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Thomas Nagel: What Does It All Mean? A Very Short Introduction to Philosophy

By Levi Clancy for Student Reader on

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Philosophy is different from science and from mathematics. Unlike science it doesn't rely on experiments or observation, but only on thought. And unlike mathematics it has not formal methods or proof. It id done just by asking questions, arguing, trying out ideas and thinking of possible arguments against them, and wondering how our concepts really work. (Nagel, p 10)

We couldn't get along in life without taking the ideas of time, number, knowledge, language, right and wrong for granted most of the time; but in philosophy we investigate those things themselves. (Nagel, p 11)

Nagel asserts that the best way to learn about philosophy is to ask questions. Specifically, these:

How do we know anything?

  • Is it a meaningful possibility that the inside of your mind is the only thing that exists -- or that even if there is a world outside your mind, it is totally unlike what you believe it to be?

  • If these things are possible, do you have any way of proving to yourself that they are not actually true?

  • If you can't prove that anything exists outside your own mind, is it all right to go on believing in the external world anyway?

If you think about it, the inside of your mind is the only thing you can be sure of. (Nagel, p 13)

Ordinarily you have no doubts about the existence of the floor under your feet, or the tree outside your window, or your own teeth. In fact most of the time you don't even think about the mental states that make you aware of those things: you seem to be aware of them directly. But how do they really exist? (Nagel, p 13-14)

Nagel proceeds with the old "how do you know you're not dreaming?" trick, then goes on to try out the haggard old "how do you really know you even have a body or a brain?" yarn. The most radical conclusion: "Your mind is the only thing that exists." This view is called solipsism. On solipsism,

It is a very lonely view, and not too many people have held it. As you can tell from that remark, I don't hold it myself. If I were a solipsist I probably wouldn't be writing this book, since I wouldn't believe there was anybody else to read it. ... Perhaps you are a solipsist: in that case you will regard this book as a product of your own mind, coming into existence in your experience as you read it. ... On the other hand, to conclude that you are the only thing that exists is more than the evidence warrants. You can't know on the basis of what's in your mind that there's no world outside it. (Nagel, p 15)

Solipsism is more radical than the softer-toned skepticism,

Perhaps the right conclusion is the more modest one that you don't know anything beyond your impressions and experiences. There may or may not be an external world, and if there is it may or may not be completely different from how it seems to you -- there's no way for you to tell. This view is called skepticism about the external world. (Nagel, p 15)

An even stronger form of skepticism is possible. ... If you can't be sure that the world outside your mind exists now, how can you be sure that you yourself existed before now? How do you know you didn't just come into existence a few minutes ago, complete with all your present memories? The only evidence that you couldn't have come into existence a few minutes ago depends on beliefs about how people and their memories are produced, which rely in turn on beliefs about what has happened in the past. ... You would be assuming the reality of the past to prove the reality of the past. (Nagel, p 17)

Nagel on Knowledge

I. You can be certain of the contents of your own mind.
2. You can only have contact with any external objects by means of those mental contents.
3. But those mental contents might not correspond to any real object.
4. Thus we can only be certain of the contents of our own minds.

Nagel on the Mind

The Problem:
Assume that we *can* know about things through observation (as opposed to the above argument). Even if we can have knowledge by observation, it does not seem we can observe minds or mental contents directly (thoughts, feelings, sensations, etc). So what is a mind? Is it just the brain? Nagel thinks not. Thinks the mind is a thing independent of the body.

Yes. Because
1. The universe is just matter/things that are observable with the senses.
2. Science will eventually explain away the mind.
Nagel: But it doesn't seem it *can*. It cannot be said of any piece or collection of pieces of matter that it *thinks* or *feels*, only that conscious beings do. Thus the material explanation of the mind just cannot work.

The mind and mental events are just descriptions of how bodies behave under certain circumstances. Pain is just recoiling due to injury. Nothing is going on "inside", because there is no "inside".
Nagel: But pain *feels* like something, there is the experience of pain. That is not just behavior.


The first line of Nagel's first chapter states that, when you think about it, the contents of your own mind are the only things you can be certain of. Do you think that is true? Why or why not?
If I remember correctly, Nagel asserts that you may only be certain of your mental self. Indeed, he suggests that even the contents of your own mind may be an illusion: memories placed there to convince you of your own past, when you in fact only came into existence moments ago. There are mental illnesses where people fail to recognize themselves as "self" and this feeling of foreignness and dissociation can, in extreme cases, manifest itself as the conviction that oneself is dead. Also, anybody with close friends/family suffering from schizophrenia will know firsthand the terror, dread and awe that comes from being around somebody completely dissociated from reality. Are the contents of your mind truly reliable? Is eyewitness testimony truly reliable? The answer is no. However, the scientific method, duplication, corroboration and other techniques give me confidence when I draw certain conclusions about the world around me (for example, when I do my hobby research into genealogy).

Other minds

The Mind-Body Problem

The view that the brain is the seat of consciousness, but that its conscious states are not just physical states, is called dual aspect theory. It is called that because it means that when you bite into a chocolate bar, this produces in your brain a state or process with two aspects: a physical aspect involving various chemical and electrical changes, and a mental aspect -- the flavor experience of chocolate. When this process occurs, a scientist looking into your brain will be able to observe the physical aspect, but you yourself will undergo, from the inside, the mental aspect: you will have the sensation of tasting chocolate. If this were true, your brain itself would have an inside that could not be reached by an outside observer even if he cut it open. ... We could express this view by saying that you are not just a body plus a soul -- that you are just a body, but your body, or at least your brain, is not just a physical system. It is an object with both physical and mental aspects: it can be dissected, but is also has the kind of inside that can't be exposed by dissection. (Nagel, p 33)

The meaning of words

Free will

Determinism, free action,

Right and Wrong

Moral argument tries to appeal to a capacity for impartial motivation which is supposed to be present in all of us. Unfortunately it may be deeply buried, and in some cases it may not be present at all. In any case it has to compete with powerful selfish motives, and other personal motives that may not be so selfish, in its bid for control of our behavior. The difficulty of justifying morality is not that there is only one human motive, but that there are so many. (Nagel, p 65)

The ideas of wrong and right are different from the ideas of what is and is not against the rules. Otherwise they couldn't be used in the evaluation of rules as well as of action. (Nagel, p 52)

For the above, Nagel gives the example of a law (racial segregation) mandating something which is wrong.

This reminds me of the famous old quote.

There are just laws and there are unjust laws. I would agree with St. Augustine that an unjust law is no law at all... One who breaks an unjust law must do it openly, lovingly...I submit that an individual who breaks a law that conscience tells him is unjust, and willingly accepts the penalty by staying in jail to arouse the conscience of the community over its injustice, is in reality expressing the very highest respect for law." (Martin Luther King, Jr via

You generally view as wrong that which you would not want done to yourself, even if a slipper slope is involved. If someone is willing to steal a library book, could they also steal some of your silver? It is best to reprimand them and not partake. You do not want your silver stolen. To think of a world where theft is rampant instills a feeling of dread. It preoccupies the mind. Thus, maybe rather than loving or fearing a deity, your are loving or fearing yourself. Would a hit-and-run be fine if nobody knew I did it, if even the corpse were never found? No. I'd publicly announce that I'd done it. I'd want the perpetrator to do that if I had been the victim. I'll make an example out of myself. If there is no fear of being caught, then I'll create a reward: knowing that I did the right thing irrespective of an audience, and that I created an audience to ensure my deed was known.

Some people believe that even i you can get away with awful crimes on earth ... such acts are forbidden by God, who will punish you after death (and reward you if you dind't do wrong when you were tempted to). So even when it seems to be in your interest to do such a thing, it really isn't. ... A more appealing version might be that the motive for obeying God's commands is not fear but love. He loves you, and you should love Him, and should wish to obey His commands in order not to offend him. ... Some people have even believed that if there is no God to back up moral requirements with the threat of punishment and the promise of reward, morality is an illusion: "If God does not exist, everything is permitted." (Nagel, p 54)

However, three objections arise. First, many non-religious people still have morals. Second, God may forbid something because it is wrong, not the other way around. Third, fears and rewards might not be the right motives for morality. This last objection applies to other explanations about morality, too.


Equal opportunity produces unequal results. ... What kinds of causes of inequality are wrong? (Nagel, p 66, 67)


Everybody dies, but not everybody agrees about what death is. Some believe they will survive after the death of their bodies, going to Heaven or Hell or somewhere else, becoming a ghost, or returning to Earth in a different body, perhaps not even as a human being. Others believe they will cease to exist -- that the self is snuffed out when the body dies. And among those who believe they will cease to exist, some think this is a terrible fact, and others don't. (Nagel, p 73)


Read chapter 9 from Nagel's book carefully (you should also know the rest, especially chapter 4 on the mind-body problem). It's a very short chapter. I can find three main parts of that chapter. How many do you find, what are they, and what are they about?
Explain Nagel's notion of a negative good or evil. Try do provide a definition of this technical term on the basis of what Nagel says about it.
In the paragraph following the paragraph where Nagel introduces the notion of a negative good/evil, Nagel sketches a view to the effect that death cannot have either a positive or a negative value for anybody. This claim is justified on the basis that 'Someone who does not exist can neither experience something good, nor bad'. Try to extract from that paragraph an argument with between two and four premises (I have two, but that can vary), and a conclusion. The conclusion should be something like, 'Therefore, death is neither good nor bad for the person who is dead.' In doing so, use what Prof.Copenhaver told you about arguments in lecture. The argument should be structured as P1, P2, C. Make the argument valid. Then discuss whether it is sound. That is, discuss whether you think each premiss is true, and why. If you think one premise is false, try to provide a counterexample to that premise.

The meaning of life

The idea of God seems to be the idea of something that can explain everything else, without having to be explained itself. ... The idea that our lives fulfill God's purpose is supposed to give them their point, in a way that doesn’t require or admit of any further point. One isn’t supposed to ask "What is the point of God?" any more than one is supposed to ask, "What is the explanation of God?" ... Can there really be something which gives point to everything else by encompassing it, but which couldn't have, or need, any point itself? ... If God is supposed to give our lives a meaning that we can’t understand, it’s not much of a consolation. God as ultimate explanation, may be an incomprehensible answer to a question that we can't get rid of. On the other hand, maybe that's the whole point, and I am just failing to understand the religious ideas. Perhaps the belief in God is the belief that the universe is intelligible, but not to us.Nagel § 10 ¶ 11-14

Unexplained ExplainerNagel asserts that god explains unexplainably. According to Nagel, belief in god offers an eventual philosophical conclusion: a religious practitioner does not ask fundamental why questions about god, such as what about before God?
TautologyTo bolster his doubts about god, Nagel offers a typical Aristotelian infinite transgression whereby god inquiries devolve into tautology. There comes an end-point where questions about god must be answered tautologically, such as a question about before god is irrelevant, because god has always been. A further but why would be tantamount to questioning the religion itself.
MeaningfulnessNagel posits that because he cannot rigorously and completely understand and interrogate god -- that he is not consoled. By lacking consolation, Nagel seems to mean he does not rest assured that god provides a true philosophical end-point. He is uneasy about it because he rejects the notion that an incomprehensible answer can be the full explanation.
BelievingNagel concludes that perhaps the belief in god (accepting an unexplained explainer) is the belief that the universe is intelligible (that there is a natural order) but not to us (but it is beyond our comprehension). In other words: belief in god may be distilled to a belief that there is order and sense in the universe, but that it is beyond our understanding.

Nagel has grouped his book into ten sections: an introduction, followed by nine realms of philosophy. In the second section, he probes whether we know the universe exists outside out own mind; in the third, he dissects existence of minds besides our own; in the fourth, he tries to extract mind and body from one another, if such a feat may be done at all.

Nagel has mostly takes a bare-bones approach that posits less than it strips away -- he favors challenging common assumptions rather than putting forward (large, overwrought) solutions to encompass all his questions. But he does concede some middle ground to hedge against the most radical philosophical conclusions.

If a belief in the world outside our minds comes so naturally to us, perhaps we don't need grounds for it. We can just let it be and hope that we're right. And that in fact is what most people do after giving up the attempt to prove it: even if they can't give reasons again skepticism, they can't live with it either. But this means that we hold on to most of our ordinary beliefs about the world in face of the fact that (a) they might be completely false, and (b) we have no basis for ruling out that possibility.Nagel § 2 ¶ 24

Nagel cautiously puts forward that modest skepticism is admissible: that indeed, there is little way to know for sure that there is anything beyond our immediate senses. Despite the vulnerability of his position, he posits it nonetheless as a philosophical starting point.

Nagel's approach is consistent, whether dealing with knowing or dealing with god. He is unwilling to make any concrete statement about what reality is and he is similarly unwilling when it comes to god. Religion strikes me as synonymous with faith except in procedural or cultural senses, and Nagel's resistance to fully place faith in reality is consistent with his lack of total faith in god.

The only experiences you can actually have are your own: if you believe anything about the mental lives of others, it is on the basis of observing their physical construction and behavior. ... What can you really know about the conscious life in this world beyond the fact that you yourself have a conscious mind? Is it possible that there might be much less conscious life than you assume (none except yours), or much more (even in things you assume to be unconscious)?Nagel § 3 ¶ 3, 20

Nagel begins and ends this section on the same point -- he really doesn't get very far, besides providing examples to reinforce the notion that the way two people experience the same thing may be vastly different. Two peoples' experiences of cold may be totally different. Further, personal bias is supreme in subsequent parsing of this experiential data, particularly beyond the simplest physical stimulation.

While it is impossible to truly compare experiences between different people, at least experiences have the same relative relationships within a single person: sweetness may be different between two people, but sweet versus bitter is the same within everyone. This gets foggy when considering sensory disorders, hallucinations and simple differences: aspartame may be sweet to one person, but soapy to another.

Nagel does not sweep away any of this ambiguity about other minds -- in fact, he encourages it and expands to posit that there may be entirely other forms of consciousness. His perception is not purely empirical. As such, it does not preclude his later considerations about god.

For anything to happen in your mind or consciousness, something has to happen in your brain. ... But there is also a philosophical question about the relation between mind and brain, and it is this: Is your mind something different from your brain, though connected to it, or is it your brain?Nagel § 4 ¶ 3, 5

Nagel outlays this section: his considerations of whether the mind entirely physical, entirely ethereal, some mix of the two or something else. He makes a few valid points: things induce chemical changes in our brains, but those things are not present in our brains; and there is no way to get inside of somebody's mind to experience their experiences.

Nagel describes dualism (entirely separate, a mind interacts with the body), physicalism (the mind is the body) and dual aspect theory (yes, the mind is physical -- but the brain also has non-physical aspects). He tosses around defense and critique of these systems. Extracting the particulars of Nagel's beliefs is a bit messy, but he concludes that there is an intangible aspect, but its so inextricable from the physical being that little is known about either one alone.

When a lot of physical elements are put together in the right way, they form not just a functioning biological organism but a conscious being. If consciousness itself could be identified with some kind of physical state, the way would be open for a unified physical theory of mind and body, and therefore perhaps for a unified physical theory of the universe.Nagel § 4 ¶ 26

Nagel so far has mentioned that we may not be entirely sure of existing outside of our own mind -- but more importantly, he has mentioned that there may be forms of consciousness entirely unknown to us, and also that there may be a unified physical theory of the universe. Nagel is hesitant to leap into faith in god, which he views as a termination of philosophical interrogation. However, when directly discussing god, he wonders if perhaps it is belief that the universe is intelligible -- just not to us.

Perhaps the belief in God is the belief that the universe is intelligible, but not to us.Nagel § 10 ¶ 14

Nagel's philosophical inquiries are examples of metaphysics, a field formalized by Aristotle in μετάφυσικά Metaphysics. Book XII of μετάφυσικά Metaphysics seeks to establish truths about many things including god, which Aristotle believes in. However, Aristotle also casts away mythology in favor of provable truths. Aristotle seeks out a primary mover against which the rest of the universe is subordinate. Though Nagel's use of the word God could be misinterpreted to suggest he is atheist unlike Aristotle, in fact he and Aristotle are very similar in that both of them disregard fanciful doctrine (God, mythology) and support the idea of an intelligible unifying theory -- a primary mover, a god in a philosophical sense.

Our forefathers in the most remote ages have handed down to their posterity a tradition, in the form of a myth ... they say these gods are in the form of men or like some of the other animals ... But if one were to separate the first point from these additions and take it alone-that they thought the first substances to be gods, one must regard this as an inspired utteranceAristotle, Metaphysics §8 ¶6

Aristotle finds the universe intelligible: this is innate, as he actively pursues understanding the universe without any blocked-off zones of unchallenged mysticism. Indeed, he casts away mysticism and distills what he accepts as philosophical assumptions: that the first substances were gods, something intuitively known by early mankind. Aristotle definitely thinks that god exists. In fact, Aristotle believes that because he thinks of god, desires to know god, that therefore god exists.

For if there is to be a movement for the sake of a movement, this latter also will have to be for the sake of something else; so that since there cannot be an infinite regress, the end of every movement will be one of the divine bodies which move through the heaven.Aristotle, Metaphysics XII §8 ¶5

It is able to move him, and the entire universe, without being moved itself -- a primary mover is the source of all movement in the entire universe. Further, because god is not desired for external reasons, but for pure pursuit of knowledge, Aristotle deems that the primary mover is good.

Its mode of being is good, and it is in this sense a first principle. ... God is a living being, eternal, most good, so that life and duration continuous and eternal belong to God; for this is God. Aristotle, Metaphysics XII §7 ¶2,3

Nagel is not consoled by the idea of an incomprehensible god figure, and Aristotle dismisses such a notion likewise. They instead both turn to something more abstract: Nagel to a unifying theory of the universe; Aristotle to a primary mover. There is a relationship between dismissing an unexplained explainer and pursuing a one. By casting off the philosophical limits of the former, forbidden from challenge by dogmatic tautology, then the thinker is free to think about the one.

If God is supposed to give our lives a meaning that we can’t understand, it’s not much of a consolation.Nagel, §10 ¶14

Nagel leaves many questions unanswered, but he is clearly unsatisfied by the religious notion of a deity -- he yearns for knowledge. He is not consoled by accepting a unified worldview in exchange for being unable to rigorously interrogate such a worldview. Aristotle seeks to understand the primary mover, and in doing so he reveals that he suffered the same discomfort as Nagel: a sense that acceptance was not enough, but mental pursuit was most good. Indeed, it is Aristotle's pursuit that reinforces Nagel's statement about consolation. It was only through full inquiry that Aristotle and Nagel can attain consolation.