Please keep checking back as I will be updating this page with definitions and comments. For the time being, this is the handout I distributed in class. You are supposed to known the meanings of the terms below and you are also supposed to have the answers to the questions. By the time we have finished this section - before we move to the problems of 'other minds' and 'induction,' I will have also provided a lot of information myself. But, until then, the exercise for you is to take notes in class and see if you can fill out the information below by yourself.


Bertrand Russell, “Appearance and Reality,” and “Idealism.’

Rene Descartes, Meditations on First Philosophy in Perry & Bratman, editors, Introduction to Philosophy: read the first two Meditations.}

I. Metaphysics The branch of philosophy that investigates the ultimate nature of reality.

Our original reaction as human beings - as non-philosopical human beings, that is - would be to say that we just know what is real and what is not. As you will find out in the next lecture, 'knowing' is also something we cannot take for granted. If 'to know' means what it is supposed to mean, then, we will need rigorous criteria for THAT too - for what constitutes knowledge. Let's get back to what is real. Should we assume that the ral is what is accessible to our senses? But, wait a minute: What about the thoughts in your head? Aren't they 'real'? Are those thoughts accessible to your senses - can you see, hear, or touch your thoughts? If a brain surgeon performed probing brain surgery, without total anaesthesia, he or she could see something about the chemistry of your brain, of course; but, would THAT be your thoughts? Actually, the doctor does not even see, touch, or smell the chemistry either - at least, not the chemical equations that describe the chemical events that are taking place in your brain at any given moment.

Or, consider this example: Isn't the US Constitution real? Well,it must be. But is the US Constitution something that is accessible to your senses? Your initial reaction ight be to say that, indeed, there is a written document that was signed by the framers of the constitution, etc... But, what if it were burned? Well, you might say, there will still be copies of the constitution somewhere. What if all the copies, everywhere, were destroyed by some unforeseen and massive-scale catastrophe? Wouldn't the US Constitution still be real? Even though you don't see it anywhere? Of course, people would still be thinking about it. So, we are back to thoughts. The point remains that, whatever real means, real is not just what is accessible to us through our senses. There are real things that are NOT accessible to us through our senses.

Besides, there are impressions given to us by our senses which are NOT real as we all can tell: For instance, when I look at myself in the mirror, I see my image 'behind' the glass. Is this real? Is there space exending behind the glass? But, I clearly see myself [well, my reflection] occupying space, as it were. You can think of many other examples: For instance, do sticks really bend when they immersed into water? They certainly look as if they were bent?

What about colors? Dim the light and your sesk does not look to be the same color anymore. What happened? Did the color change? Many students answer this by saying that the desk is still, say, brown, but it does not look that way anymore under dimmer lights. Well, think about it. Is there a REAL color of the table? Are you sure? Why should we call the brown color the real color? Why should reality depend on specific conditions - the real color is visible only when the ambient light is specifically this or that? Let's say that the carpenter made this table in the dark: is the real color of the table, then, the color which the table has in the dark? Or was the carpenter wrong about what he thought the real color of the table was? This doesn't work, as you can see. Colors are what is called in philosophy 'secondary qualities.' These qualities are not in the things themselves. To be sure, something in the thing must be producing our impressions of colors, etc., but the color is produced by the joint operation of that something and many other things - including our eye retinas, given the way human eyes are by nature. Think of taste. We say that sugar is sweet but this is inaccurate - can you now tell why? Here is an easier example: If I put my hand in the fire I experience pain. Should I then say that the 'pain' is in the fire?

What about science? Can science help out with a more commonsense response to the question 'what is real'? What sciece have to say about the nature of matter? What is the matter of the desk, for instance? Science used to say that matter is divisible down to ultimate, in-themselves indivisible, components, the atoms. Today, the scientific view is more complex - speaking of particles and energy quanta. The bottom line is this: You don't see the atoms, or the particles, or the energy, or the waves, or the electromagnetic impulses. So, science also explains what you observe BY MEANS of what you do NOT observe.

Criteria – What is Real? Can we agree on any criteria about what is real? This is not so easy. We should really do this in class - the criteria should emerge from our discussion of questions like 'are objects in my dreams real?' Here are criteria we are likely to come up with:

a) What is real must be INDEPENDENT of any one mind perceiving it. Real things are there whether anyone can perceive them or think about them or not, right? This sounds reasonable. As we will see, there is at least one major school of metaphysics - idealism - that denies this criterion or reality. So, our criteria are not acceptable by all theories. We can, and should, keep thinking about these criteria.

b) Another criterion is this: Real things must be INTERSUBJECTIVELY VERIFIABLE: more than one individuals must be able to tell that something is real. At this point, students usually start thinking 'what about my thoughts, or my feelings? Aren't they real? And yet, no one else can verify them.' Well, are you sure? What is true about this is that your emotions are private. Your thoughts are not private, as thoughts. I am not talking about the chemical reactions on your brain that go together with your thoughts - those are obviously transpiring on your brain and on your brain only. But the content of your thoughts is something you can - and do - share. We can talk about your thoughts; you can try to convince us that you are right and we can try to convince you that you are wrong. What about the emotions and feelings? Only you can verify that you have or do not have them, but you can still tell us that you do or do not have such and such feelings - so, in this sense, there is here inter-subjective verifiability. This looks like a good crterion of reality, doesn't it? If something is real, more than one minds must be able toattest to its reality.

c) PERMANENCE. Real things must last long enough to register. This becomes tricky when you start wondering how long should long enough be, but you should agree that a real thing can register on the radar of a human being's perception of what is real.

d) CONSISTENCY with other beliefs. If something doesn't fit with other beliefs we have about real things, then, this one thing seems odd. That's why very strange phenomena - if we ever experience them - make us wonder if they are real.

f) You can think of other criteria. Criteria, though, might be controversial, as I said above. Is pleasure a criterion? Do I know that something is real if it hurts to touch, for instance? This is not clear. I could be hallucinating. Here we are edging toward the next topic - philosophy of knowledge or epistemology. What about practicability? Should we say that all practically helpful/useful things are real? This is not clear at all, but there are theories that accept it as a basic criterion of what is real.

Primary / Secondary Qualities: See the discussion of colors above. What are primary qualities, then? Extension is a primary quality. Unlike color or taste, everything that is must occupy some space - no matter how small in scale that space might be. [Of course, there are religious and other kinds of beliefs about the existence of beings, like angels, who are said not to be immaterial - not occupying any space. But, notice that even for a religion that believes in angels, such beings are considered supernatural.]

What is the Ultimate Nature of Reality? –So, metaphysics studies the ultimate nature of reality. The following are theories of metaphysics. See, here, the question about life after death, below. The way you answer that question - 'is there life after death?' - tells me what theory of reality you are likely to hold. So, whether you know it or not, you do have some theory of what is real. In most classes, most students tend out to be DUALISTS - one of the theories we are examining here. Interestingly enough, this is not as commonsense a theory as MATERIALISM - and yet most students seem to subscribe to this theory and not to materialism.

Ia. Theories of Metaphysics


According to materialism, only material objects are real. Nothing can be real if it is not material. Notice that 'material' does not mean visible, audible, detectable or in any way necessarily aceessible through the senses. Indeed, there are material objects too small for the naked eye; we know that there are even material objects that are too small even for the most powerful microscope yet invented. Also, notice this: We said that science deals with unobserved real entities - atoms, particles, energy quanta, electromagnetic waves: such things are not immaterial, even though we cannot ever observe them. Can you see how this is the case?

Problems with Materialism: Materialism is perhaps the most commonsensical theory but it too has problems. a) Materialism has difficulties explaining the operations of the mind. For a materialist, all mental operations must be electrochemical events and nothing but! But, when I see a picture, the material picture - the material object out there - is somehow represented in my mind. How? Obviously, the material picture is not inside my brain. For the materialist, the representation of the picture in my brain is a chain of electrochemical events - material substances interacting, colliding, being chemically transformed, and so on. So, my ideas - perceptions and thoughts - are electrochemical events and nothing but! Every idea, for the materialist, is just an electrochemical event - and this is true of all ideas, so every idea is exactly like every other idea. All of a sudden, this does not sound all that commonsensical. How do we get from uniform electrochemical events to the whole variety of percpetions and thoughts I have in my brain? b) A second problem is this: How can a materialist account for human freedom? Human beings believe - and this is common sense - that they are free to choose what to do. Do this exercise yourself: see if you can tell why this is a problem for materialism. For materialist philsophy, events are determined by other preceding events. The fact that I have an idea in my mind - the idea that I am free to choose - is an electrochemical event; I can trace the other, antecedent, events that preceded and caused this event. So, where is the freedom? It is true that I have this idea in my head, but I do not really choose to have this idea. How would I choose anyway? Wouldn't that prior choice also have to be an electrochemical event which is also caused by an other prior electrochemical event, and so on and so on? [Of course, there are materialists who simply accept that all is determined, there is no freedom, and they find no problem with that. Others are more sophisticated - but save your appetite for when we discuss freedom later in the course. The point is that, on this issue of freedom, materialism seems to be going against common sense.]


Dualism is the theory of reality that claims that there are two kinds of real things: material things [bodies and natural objects], and certain immaterial things [minds.] Notice here, right away, that the dualists' 'mind' is not the same as the material brain - the organ on which certain electrochemical events take place. The mind is non-material. It must have something to do with the material brain but it is NOT itself material - it cannot be touched, seen, smelled, observed or sensed in any way. I can infer that it exists logically. It is immaterial. When you say that, upon dying, the body perishes but the soul or spirit or mind or whatever survives, you are most likely to be a dualist: you are saying that real things are not necessarily material. There are real things - minds, souls, spirits, or whatever - that are NOT material. [So, if you are thinking that, after death, you survive in a material form, you are not a dualist; it is also difficult to see WHAT theory you are holding - what is that thing that survives?]]

Dualism is good when it comes to explaining certain phenomena we are all familiar with - freedom of choice, mind-over-body discipline, and so on. It is, however, less commonsense than materialism - this does not mean that it is worse or better, just less commonsensical; so, it is very interesting when, in class, most people turn out to be dualists in spite of their insistence that they are down-to-earth, commonsense, practical idividuals.

Problems with Dualism: The main problem for dualism is this: How do the material and immaterial things [the bodies and the minds] interact with one another? Think about this: Material things are, necessarily, extended things - they occupy space, no matter how tiny that space is; and nothing else can occupy that exact same space. So, how and where does the immaterial mind come into the material brain? Can there be a place where they touch? But, remember, the immaterial mind is not in space - it cannot be in space, or, then, it would be material. Or, could it be that the material brain somehow has a non-material zone in which it interacts with the immaterial mind. But, then, the brain itself - the material brain - would not be altogether material - and this is illogical! Could there be something that is BOTH material and immaterial? This seems to be required by dualism. But, in that case, we are saying that there is something that both does and does not occupy space - this does not sound logical either. Or, should we say that there are things that are partly material and partly immaterial? But, then, we are back to the same problem all over again: How and where do the material and immaterial parts connect? Many philosophers prefer another solution: mind and body are identical. Well, in that case, what's the difference? Why speak of mind and body as if they were separate? Well, one possible response is this: Mind and body are two ways of speaking about the same thing. It makes better sense - we can better explain phenomena, for instance - if we use sometimes the one and sometimes the other word. I am leaving it to you, and to our class discussions, whether this is a satisfactory disposition of the interaction problem.


According to idealism, the only real things are ideas and the non-material minds that 'have' those ideas. This goes against common sense. The theory has been popular with many philosophers, but it is the one theory students resist and find implausible. Those who are poetic or artistic, sometimes, like the theory but it is not clear that they realize that this is a THEORY of what is real that we are talking about. As Russell says in one of your readings, what is fascinating about this theory is that, strange though it sounds, it can go on and on and explain even everyday life phenomena.

Problems with Idealism: Idealism appears to misunderstand what we mean when we say that we have an idea of something - for instance, a table. It is true that I cannot possibly perceive or think about the table unless I form an idea of this table. But, the idea is OF the table - we cannot say that the table is the idea. [There are other versions of idealism that are more sophisticated, but we do not study them in this course.] So, it seems that idealism confuses physical objects with the means through which we perceive them: we perceive objects BY MEANS of ideas.

Idealism faces obvious problems and embarrassments but you will be surprised how idealists are able to respond to challenges. For instance, idealism takes as a criterion of reality that real things are dependent on the mind that perceives or thinks about them. This sounds odd. Does it mean that the table is not there, is not real anymore, when there is no one around to perceive it, and when no one is thinking about it at the moment? This would have to follow from idealist premises. If only ideas and minds are real, then there is no real table when the table has no ideas of it being formed! Here is the answer idealists like Bishop Berkeley have given to this: There is nothing that does not have ideas of it being formed all the time: God has all the ideas in 'his' mind; so, there are always ideas of all things that are being formed - by the divine mind. Or, God is constantly 'obsefving' - so, forming ideas - of everything.

Another problem has to do with the criterion we put down above - the criterion of consistency: How is it we can all talk about the same table when our ideas are real for each one of us individually? The idealist answer to this is that our minds are pre-programmed - by God, let's say - so that this table right here and now had been inserted in both your and my mind-program for all eternity.

Let us review the problems faced by dualism: How is the interaction between mind and body possible?

One answer is called: Parallelism - bodies and minds - both real - are parallel; they do not interact. Each one carries 'epiphenomenal' signs that reflect or correspond to actions of the other. What do you think of this solution?

A related solution is called: Pre-established Harmony. Mind and body are indeed separate, but each one is so made, or is so by its nature, that they 'go together' as if they were directly interacting.'

Here is another attempted solution: Inadequate Concept of Causality - maybe our ways of thinking about cause and effect are insufficient when it comes to this problem - the problem of how immaterial mind causes effects in the material brain.

The solution I offered you earlier - the one that is popular - is the Identity Solution. Mind and body are just identical. a) Either the one is the 'epiphenomenon' [side effect, byproduct] of the other; b) or they are just two different words for the same thing - words we choose to better explain phenomena depending on what we are trying to describe and explain.

Electronic text of Descartes’ Meditations