Outside such a theistic framework, the theory is incredible. One category of arguments for dualism is constituted by the standard objections against physicalism. Because this argument has its own entry see the entry qualia: the knowledge argument , I shall deal relatively briefly with it here.
One should bear in mind, however, that all arguments against physicalism are also arguments for the irreducible and hence immaterial nature of the mind and, given the existence of the material world, are thus arguments for dualism.
The knowledge argument asks us to imagine a future scientist who has lacked a certain sensory modality from birth, but who has acquired a perfect scientific understanding of how this modality operates in others. Suppose that Harpo, thanks to developments in neurosurgery, has an operation which finally enables him to hear. It is suggested that he will then learn something he did not know before, which can be expressed as what it is like to hear , or the qualitative or phenomenal nature of sound.
These qualitative features of experience are generally referred to as qualia. If Harpo learns something new, he did not know everything before. He knew all the physical facts before. So what he learns on coming to hear — the facts about the nature of experience or the nature of qualia — are non-physical. This establishes at least a state or property dualism.
See Jackson ; Robinson There are at least two lines of response to this popular but controversial argument. This essentially behaviouristic account is exactly what the intuition behind the argument is meant to overthrow. Such appeals to intuition are always, of course, open to denial by those who claim not to share the intuition. Some ability theorists seem to blur the distinction between knowing what something is like and knowing how to do something, by saying that the ability Harpo acquires is to imagine or remember the nature of sound.
In this case, what he acquires the ability to do involves the representation to himself of what the thing is like. But this conception of representing to oneself, especially in the form of imagination, seems sufficiently close to producing in oneself something very like a sensory experience that it only defers the problem: until one has a physicalist gloss on what constitutes such representations as those involved in conscious memory and imagination, no progress has been made. Rather, it is new way of grasping something that he already knew.
Demonstrative concepts pick something out without saying anything extra about it. Similarly, the scientific knowledge that Harpo originally possessed did not enable him to anticipate what it would be like to re-express some parts of that knowledge using the demonstrative concepts that only experience can give one. The knowledge, therefore, appears to be genuinely new, whereas only the mode of conceiving it is novel. Furthermore, experiencing does not seem to consist simply in exercising a particular kind of concept, demonstrative or not.
When Harpo has his new form of experience, he does not simply exercise a new concept; he also grasps something new — the phenomenal quality — with that concept. How decisive these considerations are, remains controversial.
I said above that predicate dualism might seem to have no ontological consequences, because it is concerned only with the different way things can be described within the contexts of the different sciences, not with any real difference in the things themselves. This, however, can be disputed. The argument from predicate to property dualism moves in two steps, both controversial.
The first claims that the irreducible special sciences, which are the sources of irreducible predicates, are not wholly objective in the way that physics is, but depend for their subject matter upon interest-relative perspectives on the world. This means that they, and the predicates special to them, depend on the existence of minds and mental states, for only minds have interest-relative perspectives. The second claim is that psychology — the science of the mental — is itself an irreducible special science, and so it, too, presupposes the existence of the mental.
Mental predicates therefore presuppose the mentality that creates them: mentality cannot consist simply in the applicability of the predicates themselves. First, let us consider the claim that the special sciences are not fully objective, but are interest-relative.
A mass of matter could be characterized as a hurricane, or as a collection of chemical elements, or as mass of sub-atomic particles, and there be only the one mass of matter. But such different explanatory frameworks seem to presuppose different perspectives on that subject matter.
This is where basic physics, and perhaps those sciences reducible to basic physics, differ from irreducible special sciences. On a realist construal, the completed physics cuts physical reality up at its ultimate joints: any special science which is nomically strictly reducible to physics also, in virtue of this reduction, it could be argued, cuts reality at its joints, but not at its minutest ones.
If scientific realism is true, a completed physics will tell one how the world is, independently of any special interest or concern: it is just how the world is. It would seem that, by contrast, a science which is not nomically reducible to physics does not take its legitimation from the underlying reality in this direct way. Rather, such a science is formed from the collaboration between, on the one hand, objective similarities in the world and, on the other, perspectives and interests of those who devise the science.
The concept of hurricane is brought to bear from the perspective of creatures concerned about the weather. Creatures totally indifferent to the weather would have no reason to take the real patterns of phenomena that hurricanes share as constituting a single kind of thing.
With the irreducible special sciences, there is an issue of salience , which involves a subjective component: a selection of phenomena with a certain teleology in mind is required before their structures or patterns are reified. The entities of metereology or biology are, in this respect, rather like Gestalt phenomena. Even accepting this, why might it be thought that the perspectivality of the special sciences leads to a genuine property dualism in the philosophy of mind?
It might seem to do so for the following reason. Having a perspective on the world, perceptual or intellectual, is a psychological state. So the irreducible special sciences presuppose the existence of mind. If one is to avoid an ontological dualism, the mind that has this perspective must be part of the physical reality on which it has its perspective. But psychology, it seems to be almost universally agreed, is one of those special sciences that is not reducible to physics, so if its subject matter is to be physical, it itself presupposes a perspective and, hence, the existence of a mind to see matter as psychological.
If this mind is physical and irreducible, it presupposes mind to see it as such. We seem to be in a vicious circle or regress. We can now understand the motivation for full-blown reduction.
A true basic physics represents the world as it is in itself, and if the special sciences were reducible, then the existence of their ontologies would make sense as expressions of the physical, not just as ways of seeing or interpreting it.
The irreducibility of the special sciences creates no problem for the dualist, who sees the explanatory endeavor of the physical sciences as something carried on from a perspective conceptually outside of the physical world. But psychology is one of the least likely of sciences to be reduced. If psychology cannot be reduced, this line of reasoning leads to real emergence for mental acts and hence to a real dualism for the properties those acts instantiate Robinson There is an argument, which has roots in Descartes Meditation VI , which is a modal argument for dualism.
One might put it as follows:. The rationale of the argument is a move from imaginability to real possibility. I include 2 because the notion of conceivability has one foot in the psychological camp, like imaginability, and one in the camp of pure logical possibility and therefore helps in the transition from one to the other.
See, for example, Chalmers , 94—9. This latter argument, if sound, would show that conscious states were something over and above physical states. It is a different argument because the hypothesis that the unaltered body could exist without the mind is not the same as the suggestion that the mind might continue to exist without the body, nor are they trivially equivalent. The zombie argument establishes only property dualism and a property dualist might think disembodied existence inconceivable — for example, if he thought the identity of a mind through time depended on its relation to a body e.
When philosophers generally believed in contingent identity, that move seemed to them invalid. But nowadays that inference is generally accepted and the issue concerns the relation between imaginability and possibility. No-one would nowadays identify the two except, perhaps, for certain quasi-realists and anti-realists , but the view that imaginability is a solid test for possibility has been strongly defended.
There seem to be good arguments that time-travel is incoherent, but every episode of Star-Trek or Doctor Who shows how one can imagine what it might be like were it possible. It is worth relating the appeal to possibility in this argument to that involved in the more modest, anti-physicalist, zombie argument. The possibility of this hypothesis is also challenged, but all that is necessary for a zombie to be possible is that all and only the things that the physical sciences say about the body be true of such a creature.
As the concepts involved in such sciences — e. There is no parallel clear, uncontroversial and regimented account of mental concepts as a whole that fails to invoke, explicitly or implicitly, physical e. For an analytical behaviourist the appeal to imaginability made in the argument fails, not because imagination is not a reliable guide to possibility, but because we cannot imagine such a thing, as it is a priori impossible.
The impossibility of disembodiment is rather like that of time travel, because it is demonstrable a priori, though only by arguments that are controversial. The argument can only get under way for those philosophers who accept that the issue cannot be settled a priori, so the possibility of the disembodiment that we can imagine is still prima facie open. A major rationale of those who think that imagination is not a safe indication of possibility, even when such possibility is not eliminable a priori, is that we can imagine that a posteriori necessities might be false — for example, that Hesperus might not be identical to Phosphorus.
But if Kripke is correct, that is not a real possibility. Another way of putting this point is that there are many epistemic possibilities which are imaginable because they are epistemic possibilities, but which are not real possibilities. Richard Swinburne , New Appendix C , whilst accepting this argument in general, has interesting reasons for thinking that it cannot apply in the mind-body case. In the case of our experience of ourselves this is not true. Now it is true that the essence of Hesperus cannot be discovered by a mere thought experiment.
That is because what makes Hesperus Hesperus is not the stereotype, but what underlies it. But it does not follow that no one can ever have access to the essence of a substance, but must always rely for identification on a fallible stereotype. One might think that for the person him or herself, while what makes that person that person underlies what is observable to others, it does not underlie what is experienceable by that person, but is given directly in their own self-awareness. This is a very appealing Cartesian intuition: my identity as the thinking thing that I am is revealed to me in consciousness, it is not something beyond the veil of consciousness.
Now it could be replied to this that though I do access myself as a conscious subject, so classifying myself is rather like considering myself qua cyclist. Just as I might never have been a cyclist, I might never have been conscious, if things had gone wrong in my very early life. I am the organism, the animal, which might not have developed to the point of consciousness, and that essence as animal is not revealed to me just by introspection. But there are vital differences between these cases.
A cyclist is explicitly presented as a human being or creature of some other animal species cycling: there is no temptation to think of a cyclist as a basic kind of thing in its own right. Consciousness is not presented as a property of something, but as the subject itself. Yet, even if we are not referring primarily to a substrate, but to what is revealed in consciousness, could it not still be the case that there is a necessity stronger than causal connecting this consciousness to something physical?
To consider this further we must investigate what the limits are of the possible analogy between cases of the water-H 2 O kind, and the mind-body relation. We start from the analogy between the water stereotype — how water presents itself — and how consciousness is given first-personally to the subject. It is plausible to claim that something like water could exist without being H 2 O, but hardly that it could exist without some underlying nature.
There is, however, no reason to deny that this underlying nature could be homogenous with its manifest nature: that is, it would seem to be possible that there is a world in which the water-like stuff is an element, as the ancients thought, and is water-like all the way down. The claim of the proponents of the dualist argument is that this latter kind of situation can be known to be true a priori in the case of the mind: that is, one can tell by introspection that it is not more-than-causally dependent on something of a radically different nature, such as a brain or body.
What grounds might one have for thinking that one could tell that a priori? The only general argument that seem to be available for this would be the principle that, for any two levels of discourse, A and B , they are more-than-causally connected only if one entails the other a priori. And the argument for accepting this principle would be that the relatively uncontroversial cases of a posteriori necessary connections are in fact cases in which one can argue a priori from facts about the microstructure to the manifest facts.
In the case of water, for example, it would be claimed that it follows a priori that if there were something with the properties attributed to H 2 O by chemistry on a micro level, then that thing would possess waterish properties on a macro level. What is established a posteriori is that it is in fact H 2 O that underlies and explains the waterish properties round here, not something else: the sufficiency of the base — were it to obtain — to explain the phenomena, can be deduced a priori from the supposed nature of the base.
This is, in effect, the argument that Chalmers uses to defend the zombie hypothesis. The suggestion is that the whole category of a posteriori more-than-causally necessary connections often identified as a separate category of metaphysical necessity comes to no more than this. If we accept that this is the correct account of a posteriori necessities, and also deny the analytically reductionist theories that would be necessary for a priori connections between mind and body, as conceived, for example, by the behaviourist or the functionalist, does it follow that we can tell a priori that consciousness is not more-than-causally dependent on the body?
Though we shall see later, in 5. The conceivability argument creates a prima facie case for thinking that mind has no more than causal ontological dependence on the body. Let us assume that one rejects analytical behaviourist or functionalist accounts of mental predicates. Then the above arguments show that any necessary dependence of mind on body does not follow the model that applies in other scientific cases. This does not show that there may not be other reasons for believing in such dependence, for so many of the concepts in the area are still contested.
For example, it might be argued that identity through time requires the kind of spatial existence that only body can give: or that the causal continuity required by a stream of consciousness cannot be a property of mere phenomena.
All these might be put forward as ways of filling out those aspects of our understanding of the self that are only obliquely, not transparently, presented in self-awareness. The dualist must respond to any claim as it arises: the conceivability argument does not pre-empt them. All the arguments so far in this section have been either arguments for property dualism only, or neutral between property and substance dualism.
In this subsection, and in section 4. The ones in this section can be regarded as preliminaries to that in 4. He famously expresses his theory as follows. Nevertheless, in the Appendix of the same work he expressed dissatisfaction with this account. Somewhat surprisingly, it is not very clear just what his worry was, but it is expressed as follows:. This Berkeleian view is expressed in more modern terms by John Foster. There is a clash of intuitions here between which it is difficult to arbitrate.
There is an argument that is meant to favour the need for a subject, as claimed by Berkeley and Foster. To say that, according to the bundle theory, the identity conditions of individual mental states must be independent of the identity of the person who possesses them, is to say that their identity is independent of the bundle to which they belong.
Perhaps the identity of a mental event is bound up with the complex to which it belongs. That this is impossible certainly needs further argument. Hume seems, however, in the main text to unconsciously make a concession to the opposing view, namely the view that there must be something more than the items in the bundle to make up a mind. He says:. Talk of the mind as a theatre is, of course, normally associated with the Cartesian picture, and the invocation of any necessary medium, arena or even a field hypostasize some kind of entity which binds the different contents together and without which they would not be a single mind.
Modern Humeans — such as Parfit ; or Dainton — replace the theatre with a co-consciousness relation. So the bundle theorist is perhaps not as restricted as Hume thought. The bundle consists of the objects of awareness and the co-consciousness relation or relations that hold between them , and I think that the modern bundle theorist would want to say that it is the nexus of co-consciousness relations that constitutes our sense of the subject and of the act of awareness of the object.
The Humean point then becomes that we mistake the nexus of relations for a kind of entity, in a way similar to that in which, Hume claims,we mistake the regular succession of similar impressions for an entity called an enduring physical object. Whether this really makes sense in the end is another matter. I think that it is dubious whether it can accommodate the subject as agent , but it does mean that simple introspection probably cannot refute a sophisticated bundle theory in the way that Lowe and Foster want.
The rejection of bundle dualism, therefore, requires more than an appeal to our intuitive awareness of ourselves as subjects. We will see in the next section how arguments that defend the simplicity of the self attempt to undercut the bundle theory.
There is a long tradition, dating at least from Reid , for arguing that the identity of persons over time is not a matter of convention or degree in the way that the identity of other complex substances is and that this shows that the self is a different kind of entity from any physical body.
Criticism of these arguments and of the intuitions on which they rest, running from Hume to Parfit , have left us with an inconclusive clash of intuitions. The argument under consideration and which, possibly, has its first statement in Madell , does not concern identity through time, but the consequences for identity of certain counterfactuals concerning origin.
It can, perhaps, therefore, break the stalemate which faces the debate over diachronic identity. The claim is that the broadly conventionalist ways which are used to deal with problem cases through time for both persons and material objects, and which can also be employed in cases of counterfactuals concerning origin for bodies, cannot be used for similar counterfactuals concerning persons or minds. Concerning ordinary physical objects, it is easy to imagine counterfactual cases where questions of identity become problematic.
Take the example of a particular table. We can scale counterfactual suggestions as follows:. The first suggestion would normally be rejected as clearly false, but there will come a point along the spectrum illustrated by i and iii and towards iii where the question of whether the hypothesised table would be the same as the one that actually exists have no obvious answer.
There will thus be a penumbra of counterfactual cases where the question of whether two things would be the same is not a matter of fact. Let us now apply this thought to conscious subjects. Suppose that a given human individual had had origins different from those which he in fact had such that whether that difference affected who he was was not obvious to intuition. What would count as such a case might be a matter of controversy, but there must be one.
Some philosophers might regard it as obvious that sameness of sperm is essential to the identity of a human body and to personal identity. In that case imagine a counterpart sperm in which some of the molecules in the sperm are different; would that be the same sperm?
If one pursues the matter far enough there will be indeterminacy which will infect that of the resulting body. There must therefore be some difference such that neither natural language nor intuition tells us whether the difference alters the identity of the human body; a point, that is, where the question of whether we have the same body is not a matter of fact. How one is to describe these cases is, in some respects, a matter of controversy.
Some philosophers think one can talk of vague identity or partial identity. Others think that such expressions are nonsensical. There is no space to discuss this issue here. It is enough to assume, however, that questions of how one is allowed to use the concept of identity effect only the care with which one should characterize these cases, not any substantive matter of fact.
If there were, then there would have to be a haecceitas or thisness belonging to and individuating each complex physical object, and this I am assuming to be implausible if not unintelligible. More about the conditions under which haecceitas can make sense will be found below. One might plausibly claim that no similar overlap of constitution can be applied to the counterfactual identity of minds.
Why is this so? Can we say, as we would for an object with no consciousness, that the story something the same, something different is the whole story: that overlap of constitution is all there is to it?
For the Jones body as such, this approach would do as well as for any other physical object. The creature who would have existed would have had a kind of overlap of psychic constitution with me. The third answer parallels the response we would give in the case of bodies. But as an account of the subjective situation, it is arguable that this makes no sense. Clearly, the notion of overlap of numerically identical psychic parts cannot be applied in the way that overlap of actual bodily part constitution quite unproblematically can.
This might make one try the second answer. It is difficult to see why it does not. Suppose Jones found out that he had originally been one of twins, in the sense that the zygote from which he developed had divided, but that the other half had died soon afterwards. He can entertain the thought that if it had been his half that had died, he would never have existed as a conscious being, though someone would whose life, both inner and outer, might have been very similar to his.
He might feel rather guiltily grateful that it was the other half that died. It would be strange to think that Jones is wrong to think that there is a matter of fact about this. If the reasoning above is correct, one is left with only the first option. If so, there has to be an absolute matter of fact from the subjective point of view. But the physical examples we have considered show that when something is essentially complex, this cannot be the case.
When there is constitution, degree and overlap of constitution are inevitably possible. So the mind must be simple, and this is possible only if it is something like a Cartesian substance.
His worries concerned the cramping effect that matter would have on the range of objects that intellect could accommodate. Parallel modern concerns centre on the restriction that matter would impose on the range of rational processes that we could exhibit.
Some of these concerns are of a technical kind. But there are other less technical and easier to appreciate issues. I will mention four ways in which physicalist theories of thought seem vulnerable to attack by the dualist.
There has been a rise or revival of a belief in what is now called cognitive phenomenology , that is, the belief that thoughts, of whatever kind — beliefs, desires, and the whole range of propositional attitude state — are conscious in a more than behavioural functional sense.
The issue is whether, under this constraint, one can give an account for meaningful communication and understanding at all. This is clearly expounded in Dennett ; see also the entry on the frame problem. Numbers, it would seem, are abstract objects, yet our intellects operate with them all the time. How does a physical brain interact with an abstract entity? A similar problem could be raised for concepts in general; they are abstract, general entities, not physical particulars, yet they are the meat and drink of thinking.
For a dualist about intellect there does not appear to be the same problem. The immaterial intellect is precisely the sort of thing that can grasp abstract objects, such as numbers and universals — in the Aristotelian context, the immaterial intellect is the home of forms.
There is still the issue of how this intellectual capacity of the immaterial mind relates to sensory consciousness. According to Aristotle, perception is a wholly embodied process, but for modern dualists, sensory consciousness is not material.
In order to unify the perceptual and intellectual functions of the mind, traditional empiricists tended to be imagists, in their theory of thought, in order to assimilate the intellectual to the sensory, but this assimilation is rejected by those who believe in a distinct cognitive phenomenology, as mentioned in a above.
The issue of how these two functions of mind are related in dualism is, it seems to me, insufficiently investigated. Armstrong in his is a striking exception to this, accepting an in re theory of universals. I will not discuss a further, as it is discussed in section 5 of the entry on phenomenal intentionality , An immaterialist response to d can be found in Robinson Both b and c seem to draw out the claim that a material system lacks understanding.
Searle imagines himself in a room with a letter box through which strings of symbols are posted in, and, following a book of rules, he puts out symbols which the rules dictate, given the strings he is receiving. In fact, Searle says, he has been conducting a conversation in Chinese, because the symbols are Chinese script, and the rules those on which a Chinese computer might work, but he has not understood a word.
Therefore neither does a computer understand, so we, understanding creatures, are not computers. A blow was struck against the computational theory of thought when, in , Fodor produced his The Mind Does Not Work That Way , in which he made clear his belief that the kind of computationalism that he had been describing and developing ever since the s only fits sub-personal informational processing, not conscious, problem solving thought.
One physicalist response to these challenges is to say that they apply only to the classical computing model, and are avoided by connectionist theories.
Classical computing works on rules of inference like those of standard logic, but connectionism is rather a form of associationism, which is supposedly closer to the way in which the brain works. See the entry on Connectionism. But Gary Marcus — see Other Internet Resources and others have pointed out the ways in which these impressive machines are quite different from human thought.
We can learn things with very few trials because we latch on to abstract relationships, whereas the machine requires many — perhaps thousands or millions — of examples to try to catch extensionally what we get by the abstract or intensional relation.
The dualist might sum up the situation on thought in the following way. The case against physicalist theories of sensation is that it is unbelievable that what it feels like to be struck hard on the nose is itself either just a case of being disposed or caused to engage in certain behaviours, or that what it feels like is not fundamental to the way you do react.
Similarly, the dualist about thought will say, when you are, for example, engaged in a philosophical discussion, and you make a response to your interlocutor, it is obvious that you are intending to respond to what you thought he or she meant and are concentrating on what what you intend to say means.
It seems as bizarre to say that this is a bye-product of processes to which meaning is irrelevant, as it is to claim the same about sensory consciousness. You are, in other words, as fundamentally a semantically driven engine, as you are a sensorily consciously driven one.
Adam and Eve are explicitly ejected from Eden before eating of the tree of immortality. In contrast, Sumerian, Mesopotamian, Egyptian and Greek myths do explicitly reference and often center around an afterlife.
However, when Mesopotamian, Egyptian and Greeks enter this afterlife, it is as a body, as a person: Gilgamesh and Odysseus and Hercules journey to the underworld as a man or, we might say, a god-man where Gilgamesh also learns that only gods can have immortality, and where Odysseus sees "shades" of the physical forms of his friends and families; the Egyptian buried the pharaohs with items necessary to continue a physical life in the afterworld, etc.
Translation Issues , Again: The Septuagint. The most extreme cases happen when we dream or hallucinate, but this also occurs when we confuse one object for another. Plato showed that we are often presented with illusions of this kind. Things are not always what they seem, and we are not always aware that we are making these mistakes.
To find true knowledge, we need to examine our own minds in what's known as 'rational introspection'. Plato praised mathematics as one of the only forms of true knowledge. He disliked art because he thought that we distort our perception even further when we attempt to copy an imperfect image.
This is analogous to a philosopher who is not believed when they claim to see the world as it truly is. Plato thought that the things we perceive on Earth are really composed of ideas or forms.
A form is an eternal and perfect concept, something that is strived for but never actualised on Earth. Forms also apply to abstract concepts like beauty.
He claimed that all of the forms exist outside of the realm of regular perception, in the 'realm of the forms'. Plato set up an academy for philosophy, and one of its pupils was Aristotle, who was born in BCE. In the 17th century, Thomas Hobbes argued that we can only form ideas of physical things. This means that if we do have a soul, we cannot become aware of its presence. Hobbes claimed that,. He suggested that the soul may be the only thing we can be aware of. Descartes was a rationalist like Plato.
He argued that true knowledge is only gained through rational introspection and that the senses cannot be trusted. Descartes was also a mind-body dualist; because he could conceive of his mind existing without his body, he concluded that the mind must be made of an entirely different substance. In Meditations on First Philosophy , first published in , Descartes suggested that the mind differs from physical substances in three ways:.
Any physical theory of the mind will have to solve these four problems. Descartes believed that phenomenal qualities, like colours and sounds, must be made of a different substance to physical matter because they do not exist within our scientific description of the world.
Figure Colour could be replaced by any of our sensory experiences to illustrate this problem: sound is a physically indescribable representation of the vibrations of air molecules, touch and pain represent signals sent from nerve cells, and taste and smell represent the experiences of different chemical reactions. These sensory experiences, as well as other subjective internal experiences like emotions, are described as qualia.
Qualia are defined by the fact that you cannot know what they are like without experiencing them for yourself, and you cannot compare qualia with other people. This is evident from the fact that someone cannot imagine a colour they have never seen, even if they have a complete understanding of the physics of light:. Descartes chose the former and argued that common sense realism, the view that we are directly equated with physical objects, is false.
This can happen when we dream or imagine, for example. Descartes claimed that the same is true of emotional responses and even pain, using the phenomenon of phantom limbs as an example of pain that does not correspond to the physical body.
Descartes claimed the dream argument shows that knowledge comes from rational introspection. He stated that,. Descartes illustrated the difference between introspection and the imagination with the following example,.
Like Plato, Descartes believed that mathematical concepts contain an element of truth that goes beyond what we are capable of imagining. Despite the conclusions of the dream argument, Descartes went on to claim that rational introspection could also be flawed. To demonstrate this, he invoked the idea of an all-powerful God and asked,. Descartes realised that the only thing he could be certain of was his own existence.
Although he could be tricked into thinking anything, he could not be tricked into doubting that he is thinking at all, and since there are thoughts, there must be existence. I shall consider myself as having no hands or eyes, or flesh, or blood or senses, but as having falsely believed that I had all these things. This will be hard work, though, and a kind of laziness pulls me back into my old ways. Like a prisoner who dreams that [they are] free, starts to suspect that it is merely a dream, and wants to go on dreaming rather than waking up.
Descartes used the problem of qualia to show that the mind must be composed of a different substance to physical matter. He also claimed that the mind differs from physical substances because it does not exist in space. He believed this to be evident from the fact that he could imagine his mind existing without the need for a body.
So it is certain that I am really distinct from my body and can exist without it.
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