There is no TV in your head – true or false?

Charles asked:

My philosophy teacher says there is no tv in your head. I believe there is because how do we picture past things like my 1st grade teacher vividly.

Answer by Craig Skinner

I’d like to argue, that I’m afraid your philosophy teacher is right.

The inside of your head is cramped and pitch dark. There is nobody in there to look at anything. And no screen to be looked at.

The confusion arises from the sense-datum representational theory of perception. According to this, when I look at, say, a tree, a representation of the tree is formed in my mind. So far, so good, and true in my view. But the next step goes wrong. This representation is regarded as a picture (sense datum), and THAT is what I am looking at. Naturally, to see this picture in my head (on a tv screen if you like), a viewer is needed. So the little viewer in my head looks at the picture and sees the tree. But how does THIS viewer see it. By forming a little picture in his little head, and an even tinier viewer therein looks at that picture. And so on. An infinite regress of ever-tinier little men (homunculi) inside ever-tinier heads looking at ever-tinier pictures. Clearly absurd.

When you look at a tree, it is YOU who sees it, and what you see is the TREE, not some picture in your head. The way you do this is by converting the features of the tree, encoded in the pattern of light reaching your eyes, into patterns of electrical impulses going from eye to brain which result in a pattern of nerve cell activation in the brain corresponding to YOU seeing the tree. There are no non-physical entities in your head which must themselves be viewed. You simply see ‘treely’ as it were. Similarly, when you look at a post box, you don’t look at a red image in your head. You just see ‘redly’.

You can indeed picture your 1st grade teacher vividly. When you experienced her presence live, a particular pattern of brain activity corresponding to your seeing (and hearing) her was set up. This pattern faded as soon as a new one took its place in your consciousness. But not before the pattern was transferred to the hippocampus (the brain area for long-term memory) and laid down long-term partly as continuing activity patterns, partly as molecular changes. You can access these memories, and when you do, the pattern of brain activity you had when seeing the teacher is replicated so that you seem to see her now. Not an exact replication, because, although the recall is vivid, you know she is not really standing before you.

What I am advocating is indirect (representational) realism as an account of perception, but an ‘adverbial’ rather than a ‘sense datum’ view. You should read about these, as well as the direct realism and phenomenological accounts of perception (both incorrect in my view).


Nietzsche on truth, lies and interpretation

Laura asked:

If Nietzsche’s theory was there is no truth as we understand truth to be defined, does that mean that all there is are lies?

Answer by Shaun Williamson

No, it doesn’t. In philosophy words have no context so we invent a (wrong) context for them. You see the word truth and you think of truth vs lies. You could also have thought of truth vs beliefs.

Nietzsche was thinking of truth vs interpretation. I think he said something like 1. There is no such thing as truth, there is only interpretation Now of course if he is right then 1. isn’t true either it is only his interpretation. So we are being asked to found our theory of truth on something which is not true.

I think he was thinking mainly about things like history and literary criticism. He wasn’t thinking about mathematical or logical truth or even scientific truth.

The value in what he said is that he reminds us that often our most important beliefs are just based on the world as we see it and interpret it. We interpret history, literature, art from our 21st century perspective in a particular society and we can never be completely free from our inbuilt preconceptions.


Paradox of the tattoo artist

Stella asked:

Here is a puzzle that requires some ‘conceptual analysis’. You really need to think about the meaning of the words involved and the way this guy Eugene is described!! Good luck!!

RICK: Let me tell you about my hometown, Tattoopolis, and my favorite tattoo artist there, Eugene. As of today, everyone in my hometown has exactly one tattoo (though they could have more in the future). That of course makes it an interesting town. But Eugene is even more interesting! Eugene tattoos all and only those people in the town who do not give tattoos to themselves! That’s right: he tattoos all people in the town who don’t give tattoos to themselves, AND he only tattoos people in the town who don’t give tattoos to themselves.

SLICK: Wow, that’s quite a story there, Rick. Too bad it’s false. I know for sure that there’s no such person as Eugene.

Slick is right. There is no such person as Eugene. Slick knows this even though he has never been to Tattoopolis nor has he ever talked to anyone from Tattoopolis (other than Rick). As a matter of fact, Slick doesn’t need to know anything else about Tattoopolis or who lives there to know that there is no such person as Eugene.

So how does he know that Eugene does not exist? (Hint: It has to do with the concept that supposedly applies to Eugene).

Answer by Geoffrey Klempner

The short answer to your question is that the description of Eugene is self-contradictory. Self-contradictory entities (like round squares) cannot exist.

That’s it.

However, there is a longer and more interesting answer. The story of Slick and Eugene is in fact a version of a well known paradox known as the ‘Barber paradox’. There is a Barber in [whichever city you like] who shaves all and only those men who do not shave themselves. Does he shave himself or not? (I suspect that the barber has been changed to a tattoo artist to encourage gender equality!)

The Barber (or Tattoo) paradox isn’t really a paradox. There’s no problem to solve, once we see that it has a solution, albeit one that involves rejecting a question. We reject the question whether the barber shaves himself or whether the tattooist tattoos him/ herself, for the same reason as I would reject the question whether or not I have stopped beating my wife. I haven’t stopped beating her and I haven’t not stopped beating her, because I have never beaten her. The barber does not shave himself and does not not shave himself because, logically, there can be no such barber.

If this is all paradoxes amounted to, then they wouldn’t cause such headaches for philosophers. However, there are other paradoxes which have caused great consternation and for which there is no agreed solution.

One paradox which is very similar in form to the Barber paradox is Russell’s Paradox, originally discovered by Gottlob Frege. Consider classes which are not members of themselves. The class of carrots, for example, isn’t a carrot. On the other hand the class of abstract objects IS an abstract object.

Let’s take the class of ALL the classes, like the class of carrots, which are not members of themselves. Is it a member of itself or not? You already know the answer, if you’ve followed the explanation of the Barber paradox. There is, logically can be, no such class.

But that is genuinely paradoxical. There seems no logical reason why we can’t form a class of all the classes which are not members of themselves! Russell spent years on this — according to his Autobiography it drove him to the brink of despair and ruined his marriage — finally coming up with a solution that he was not fully happy with, because it involves a rule restricting the formation of classes whose only real motivation is that it avoids the paradox. Other mathematicians and philosophers have proposed their own solutions, which are no less arbitrary.


Descartes’ attempt to prove the existence of an external world

BM asked:

How did Descartes prove res extensa basing from his argument cogito ergo sum?

Answer by Craig Skinner

Short answer: he didn’t succeed.

Descartes felt that a new grounding of knowledge was needed for science, the traditional Aristotelian grounding being unsound.

This sure knowledge to be reached by reason alone (not observation) from what remains certain after using the Method of Doubt.

The Method of Doubt is to accept as true only what is presented so clearly and distinctly to the mind as to be certain.

First, then, he must doubt everything learned through the senses (all empirical or a posteriori knowledge as we would say). For the senses can deceive, and also, at any moment, he can’t be certain he is not dreaming, or that his mind is not controlled by an ‘evil genius’ which deceives him about everything.

Secondly, he must doubt all truths of reason (rational or a priori knowledge). He feels that, even if dreaming, he knows that 2+3 = 5, but he considers that an evil genius could deceive him about mathematical truths, interfering with his thought every time he adds 2 and 3 so that he is sure (wrongly) that the sum is 5.

Having done all this doubting, the only certainty remaining, the Archimedean fixed point as he calls it, is ‘ I think therefore I am’ (the cogito).

Unfortunately his arguments back from the cogito to knowledge of a physical world of concrete things, including other people and his own body, are flawed (see details below).

The upshot is that one of his legacies is scepticism, rather than its resolution, and strong philosophical scepticism (about matter, the external world, causation and selves) later emerges, for example in the views of Berkeley and Hume.

His argument from the cogito can fairly be stated as follows:

1. I can’t doubt my existence as a thinking thing, so I know this (the cogito).

2. I know it solely by clear and distinct perception.

3. So, what I perceive very clearly and distinctly is true.

4. I have a clear and distinct idea of God.

5. The idea of God includes necessary existence, so God exists.

6. God, being all good, is no deceiver.

7. So, I can rely on my God-given reason and senses, properly used.

8. Using them I have clear and distinct ideas of extension, size, shape, situation, movement, duration and particulars of an external world.

9. So, the external world, including my body, exists.

Clearly we can challenge the argument at many points. I wont deal with all these challenges, but here are examples:

3. People have perceived all kinds of things clearly and distinctly but which are not true eg:

* sinners suffer eternally in hell.

* the Earth is flat.

* some people (say, women or some ethnic groups) are intellectually and morally inferior.

* flies/rats spontaneously generate in compost heaps/mud respectively.

5. Fine, IF God exists his existence is necessary, but this tells us nothing about WHETHER God does exist.

6. God (or the gods) could be jokers who get a kick out of deceiving us.

Of course Descartes didn’t really doubt that there is a world out there, or that he had a body. His scepticism is a ploy (methodological scepticism) to try to put his views on a rational footing.


What use is formal logic to philosophy?

Stephen asked:

Greetings Philosopher-Kings! My question to you is of a practical nature but I feel would fall outside of the Problem Removal Service. I am only beginning my self studies in the field of philosophy and have been groping around to find the most efficient path to becoming relatively well-versed in philosophy. What I respect the most about the study of philosophy is the ability of the philosophers I have met or read to quickly and clearly identify the flaws in the premise or structure of an argument. I have assumed this was due to their background in formal logic.

My question then is ‘How integral is Logic or Advanced Logic to the study of philosophy as a whole, and is it simply useful in some fields such as philosophy of language or mathematics, and not in others, such as ethics or political philosophy where perhaps only a basic understanding of argumentation theory would be necessary. Moving forward in the study of philosophy (and any of the other common fields in academia for that matter) would the study of Logic be very beneficial?

(If you are feeling generous, some names of a few good books to get started in the field would be a great help.)

Answer by Craig Skinner

I’m no philosopher-king, actual or potential, but having reached the end of the beginning (recent distance-learning BA Philosophy with Pathways support), maybe I can help you as an acknowledged beginner.

You say you are ‘groping around to find the most efficient path’. In my view, there is no substitute for hard work, and it needs to be focussed, interactive and challenged. Best is to sign up for some qualification (diploma, degree, Pathways modules all suitable). Self-study alone, although educational and fun, tends to be diffuse and unrigorous. You need to be writing essays which are critically appraised by somebody further along the road, and aiming to pass exams or submit a dissertation within a definite time frame.

What about formal logic?

There is no need for fluency in the formal languages of logic in order to study and understand philosophy. The 2010 study guide for the London BA (Phil) says in its blurb about the compulsory Philosophical Logic module ‘Formal logic does not figure as such in the examination…., but some knowledge of elementary formal logic is necessary for the subject as a whole’. It then goes on to recommend a book offering a ‘gentle introduction’ to formal logic (more from me below).

I got excellent marks in my Philosophy of Mathematics, Philosophy of Science and Philosophical Logic modules with no more knowledge of formal logic than a ‘gentle introduction’.

As a student of philosophy your focus will be analysis of and reflection on concepts arising out of/built into logic and reasoning – deduction, induction, abduction, validity, identity, necessity, truth, reference, definite descriptions, conditionals. In addition you may wish to reflect on the reasons for the existence and the value of non-standard logics which deny bivalence or deny Aristotle’s laws such as LEM or even LNC. Also a basic understanding of nonbivalent, including fuzzy, logic, is needed to understand the concept of vagueness.

In addition you will be familiar with notions that long predate formal logic, such as circular argument, begging the question, equivocation, reductio ad absurdum.

I think too much 20th Century analytic philosophy writing was infected by logical symbolism, but the heyday of this has passed and philosophical logic is re-emerging with new vigour after decades of debility due to that infection. The love affair between analytic philosophy and logical symbolism blossomed with publication in 1905 of the Theory of Descriptions in Russell’s ‘On Denoting’ (that ‘paradigm of philosophy’ as Ramsey called it in 1931). Russell was seen as ushering in a new age of rigour – many old philosophical problems would simply be shown up as confusions of thought; woolly Continental metaphysics was exposed; Meinong’s alleged nonsense about nonexistent objects was supposedly rebutted. And indeed it was a shot in the arm to philosophy, although our view of it is more nuanced these days, and logical analysis of language delivered less than was hoped for. But, at any rate, Russell couched his theory in the symbolism of his (and Whitehead’s) Principia Mathematica, starting the trend of discussing such matters in terms of symbolism when they can be understood without it (of course it is true that some people find it easier to grasp ideas symbolically).

As for the gentle introductory text, I have the main contenders on my bookshelves, including Hodges, Newton-Smith and Guttenplan, and have read them. They are all more than adequate. I think the best is Guttenplan:

Guttenplan S (1997) The Languages of Logic; an introduction to formal logic, 2nd ed., Blackwell

All the best with your studies.


Why were my comments deleted?

Robert asked:

I see that your moderators pull many comments. The few comments that make it through the ‘gauntlet of censorship’ disappear at month’s end via a full comment board wash. My philosophical question is what is the REAL, GENUINE, TRUTHFUL purpose of these actions? I personally often find that comments are more insightful than the questions, stories or philosopher responses. What place does moderation or censorship have in philosophy? Please send a genuine and truthful answer as I would expect nothing less from genuine philosophers.

Answer by Shaun Williamson

Robert this is a site where people can ask questions about philosophy. They can also comment on questions that other people have asked. What they cannot do is use the site to expound or publish their own philosophical ideas. That is what you have been trying to do Your comments are not relevant to the questions you are commenting on.

You are not being censored, your comments are being removed because they are not RELEVANT to the questions you are commenting on. Don’t try to use the site to publish your own philosophical ideas. Go and write a book or an essay. If you wish to ask a question then ask a question.

Do not use this site to try to publish your own ideas, that is not what this site is for.


Answer by Peter Jones

Hello Robert. This post of yours and others that have not appeared are the reason that this site needs to be moderated. That is, it is posts such as yours that create the need for moderation. They are muddled, opinionated, immoderate, dogmatic and completely out of place in a philosophical discussion. If you cannot see this then perhaps you could try taking an online or college philosophy course and seeing how you get on.


Answer by Stuart Burns

Having read a number of your posts to this forum, I regret to inform you that I agree with the Moderator in ‘censoring’ your contributions (or at least those contributions I have read so far).

Your posts simply expound a particular view without offering any argument, or philosophical basis, for your position. Nor do they appear to address the questions for which your posts are supposed to be an answer. Your comments are offered in the manner of ‘received wisdom’ – offering no possibility that they might be in error in some fashion. They do not offer anything that any other philosopher who might disagree with you, can come to grips with. In other words, I can find no place to suggest where you might have made an error in fact or logic. I can only disagree with you – hardly a propitious beginning for a philosophical discussion, and more akin to theological debates.

Consider your post above. You seem not to understand the purpose and function of the ‘Ask a Philosopher’ web site. It is not a general forum for free posting of ‘comments’. It is designed (and, yes, moderated) to be a forum for philosophical responses to philosophical questions. The answers posted are intended to be reasoned responses, frequently drawing on the large history of writings of well known philosophers.

The questions that I choose to answer, as just one of the contributors, are those questions that tweak my interest as offering some interesting aspect on a philosophical issue. I am sure that other contributors have other criteria for questions that initiate their own responses. So if you would like your contributions to ‘make it through’ the moderation and censorship, you might like to try composing a more pointed philosophical response to some question, instead of simply commenting on the general area of the question.

While you personally may often find that comments are more insightful than questions or philosophical responses, please keep in mind that this web site is not intended for ‘comments’. It is the philosophical nature of the question and response that are the intended format of the service. Perhaps you may find a more suitable venue for your comments on one of the many philosophical forums on the web. I can start you off by suggesting


Answer by Geoffrey Klempner

As the sole moderator for Ask a Philosopher I take full responsibility for all decisions to include or exclude comments posted on answers provided by the Ask a Philosopher panel members. I am also responsible for choosing which of the answers submitted by panel members to publish on the Ask a Philosopher pages.

I do not enter into personal correspondence over particular issues of moderation with visitors to the site. However, I felt that it would be valuable in this instance to air the matter here.

In this case, I felt that my moderation needed to be moderated, so I showed the deleted comments to members of the panel and asked for their views. Those who expressed an opinion, said that they fully agreed with my decision. If they had disagreed, then we would have debated it.

The bar is in face set rather low. We do not exclude comments because they are insufficiently intelligent, or because we think they are misguided, or based on a misunderstanding of the question or the answer, or just plain wrong. One learns from other people’s errors. Apart from spammers, very few comments are deleted. But Robert’s comments on this occasion were below the bar.

Robert is welcome to continue submitting questions and comments. However, if he doesn’t like the way Ask a Philosopher is moderated then I would advise that he looks elsewhere for forums where he can freely express his opinions without fear of being ‘censored’.


What do we want from answers?

Steve asked:

What do we want from answers?

Answer by Eric George

What is given to us by answers and to which what we as human beings desire from answers, is of course; truth. Herein however, lays before us an even deeper question – ‘But what is truth?’ Truth, it could be said, is what is ultimately correct and objective (and therefore by nature not subjective).

By objectivity (that which is ‘objective’) we mean a fact concerning something which is completely autonomous of personal opinion, in other words – something concerning given reality which is or would be true whether one person in the world or no one in the world believes it to be true or not. And of course this follows that by subjectivity (that which is ‘subjective’) we mean to be an opinion based belief, this belief being true or not has nothing necessarily to do with someone believing that particular belief.

For example, suppose there exists a room of ten people where nine of the ten people do not believe the existence of gravity to be true (despite them all not floating around in mid-air), the tenth person however does indeed believe in the existence of gravity to be real. Now, just because the majority of persons in the room hold a belief which denies the existence of gravity does not mean at all that they are correct – on the contrary, in this scenario, it is the minority of one person who holds the belief that gravity is objectively true, that is correct.

So answers naturally follow questions (or at least try to ‘catch’ questions upon following), and questions are formulated by human beings who wish to interpret or unveil reality for what it really is, to explain what essentially is. In that, logic and rationality were not invented subjectively, they were discovered objectively as the blueprints of explanation, discourse and understanding.

We ask questions about reality and all that it encompasses in order to ascertain truth by answers to these questions. Now, permit me to clarify something here, of course just like most things in life not everything is so ‘black & white’, especially when dealing with the very nature ‘answers’. That is, not all answers are true since an answer to a question or inquiry could very well be false, so opinionated answers although they could be true (an opinion based upon objective truth is merely an extension of the fact itself, rather than a deviation from it) are probably more often than not, simply untrue.

Because for all opinionated answers to be true, this would mean that every or any single opinion held by any person in the world could all be true at the same time, which would going back to our scenario, make all ten people correct despite the nine being objectively wrong. Truth therefore, by definition is exclusive – and answers which seek to fulfil corresponding questions must be objectively true, wholly apart from opinion and totally binding across all planes irrespective of cultural or social conditions.