ancestry is rightunless the physical causes, namely, the genes, come from human parents or are otherwise obtained from the gene pool of the human race. 13 If we make an ovum in a laboratory, synthesize its genes from inorganic material and fertilize it with a similar synthesized sperm cell, implant it in a tissue culture and grow the embryo in an artificial environment, the resulting being would not be humaneven if the genes involved are qualitatively similar in chemical makeup to human genes. To be human you have to belong to the human race. Once again, whether our criteria of humanity involve a historical criterion seems to me unclear. If they do, the further question arises how thoroughly that criterion has to be satisfiedif for example, an individuals genes come only from his mother parthenogenesis, can that individual still be a human I would have thought that the use of the word human by most of us is such as to yield the answer Yes to the latter question. I come now to objections to the necessity of my conditions for humanity, that to be a human an individual must have a human soul with the listed features, connected with a human body, defined as such by its physiology, anatomy, and capacities for action. First it may be objected that an infant who has only potentially some of the listed features ought to count as human. That seems right, whether or not we insist that the right causal essence ought to lie behind the infants potentiality to develop the listed features. So long as normal growth will lead to the infant possessing the listed features, that infant is human. Secondly, why should we insist on all the listed mental features Could there not be a human who did not have sensations, but could acquire beliefs about his environment through bodily processes without their being mediated via sensations 14 Ora question of especial relevance to a later chaptercould there not be a human who was not subject to desire, or at any rate to desire to do any action which he believed morally wrong Again, our criteria for humanity yield no clear answer. The final difficulty with the suggestion that the conditions stated earlier are necessary isis the human body necessary Is not a evolutionary history is an important criterion used by biologists for distinguishing disembodied human possible and, if so, could there be a human who was never embodied but was human in virtue of the type of mental life he had, including sensations of a kind caused in other humans by bodily processes, and desires of a kind manifested in other humans through bodily movements Now I did earlier assume that I who am human could become disembodied, but my question here is not quite the same and the answer is not quite as obvious. If someone who is human cannot but be human, then since I can become disembodied, it would follow that having a body is not necessary for being human and if, as earlier discussed, some kind of genetic constitution was involved in being human, the involvement could only be that any body a human has would have to be caused by a certain constitution, even if he could be human without having a body and so having that genetic constitution. But if I who am human can become disembodied, and yet being embodied is necessary for being human, what follows is that being human is not an essential property of those individuals who are humanone could cease to be human and become a being of some other kind, while remaining the same individual just as a child can cease to be a child and become adult, while remaining the same individual. In the technical terminology introduced earlier, human would be a phasesortal rather than a substancesortal. It should be clear that with our rough present usage of human there are different ways of making that usage precise. Someone clearly is human on any understanding if he satisfies all my original conditions, together with an underlying essence condition, the limitation condition, and a historical condition to meet each of the three objections to the sufficiency of the original conditions. But you get wider and wider understandings of humanity as you drop more and more conditions. There comes a point obviously where it is unreasonable to call a being humanwhere hardly any of the conditions apply. But there is plenty of scope for different explications of what it is to be human. Yet on any plausible explication of our normal usage, human cannot be a substancesortal and so being human cannot be an essential form. For the body of some human, call him John, could gradually be turned into an animal body, into a body to all appearances like that, say, of a gorilla and even if we insist on conditions of genotype or origin for a body being that of a gorilla, whatever else the body was it would not be 30 that of a human. And Johns human soul could gradually become a soul capable only of a gorillalike mental life. The resulting bodyandsoul would not be a human being, whatever else it was. Yet John would still exist. For suppose John knew in advance what was going to happen, and knew too that the gorilla would suffer much pain, he would rightly fear that pain for the same reason as he would fear any future pain of his. The same subject of mental properties could persist through the change. That shows that we name individuals who are humans in such a way that what is essential to their continuing to exist, namely their souls continuing to exist, is not those souls continuing with peculiarly human properties, let alone connection to a human body. So there is no need to reform usage in order to turn human into a phasesortal it is one already. But what is unclear in our present usage is just what are the boundaries of being human. How much by way of powers an individual has to gain or lose in order to cease to be human is unclear. But it follows from my earlier arguments that I and any other human who gain or lose powers or body am essentially a soul, a subject of mental properties, someone with a capacity for feeling, thought, or intentional action. Souls are immaterial substances. There may also be pure immaterial substances other than souls, but souls are those substances capable of having mental properties. Among souls are souls of different kinds, differing in the kinds of mental life they are capable of and the kinds of body they are connected with. A normal use for the word person, which I shall adopt, is to call someone a person if he has a mental life of at least the kind of richness and complexity which humans have or is capable of such a life, i.e. would have it as a result of normal processes of growth. Then, given that use, as well as humans, angels as traditionally depicted, and many fictional inhabitants of other planets as described in works of science fiction whom we may call Martians, would also, if they existed, be persons. I shall not use the word person in a very precise way, and so there is no need for me to define kind of richness and complexity, which would be needed if I were to try to give a precise sense to person. Person must also, however, in this normal use, be a phasesortal, since an individual could cease to have a mental life of that complexity and yet in continuing to have sensations, continue to exist. A crucial question about souls is whether they too, like material 31 objects, are composed of form and some sort of stuff analogous to physical matter. I shall come to that question towards the end of the next chapter. Souls of some kinds may be able to become souls of other kindsit is logically possible. I have argued that it is logically possible that a human soul could become the soul of a nonhuman animal, and I suggest also that a human soul could become a very powerful disembodied spirit. But there may be logical limits to such change. There may be souls which, given that they are of one kind, could not possibly become souls of various different kinds. I shall raise this issue again when we come to discuss the divine nature in Chapter 7.