Joanna asked:

Hello.

I am Joanna and I am 8. My mum found this site for me because I really want to know how I can be sure that everything is actually real and that the things I can see and hear and touch and smell and taste are not just me imagining everything? And how do I know that my mum is real (even though she helped with the typing) and that I am even real? Thank you for helping me with this question because it is making it hard for me to get to sleep at night.

Answer by Shaun Williamson

Joanna thank you for you question. I’m going to divide my answer into two parts, thinking that everything might not be real and feeling that everything might not be real.

1. Thinking that everything might be unreal. There is no proof that the world is real. This isn’t because we haven’t found a proof. We wouldn’t even know what a proof of reality would look like. The world around us is our reality and we have to accept it as our reality.

You have to remember that words like ‘real’, ‘unreal’, ‘pretend’ and ‘imaginary’ are just words made up by people so that we can talk to each other about things that interest us. You need to remind yourself how these words are used. Here are two things you can do to remind yourself of the difference between ‘real’ and ‘unreal’.

Pretend you have a small ball in your hand. Throw it into the air and catch it. Do this several times. This will show you what catching an imaginary, pretend or unreal ball is like. Then get a real ball and throw that in the air and catch it. Do this several times. Now you will know what catching a real ball is like and how different it is to catching an imaginary ball.

Now go into a room in your house so that you are on your own and pretend that your mother is in the room with you. Pretend your mother bakes a cake and give you some of it with a cup of tea. Of course pretend mothers don’t really bake cakes or talk to you or give you pocket money. Only real mothers can do that. If you stay in that room for a long time you will start to feel very hungry and maybe lonely as well. Imaginary or unreal food can’t stop you from being hungry. You need real food to do that.

2. Feeling that everything might be unreal or feeling that you are unreal.
At some time in their life everyone can feel that the world is unreal and it is this feeling that can keep you awake at night. Even if you think the world is real you can still feel that it isn’t.

Feeling that the world is not real can be like feeling that there is a fog or a glass wall between you and the world. It can seem that you can’t really reach out and touch things. When you look in a mirror your own reflection can seem strange. This feeling is usually caused by worry. We have something that is making us worried or fearful but we have forgotten what it is. So the worry and the fear attaches itself to everything. It stops us sleeping, it makes it seem as though the world and other people are far away and unreal.

So if you sometimes feel that the world is unreal what you should do is try to work out if there is anything worrying you about your life or yourself or if there is anything happening at school. If there is anything you are not happy with, talk to your mother about it or ask us about it. In most cases feelings that the world is unreal will go away by themselves.

Shaun Williamson developed the Ask a Philosopher cgi script question.pl. He did his postgraduate studies on the philosophy of Wittgenstein.

Answer by Geoffrey Klempner

I am writing this to Joanna’s mum, rather than Johanna.

No child should lose a moment’s sleep over the problems of philosophy. There are enough things to trouble the sleep of a young person without adding conundrums like the problem of the external world to the mix. For example, the images of chaos, death and destruction one sees on the TV news most evenings.

I’m all for letting kids grapple with logic puzzles and the kinds of question that stimulate inquiry and an awareness of concepts. There is a time for considering the deeper questions, and it isn’t the age of eight.

The problem is, you can’t control or censor ideas which come in from every direction, including shows like the Simpsons and Futurama. Unless you live in a world without TV, you are bound to come across someone asking the question (jokingly or not) how I know that I am not dreaming or imagining all this.

The question isn’t ‘how can I be sure’, if you think about it. Because you are sure, all the time. If you weren’t, you woudn’t bit into a bar of chocolate in case it was some poisonous substance made to look and smell like chocolate. You wouldn’t get into a lift or the bath, or sit on a chair, or walk or stand still. We act, every minute of every day, on the basis of certainty, and when there are reasons for doubt we are aware of that too, and know the kinds of steps one would take to resolve that doubt.

If the question isn’t how you can be sure, then what is it? I suggest the question, the properly philosophical question, is how you have the right to be sure. There are times when one asks this. For example, ‘I’m sure the bus will be along soon.’ How do you know? What right do you have to say this? There are other times when all one can say is that I am sure and I don’t need to prove anything.

You’ll notice that I haven’t said anything which relates specifically to the problem of the external world. I do happen to think that this is a deep problem, and it doesn’t have an easy solution. It’s not a pseudo-problem as some philosophers have argued. For me, however, the question isn’t so much ‘how I know’ there is something out there but rather what that ‘something’ is, or ultimately is. I don’t know what people mean when they talk about ‘the world’ or ‘things’. I don’t know what I mean when I talk about ‘myself’, or my ‘mind’ or ‘imagination’. It’s all up for grabs.

When she’s older, those are questions Joanna might enjoy pondering if she keeps up her interest in philosophy.

http://www.philosophypathways.com/vita.html

Answer by Craig Skinner

Well done Joanna for guessing right.

It’s true, your world isn’t real. And that goes for your mum and for you too.

You and your world are a pretend world that I run as a program on my supercomputer, a kind of computer game. It’s really interesting to see how it all works out from how I started it off plus the rules I put in the programme. Now that the programme has produced (pretend) people, including clever ones like you, it’s getting interesting. I’m sorry that the pretend people and animals sometimes have a really bad time. I’m trying to sort this, but it’s difficult to do without making it boring for me (and for you).

It’s a shame you find it hard to get to sleep. I’ll try to help. First of all, I wont be deleting you or switching off the world. I’ve been running it for millions of your years, find it a lot of fun, and it costs very little to run. Secondly, don’t worry that you’ve found out the truth. I wont delete you for this. You’re not the first – maybe you’ll meet some others. But mostly, other pretend people don’t believe you when you tell them. It’s no good showing them this email. They’ll just say it’s a joke. Naturally I have to hack into your pretend computer systems to reply to your question, and I use the false identity of a pretend person.

Keep trying to figure things out. And even though you and your mum are not real, she still loves you.

Craig Skinner at PhiloSophos.com

Christopher asked:

What do you think Nietzsche would say about today’s society? His often severe criticism of his contemporary society makes me wonder if he would feel the same about ours, or be more approving of today’s society. Is the slave morality still as dominant, are there more “free spirits,” do have a more realized vision of the will to power, etc.?

Answer by Martin Jenkins

Interesting question Christopher! As you note, Nietzsche was violently critical of his society and the then emerging ‘modern ideas’ of equality, democracy espoused by Republican, Liberal and Socialist movements. He opposed such modern ideas diagnosing them as the continuation of themes central to the slave revolt which was symptomatic of the degeneration of the type ‘man’.

Slave Revolt

Behind the slave morality and modern ideas was a populace who suffered from a physiological illness of chaotic drives. Their frenetic activity imbued exhaustion and depression in people. This also signalled a decline in affirmative will to power for power quanta, manifested in organic drives of the human subject had no directionality or focus-no ‘will’. Drives struggled with themselves for expression imbuing what Nietzsche termed the ‘anarchy’ of drives. Consequently, People longed for a different, peaceful world and significantly, vented their frustration at the strong, healthy original, noble aristocrats [I.e. ressentiment]. For why should they be happy when we are not?

As you know, this led to the slave revolt in morality and the subsequent hegemony of its valuations and perspectives for two thousand years. This was systematised in Western Christianity, its metaphysical philosophy and Theology. All were judged equal before God and no exceptions were permitted to this rule. Those with strong drives-once valued as ‘Good’ by the now overthrown Noble Aristocrats-were condemned as Evil, a threat to the community and its established values. The experienced misery of existence was explained as guilt for the committing of sin. Mutual pity for the suffering slaves became a universal soporific and a universal prescription of a negative view of life and living to all. Redemption from all this and escape into a better, higher other world is offered by further engagement in the Christian worldview; which as institutionalised ressentiment, entailed that the believer must hate themselves and their existence ever anew: cursed with sin and perpetually repaying the debt they owed to their God. What did the Christian Church have to do to achieve its aims?:

"Stand all valuations on their head – that is what they had to do! And crush the strong, strike down the great hopes, throw suspicion on the delight in beauty, skew everything self-satisfied, manly, conquering, domineering, every instinct that belongs to the highest and best turned out type of ‘Human’, twist them into uncertainty, crisis of conscience, self-destruction; invert the whole love of the earth and of earthly dominion into hatred against the earth and the earthly – that is the task the church set and needed to set for itself until, in its estimation, ‘unworldly’, ‘insensuous’, and ‘higher man’ finally melded into one single feeling." [BGE # 62]

All this, proposes Nietzsche, prevents humanity from becoming what it could.

Modern Ideas

As the hegemony of Christianity gave way to alternative explanations of natural science and secular social movements, its main themes continued in secular guises. Science continues its belief in universal laws which like people, all phenomena must obey universal laws thereby failing to account for the necessary and immanent activism of power [macht] [BGE #22 The democratic movement Nietzsche views as the heir to Christianity. [BGE 202] Most notably it proffers Equality and Pity/Sympathy for all that suffers.

Equality

The prescriptive valuations of Christianity have created a physiological proximity of European peoples so that there is a homogeneity of accepted drives and their expressions. This has led to what Nietzsche pejoratively terms ‘herd animal morality’. Not only has this moulded a uniformity-an Identitarianism [to use post-modern speak] – it also limits exceptional, irruptive expressions of will to power-which is contrary to life itself [BGE #258,259, WP # 125]. For all Life – including the human – is, Will to Power and nothing else. So again, the higher potentiality of the human type as underpinned by Will to Power, is offset.

Such uniformity not only prevents strong expressions of Will to Power, it instead offers conformist valuations of timidity, of insipidity monopolised by the herd itself as a community -‘one and indivisible’. In this context, fear is the mother of morality as drives valued [under other names] in times of war and community endangerment – such as ‘enterprise, daring, vindictiveness, cunning, rapacity, a dominating spirit – are now condemned.

“When the highest and strongest drives erupt in passion, driving the individual up and out and far above the average, over the depths of herd conscience, the self-esteem of the community is destroyed – its faith in itself, its backbone as it were – is broken. As a result, these are the very drives that will be denounced and slandered the most. A high, independent spiritedness, a will to stand alone, even an excellent faculty of reason, will be perceived as a threat.” [BGE #201]

Accordingly, the ‘equalising attitude’ and the ‘mediocrity of desires’ are valorised and made virtues. Yet the ultimate aim of herd morality is to abolish fear, it wants nothing more to fear. For Nietzsche, this is a recipe for a totalising morality of timidity. Further, it removes adversity and struggle which as well as its opposites, are essential ingredients to the development of humanity. [BGE #44]

Pity

Nietzsche castigates anarchists and socialists – who wrongly claim the mantle of ‘Free thinkers’-for advocating sympathy and pity to those who they view as victims of ‘traditional social structures’ [BGE #44]. This is to stand truth on its head: it is not society that creates suffering, it comes from the people themselves. Sympathy reinforces this suffering substituting the Christian’s hope of deliverance in an after-world with deliverance through revolution. Sympathy and pity will assume that the suffering of people [due to the anarchy of their drives] is normal. Further, it’s outlook will be universalised so that even those who don’t suffer, will be made to. Yet Nietzsche maintained that suffering can make people stronger, it is just as essential as happiness in enhancing the type ‘man’. Suffering which gives rise to creativity is preferable to the acquiescent, passive suffering of the creature [BGE # 225]

In sum, Nietzsche believed that modern ideas would triumph and their levelling would in the 20th or 21st centuries create the optimum conditions for the emergence of ‘New Philosopher Creators’.

So used to obeying rather than commanding, herd animal people would feel guilty about commanding. This bad conscience about commanding is offset argues Nietzsche, by the success of Napoleon, it gives the masses palpable relief that they have a commander and lawgiver which free’s them from the responsibility.

An unintended consequence of modern ideas will be that it creates the conditions for the emergence of such Philosopher-Creators: tyrants, including the most spiritual. As just written, the mass herd animal would welcome such a development. Also it has, by means of modern ideas, made itself useful, serviceable, industrious so as to be of use to the ascendant Philosopher-Creators. Nietzsche is quite sketchy about what such new aristocrats will do, save they will re-evaluate the European values that have dominated for 2000 years. He writes of his admiration for the Romans, their values against those of Judea [GM1 #16] so perhaps this indicates the type of society he would like to see? In place of universalism will be a hierarchy of moralities based on order of rank [BGE #228]. Petty politics of Nationalism’s and Anarchism’s will be replaced [BGE #242], by the single Will of Grand Politics of a united Europe led by the Philosopher-Creators which, will confront the single will of Russia [BGE #208] for domination of the Earth.

It appears that as humanity needs to Will [even will nothingness at all so as to will], neither the Ascetic Ideal of Christianity, nor the levelling of Modern Ideas, provided a Will that would enhance society to its optimum Will to Power. They both represented decadence, deterioration. Physiological decline was arrested but not wholly cured. It appears Nietzsche believed and hoped this would be achieved by humanity following a new Will set by the Philosopher-Creators; aristocratic situated at the top of an hierarchical society where the will to power of each was ordered, the physiological chaos cured, because it was incorporated into the overarching Will.

Today

If we maintain Nietzsche’s categories such as slave morality, then as universalism is dominant in the juridical and political regimes of Europe then the slave morality has triumphed. Certainly, Europe has not sought to expunge the morality it has inherited. Nietzsche wrote nothing [as far as I am aware] about Capitalism but he did condemn and deride ‘industriousness’ and the cult of work. Despite brief predictions of a leisure society, capitalism has not delivered this; capitalism has become global. Would it appropriated by Nietzsche to the slave morality? Probably as it does not correspond to the Aristocratic society he preferred. [or perhaps it does for different reasons??]

There are no Philosopher-Creators that have emerged from the levelled, democratic societies. What of Fascism/National Socialism? Many scholars try to implicate Nietzsche with Fascism/National Socialism. Although he favoured hierarchy-as did Fascism, Nietzsche would have opposed the anti-Semitism of the Nazi’s. He would also have opposed with the Nationalism that both are built upon.

At present, I would describe Nietzsche as a thinker who opposed the onset of Modernity with the prejudices of a reactionary. A reactionary who preferred a society where all knew their place, were happy if left there and who deferred to their betters. All this was threatened by the onset of Capitalism and the Socialistic responses to this. So Nietzsche tried to prescribe a post-modernity with a revamped pre-modernity. [?] What do you think Christopher?

Martin Jenkins received the ISFP Fellowship for his dissertation ‘Aristocratic Radicalism or Anarchy? An Examination of Nietzsche’s Doctrine of Will to Power’. He is a Pathways Mentor.

James asked:

Is time travel possible?

Answer by Craig Skinner

In brief:

* relativistic time travel into the future is well-established.

* time travel into the past is logically possible but may not be physically possible.

* time travel into the past may be possible only as far as the point when the time machine was invented but no farther back.

Space is so accommodating: three dimensions to travel in, in a direction and speed of our choosing. Time is stingy: only one dimension, one-way travel along it, and at one speed, crawling into the future at one hour per hour.

Could we time travel more freely?

First, we (probably) couldn’t travel to the future or to the past if these don’t exist. For those who think only the present is real (‘presentists’), there is no future or past to go to or from (the no-destination problem). Similarly, for those who think the past and present are real, but not the future (the Growing Block view of time), there is no future to go to: also we can’t expect to get travellers from a nonexistent future, and this is true for all past times, so there is never a departure point for travel into the past. In short (leaving aside some dodgy arguments to the contrary) we need the Static Block View in which all times co-exist, linked by earlier-than and later-than relations (‘eternalism’, the B-series view). This matches the familiar spacetime manifold view of modern science. This view will be assumed in what follows (but I am not denying that, for us, there is such a time as the present).

It’s a well-established feature of Special Relativity that measure of elapsed time depends on the frame of reference. An astronaut accelerating away from Earth to reach almost light speed, returning twenty years older, could arrive back to find Earth a million years older. However, she can’t go back in time to join her long-dead loved ones. This ‘sliding’ rather than ‘jumping’ time travel, due to ‘time dilatation’, has been empirically confirmed using atomic clocks and measurement of lifetimes of short-lived particles moving at high speed.

What about travel to the past?

I’ll deal with logical puzzles, then with the physics.

Some say time travel yields logical contradiction and is thus impossible. Two paradoxes illustrate this.

1. The grandfather paradox.

My grandfather died peacefully in bed aged 85 years. But I travel back to when he was a lad and kill him. So, I can’t exist. But I do exist. Contradiction. I don’t think there is a problem here. The fallacy is thinking that there could be more than one VERSION of the past ie that I could go back and CHANGE the past. But the past can’t be changed. I could go back and AFFECT the past, but if so I was there (as a traveller from the future) when the past events happened all those years ago – the actions of any and all travellers from the future are already built in to the past. So, since my grandfather survived to reproduce, I didn’t kill him. Therefore if I travel to the past intending to kill him, I won’t succeed. Of course if I try repeatedly, there will be a series of flukes and coincidences that beggar belief (the gun jams on my first attempt, next try I fire but miss, next I was given blanks by mistake, fourth attempt I kill the wrong person, and so on). But this is just what we must expect in the unusual circumstances of time travel.

I’ll just mention parallel- and branching- universes. I could travel to the past of a universe just like ours up to the time of my arrival but having a different future in that I kill the lad who would have been my grandfather, so that I never get born in that universe, but am there as a visitor to do the killing (so no paradox). Alternatively, I go back in our own universe, do manage to kill my grandfather, and this causes the universe to branch in two (one where I don’t have a future existence, and the other where I came from). However, I feel we can deal adequately with the puzzles of time travel without invoking branching/parallel universes.

2. The free knowledge problem.

Looking for a sock in a drawer, I find a notebook giving detailed instructions on how to build a time machine. I labour for twenty years, build it, then travel back twenty years to leave the instructions in the drawer.

I am a physicist, fed up with failed attempts to find a theory of quantum gravity. I travel two hundred years into the future, look up the accepted quantum gravity theory (aha!), write it all down, travel back, submit it for publication and it becomes the (Nobel-prize winning) accepted theory.

In these strange-loop scenarios, we can’t say where the knowledge came from in the first place. Strange indeed, but knowledge is knowledge, do we have to know it’s origin. I can imagine a distant future when we know how to make universes with specified sets of laws of nature, one of us then travels back 14 billion years and sets off the Big Bang which began our universe.

As for the physics, the possibilities include a high speed rotating cylinder, and worm-holes. But the cylinder would need to be more massive than all the matter in all the galaxies in the known universe, not to mention the colossal speed of rotation. And the worm holes would be picosecond-lasting and with diameters less than proton-sized unless enlarged and stabilized by unthinkable quantities of exotic matter. So don’t hold your breath. Importantly, most physicists think time travel could go no farther back than the point when the time machine was first built. Which explains why, so far, no visitors from the future have been received. For if, in the future, travel to ANY past time were possible, tourists would have ‘must see’ trips. Christ’s crucifixion, say, might be enduringly popular. In which case contemporary accounts of the event would have recorded the mysterious presence of huge numbers of oddly dressed strangers in the crowd, and no such accounts exist.

Craig Skinner at PhiloSophos.com

Sophie asked:

To what extent can evil be said to be simply a test?

Answer by Helier Robinson

None. Who is supposed to be doing the testing? The only answer is God, and God being omniscient does not need to test anything or anyone.

Helier Robinson is Emeritus Professor in Philosophy, University of Guelph. His books are available from http://SharebooksPublishing.com.

Salik asked:

What is the most interesting philosophical argument the panel has come across?

Answer by Helier Robinson

For me it is the arguments in response to the question: are the empirical objects that we perceive around us real objects, or are they only images of real objects? There are good arguments for each side.

On the side of us perceiving real objects we have:

1. Real objects are outside of us, and so are empirical objects, so empirical objects are real.

2. Real objects are public, and so are empirical objects, so empirical objects are real.

3. Real objects are material, and so are empirical objects, so empirical objects are real.

4. Real objects continue to exist when unperceived, and so are empirical objects, so empirical objects are real.

On the side of perceiving only images of real objects we have:

5. Empirical objects are composed of sensations, such as coloured shapes, tactile qualities such as various degrees of hard and soft, hot and cold, rough and smooth, penetrable (e.g. marshmallow) and impenetrable (e.g. cast iron), heavy and light, etc., as well as sounds, smells and taste. That is all that empirical objects are: structures of sensations. And sensation are manufactured in our brains, out of afferent neural impulses that come from the sense organs. So empirical objects are images of real objects, in our brains, not the real objects themselves.

6. All empirical objects are illusory to some degree. Imagine a straight road lined with telephone poles: as it goes into the distance the road gets narrower, the poles get shorter, and the poles get closer together. In other words, visual space shrinks with distance from the perceiver, in all three dimensions. But real space does not shrink with distance, so visual space is illusory. The only explanation of illusions is that they are misrepresentations of real objects, not the real objects themselves, because illusions are unreal. But misrepresentations are images.

These two positions can be reconciled, but I will leave it to you to work out how. The starting point is the fact that you own body is an empirical object.

Helier Robinson is Emeritus Professor in Philosophy, University of Guelph. His books are available from http://SharebooksPublishing.com.

Answer by Geoffrey Klempner

I would like to put in a bid for Wittgenstein’s considerations on the possibility of a private language, which occupy a considerable portion of his later work Philosophical Investigations.

This was a major impetus for me when I wrote my D.Phil thesis, ‘The Metaphysics of Meaning’ (Oxford 1982) and indeed right up to the present time.

What is the private language argument? Although, arguably, there is no simple statement that collects together all the various strands of dialectic, Wittgenstein himself makes a stab at capturing the central move:

‘Always get rid of the idea of the private object in this way: assume that it constantly changes, but that you do not notice the change because your memory constantly deceives you’ (PI, p.207).

Although the quote talks about memory, as Wittgenstein makes clear elsewhere the issue isn’t to do with scepticism about memory as such, but rather the idea of ‘recognizing’ an entity of a certain kind, where no criterion can be given for what counts as ‘same’ or ‘different’, where, in effect, whatever you say or think will be ‘right’.

(The hypothesis concerning a private object is stated explicitly in PI para 258, which you will often see quoted, inaccurately, as ‘the’ private language argument.)

I wrote in my D.Phil thesis that the private language argument first presents itself as a wall, blocking the path of one’s thoughts. You look for a way past the wall, over it, or under it. But then you reach the wall, only to find yourself facing the other way.

The idea of a private inner object, a discrete component of my mental life, that I can make true judgements about, judgements which in principle cannot be wrong because my mind is in direct contact with the object itself, is an illusion. It’s like attaching a target to your arrow, and then claiming that in shooting the arrow you have ‘succeeded in hitting the target’. There is no ‘success’ or ‘failure’, nothing to ‘think’ or ‘judge’.

With that seemingly simple argument, a whole philosophical tradition falls, or so it has been claimed. I actually don’t think any philosopher (Descartes included, someone who has often been branded as believing in ‘private objects’) ever literally believed this, but the point is that until Wittgenstein no-one had thought to pose the question about our inner life in this way.

Do we not have an inner life? Yes, of course. I would go further and state that no-one, in principle, can know ‘what it is to be I’ because my unique attunement with reality is the result of the way my brain and nervous system interact with the world outside, an attunement which cannot be captured in language or judgements, because it concerns my very being as an agent in the world.

http://www.philosophypathways.com/vita.html

Latorshia asked:

Why doesn’t Descartes simply determine what’s real by looking around him and use his sense experience?

Answer by Helier Robinson

Your assumption is that everything empirical (i.e. known through the senses) is real; but this is not so, because some empirical data are illusory and thereby unreal. Illusions are contradictions within sense experience (e.g. the half immersed spoon in a glass of water, which is bent to the sight and straight to the touch) or between sense experience and well established belief (e.g. the railway lines appearing to meet in the distance) and there are no contradictions in reality. The business of finding out what in the empirical world is real is empirical science (as opposed to theoretical science, which tries to explain empirical reality by describing its underlying causes) and empirical science is still not yet complete.

Empirical reality may be defined as everything empirical that is not illusory, as opposed to theoretical reality which is every that exists independently of being perceived. It is widely believed that these two definitions are equivalent but in my opinion they are not, because of the argument from illusion. This is the argument that since illusions are unreal they are misrepresentations of reality rather than reality itself. In other words, illusions are false images of reality. But there is no clear distinction, in perception, between illusions and non-illusions, so non-illusions must be images of reality also. That is, illusions and non-illusions are all made of the same ‘stuff’, namely, sense data, which are sensations provided by the sense organs. The argument from illusion is widely disregarded because its conclusion is so opposed to common sense, but it has never been satisfactorily refuted.

Helier Robinson is Emeritus Professor in Philosophy, University of Guelph. His books are available from http://SharebooksPublishing.com.

Answer by Craig Skinner

Because he thinks REASON comes before OBSERVATION as the route to secure knowledge. He is a rationalist, as opposed to empiricist, philosopher. Of course all agree that reason and observation both contribute, the distinction between rationalists and empiricists is only rough and ready. and one of emphasis.

As a rationalist Descartes must reason his way to the view that he can trust his senses, not start off by taking sense experience as a reliable basis for knowledge. He notes that sense experience suggests, for example, a flat Earth, unmoving Earth, small sun and tiny stars – all incorrect.

Descartes is disenchanted with medieval philosophy based on Aristotle (who was pretty much an empiricist), and says he wishes to start from the beginning and build a solid foundation of knowledge for the sciences. His method is the famous Method of Doubt or methodological scepticism: he will only accept as knowledge what is so clear and distinct to his mind that it can’t be doubted, proceeding from there by reason.

He begins by doubting the evidence of his senses including the existence of the external world and his own body (at any time, he might be dreaming, or an evil demon could be deceiving him) Then he doubts even truths of reason (an evil demon could affect his mind tricking him into thinking 2+2=4 when it’s really nothing of the kind).

After all this doubting, is there anything left he can rely on? Yes, the fact that he is doubting means he is thinking, so he must exist (I think therefore I am, ‘cogito ergo sum’ in Latin).

Can he move on from there ? Is there anything else which is clear and distinct ? I suppose most of us would go straight from the Cogito to saying we had a clear and distinct idea of an external world including our own bodies, gained through sense experience. But, for Descartes, such a jump is unjustified. He says he has a clear and distinct idea of God as an omnipotent, omniscient, infinite, necessary being, and then argues as follows:

I. God therefore exists

2. God is no deceiver, so

3. I can (mostly) trust my God-given senses and reason.

4. My senses yield a clear and distinct idea of an external world including my own body.

5. These exist.

This argument from the Cogito back to the everyday world via God as a bridge is full of holes – do we all have this alleged clear and distinct idea of God (I don’t); even if we do, this doesn’t mean there is any God answering to this idea: even if there were a God, why shouldn’t he be a deceiver?

So he is no nearer to establishing the existence of the external world with CERTAINTY than he was when he started. But, as he says himself in the Synopsis of the Meditations, ‘no sane person has ever seriously doubted these things’. And of course it’s well known to the beginner in philosophy that the existence of the external world can’t be proved – solipsism, idealism, brains in vats, world-including-all-of-us as a simulation, all logically possible. But nobody really believes these things. One or two current philosophers argue that since there could be many simulations run by advanced intelligences but only one real world, it’s statistically more likely that we are virtual beings in an elaborate simulation rather than real flesh and blood humans in the real world, but I doubt they really believe it. If you are unsure, make sure you lead an entertaining (virtual) life so the higher intelligences stay interested and don’t switch off the simulation.

A final. important, philosophical point. Can we trust reason more than our senses ? The rationalist traditionally argues that reason yields a priori, analytic, necessary truths; observation yields second-class, a posteriori, synthetic, contingent truths. I wont go into the modern debate as to whether the analytic/synthetic distinction exists or whether the a priori is a coherent notion. But why should we trust our reason more than our senses?. Both can go wrong. Neither can be justified in any absolute sense – our senses can deceive us sometimes, and, logically speaking, could deceive us always. Likewise with our reason – we can only justify reason by reason, a circular argument. Ultimately we just accept our senses and our reason as generally reliable guides to the world. We can say, with Descartes, that they are God-given and so reliable, or, post-Darwin, that they are part of evolved human nature, promoting survival by being reliable guides to the world. My general view is that the senses and reason are on a par. As the Scottish philosopher, Thomas Reid, observed in 1764:

‘Why, sir, should I believe the faculty of reason more than that of perception? – they come both out of the same shop, and were made by the same artist: if he puts one piece of false ware into my hands, what should hinder him from putting another?’

So, in the end, Descartes does determine what’s real by looking around him, like everybody else, but with a deeper understanding than he had when he started, and we all do well if we manage the same.

Craig Skinner at PhiloSophos.com