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I'm trying to gain a non-trivial understanding of the Law of Identity, in Logic

I'm trying to gain a non-trivial understanding of the Law of Identity, in Logic -- what it MEANS. Is the emphasis in "Daniel equals Daniel" on the "equals", or on the two "Daniels" on separate sides of the equation. Does this law entail, for example, that if I cloned myself, I would be equal to my clone? Certainly at least in one way we are not equal - in that we take up a different area of space. If, on the other hand, it just means I am equal to myself, then why place two "Daniels" on separate sides of an equation - like the clones, they take up different space (on the page). What then is the usefulness of this law? When is it used and what does it accomplish? What does it mean for something to equal something else? And why are dialectical, continental philosophers - those heretics with the platitudinous, lazy thoughts - always trying to chip away at the iron armor of this law that seems so obvious as to need no defense? Finally, what would fall if this law fell?

The Law of Identity states that each object is identical to itself -- hard to deny. "Daniel is identical to Daniel" is a particular instance of that Law.

Your clone is not identical to you: if you and your clone we're alone in a room and we counted the number of objects in the room, we'd get two, not one.

"Daniel is identical to Daniel" does not express that the word to the left of "is identical to" is the same word as the word to the right of it: it expresses that the object the first word refers to is the same as the object the second one refers to. This can be made plainer by considering, for instance, this claim: "Daniel Defoe is identical to the author of Robinson Crusoe." This is a true identity claim, even though the words "Daniel Defoe" and "the author of Robinson Crusoe" are not themselves identical.

It would be difficult to say why the Law of Identity is true. Any defense of it would either involve using words like "equals," "same as," etc. all over again, or would use words that are themselves less clear than the word "identical." For that reason, I wouldn't understand anyone who questioned the Law. If someone said that Bob Dylan wasn't identical to Robert Zimmerman, I'd simply assume he wasn't using "identical" to express the same relation mentioned in the Law of identity.

The concept of a homunculus suggests that there is an inner core in each of us,

The concept of a homunculus suggests that there is an inner core in each of us, a "self" that makes functional and moral decisions. The emerging sciences of complex adaptive theory and network theory suggest there is no homunculus in complex living systems (from cells to the global economy). An identifiable self has not been located by neurobiologists and may never be located. The self appears to be a composite of many internal systems that interact with many external systems. If we cannot locate the self, if there is no homunculus to point to as the agent of a "good" or "bad" decision, if people are more than the sum total of their parts and cannot be reduced to a single part (such as the self), does morality still exist? That is, does the concept of morality exists if there is no concept of the self?

Suppose there were a homunculus. Would it be like me? That is, would it have conflicting motives? Foggy beliefs? Occasional weakness of will? And while we're at it, would it make any difference if the homunculus were located in one compact region of the brain? Or woud it do just as well if it were distributed over different parts of the brain, and perhaps not even clearly confined to the brain alone? What would the homunculus have to be like to do the intellectual job that's at issue? And do we really need a lot of science to know that whatever we are, we aren't simple unities?

An utter disunity isn't an agent. But think about the difference between my academic department and a random collection of professors. My department is made up of diverse individuals who don't always agree. But the department has a plan of organization, it deliberates and it acts. The members of the department co-operate to get things done, and the dissenters accept decisions of the department, once they're made, even if they aren't pleased about them. We can't say anything like this about a random collection of professors. For many purposes, my department is an agent, and it can be held responsible for what it does.

Christine Korsgaard (See her "Personal Identity and the Unity of Agency" in Philosophy and Public Affairs 18:2, 1989) argues that the unity of an agent isn't metaphysical; it's practical. We count as unified agents because we actually do manage to get past the conflicts among our motives and act one way rather than another, and because we can look at our actions from a unified standpoint. That includes things like acting on the basis of reasons and principles. This seems right quite apart from whether there's a homunculus hidden somewhere within us.

I'd add that part of what you say already gestures toward this picture. You talk about "complex living systems." We are, indeed, such things. A system isn't just a haphazard collection of processes. Systems are self-sustaining complexes that, as you point out, are more than the sums of their parts. But why isn't that good enough? Why can't the right sort of system be an agent? The homunculus wouldn't really add to the story. Indeed, as my comments above suggest, even if there were a homuculus, we might well have to tell a systems story about it anyway.

Does the individual consciousness depend on the actual atoms or only on the

Does the individual consciousness depend on the actual atoms or only on the configuration of the atoms? Suppose we have mastered cryo-freezing and atom-manipulation technology. We can freeze and unfreeze people at will. We freeze Sarah. We replace Sarah's atoms one by one. With all atoms replaced, we wake her up. Is it the "same" Sarah? (the same to herself, not just to us). Thanks, Mario

Let's call the being that results from all this replacement Sarah2. We can ask a pair of questions that seem different. One is whether Sarah2's conscious states will be like Sarah's. I agree with Mark that the answer to that question is yes; at least, it's hard to see why it would be no. But we can ask another question that seems to a different one: is Sarah2 the same person as Sarah? That's a lot more controversial.

A comparison, based on an example by Peter van Inwagen: Suppose little Johnny builds a house from a small number of blocks and leaves it in the middle of the floor. And suppose that I come in and clumsily kick the house over. If I re-arrange the blocks in exactly the same way, then the house I assemble will be indistinguishable from the one Johnny built, but it's not so clear that it's literally the same house. And if I actually replace the blocks with new ones that are just like the old ones, then it's even less clear.

So if we cryo-freeze Sarah, interrupting her normal biological and psychological processes, and then perform this massive replacement, there's at least room to wonder whether it's literally the same person. Sarah2 will no doubt think she's Sarah, but she could be wrong for all that.

This is part of a big debate, of course. One good collection that provides a wide range of background readings with a nice historical introduction is Raymond Martin and John Barresi's anthology Personal Identity, published by Blackwell.

A person with dementia is gradually losing the capacity to think and problem

A person with dementia is gradually losing the capacity to think and problem solve, remember, use language and behave as they once did. However, the person-centred approach to caring for people with dementia asserts that the 'personhood' of each person is present despite this decline in abilities. What is a person in the context of dementia and how do we understand the person who has dementia in philosophical terms?

The person centered approach to psychotherapy is a widelyused methodology. (See, for example, In contrast with some other methods, theperson centered approach leverages the patient’s own resources in therapy,rather than relying on the authority of the therapist. As your questionsuggests, this approach may seem problematic for patients with dementia. Suchpatients have diminished cognitive (and possibly affective) resources. To whatextent can such patients with contribute to their own psychotherapy? Clearly this is a matter of degree. As one’sabilities to reason, remember, and use language diminish, any form of therapywill be difficult to carry out. Person centered therapists who work with suchpatients are trained to take such limitations into account.

In philosophy there is the synchronic problem of personhood,namely what makes someone a person at a time, and the diachronic problem ofpersonal identity, or what makes someone the same person at two differenttimes. One could be a person at one timebut not the same person at some two distinct moments of time. Of course thisdepends on one’s theories of synchronic and diachronic identity as well as thenature and severity of the patient’s dementia. For example, if you hold thatliving human beings are persons (at a time and over time) in virtue of thepossession of an immaterial soul, then individuals with dementia are stillpersons at a time and over time. If you hold that an individual must have asome level and/or type of cognitive functioning (e.g. memory, language) to be aperson at a time, and must possess memories of his or her past in order to bethe same person over time, then some individuals with dementia would not countas either persons at a time or the same person over time. The problem ofpersonhood is one of the thorniest of philosophical issues, and one can’t dojustice to the range of possible answers to your question in the confines ofthis space. A good introduction to theissue is John Perry’s little book, ADialogue on Personal Identity and Immortality, (Hackett, 1978).

If an intact window is broken, is it still a window, but a broken one, or starts

If an intact window is broken, is it still a window, but a broken one, or starts to be (after the moment of fracture) a new thing?

This clearly depends on how severe the damage is. If there's a slight crack in the glass, people would still call it a window. If glass and frame are lying about, smashed into a few thousand pieces, no one (except an eccentric philosopher) would say that what's left is a window.

So how severe -- you will ask -- may the damage be exactly? This depends on standard use of the words of our language. Interestingly, things may cease under one description and continue under another. After some creative modification, what was a Hercules statue is still a statue, but not one of Hercules. After further modification it's no longer a statue at all, but still a piece of bronze. Similarly, when a caterpillar turns into a butterfly, a caterpillar ceases to exist, a butterfly begins to exist, yet an animal continues to exist throughout.

Philosophers have argued a great deal over whether what we say about such transformations is merely conventional (having to do with the words we have in our language and how we use them) or whether what we say can track (or fail to track) some truths about how matters really are (as your question seems to suggest).

Philosophers have analogously argued about the deeper issue that we tend to think of every such transformation as involving some underlying thing or substance that persists: When water turns into ice, H2O persists. When H2O disintegrates, its chemical elements (hydrogen and oxygen) persist. When these elements get transformed through a nuclear reaction, elementary particles (electrons and protons) persists. Etc. Is this just the way we think, or is this the way things turn out to be -- or perhaps the way things turn out not to be once our physics is sufficiently advanced? (Think of Einstein's formula about how matter and energy can be transformed into each other: E = mc2.)

Is there anything existing within or beyond the human body or mind that can be

Is there anything existing within or beyond the human body or mind that can be called I? If so, exactly where is I located?

Paul Bloom, a developmental psychologist at Yale, has evidence that human beings are "natural dualists," who believe that minds are distinct from, and can exist separately from, their bodies. He's just published a book about his findings, called Descartes' Baby. In addition to the scientific data he adduces, he points out that human beings universally tell stories about life after physical death, reincarnation, possession, and transmogrification (like Kafka's "Metamorphosis").

I'm not convinced by his research that we are dualists -- I think it's consistent with his data to conclude that we are functionalists -- that is, that we believe that psychology is an abstract feature of bodies. For one thing, most of these folk tales are equivocal about the physicality of the person: so even if it's stipulated that someone survives the death of their body, stories usually go on to attribute physical attributes to the "soul" -- souls are said to be located in particular places, they are said to "see" and to "hear", and sometimes to act efficaciously in the physical world. How things feats are conceived to be accomplished without bodies is left unexplained. I suspect there's deep ambivalence about the possibility of persons existing without bodies.

How do we know our right hand from our left hand when there is literally nothing

How do we know our right hand from our left hand when there is literally nothing that can be said about one which cannot be said about the other? -ace

Two important historical discussions of this problem. First, Leibniz in the Third Letter to Clarke, par.5. Interestingly, Leibniz asks whether the entire cosmos could be reversed (its handedness changed). Second, Kant, Prolegomena, par. 13, where he calls handed object 'incongruent counterparts'. In both cases, the question is on what grounds, if any, the distinction could be made.

How do philosophers decide where to draw a distinction between what one "has"

How do philosophers decide where to draw a distinction between what one "has" and what one "is". That is to say, am I the same "I" that existed before I lost a toe, or a leg, or the rest of my body, or even my brain, my mind, my thoughts, my self? Is it not logical to say that what is "me" must be distinct from what is "mine"? If this is not true, then would not "I" exist only in a virtual sense, as the image or focus of all "my" possessions?

This is a good quesiton and one that philosophers disagree about. There are three sets of issues to consider.

One is how to make sense of the persistence of anything through any change whatsoever. For example, if a tomato ripens and turns from green to red, is it the green tomato the same tomato as the red one? How can that be if one and the same thing cannot be both red and not-red? Are there some properties of an object that can alter without destroying the object, and others not? How can we make sense of that?

The second set concerns change of parts. Consider a statue and a lump of clay. It seems that the statue just is the lump of clay shaped in a certain way. But if the statue loses an arm, it seems that it is still the same statue, but it isn't the same lump of clay. Or suppose we replace the arm with one molded into the same shape out of different clay. Again, it seems that the statue can survive such a change, but the lump of clay that is the statue is not the same as the original lump. (You can ask this question also about things that aren't artifacts, e.g., over a person's lifetime their heart changes in the cells that make it up, but it continues to be the same heart.)

The third set concerns the specific problem of the identity of persons. On one hand persons seem to be just living human bodies: my existence is exactly co-extensive with the existence of this living body. But on the other hand it seems that sometimes persons go out of existence before their body dies. We also find it tempting to say of persons who go through radical psychological changes (perhaps they have amnesia or a radical conversion) that "they aren't the same person". And some find it possible to imagine that they could exist without a human body if their mental life (including their memories and other psychological traits) were transferred to another kind of body. (This idea seems to be popular in movie and tv dramas in which persons enter the body of a dog.) So it is tempting to draw the conclusion that persons are not just living human bodies, and their identity should be understood in terms of psychological continuity.

You ask, though, how do we (philosophers) resolve these puzzles? The usual way is to consider what assumptions seem to give rise to the conflict in our beliefs about the persistence or identity of something. For example, in the case of persons, we find it tempting to believe both that persons just are living human bodies, and also that persons can exist without a living human body and also a living human body can exist without it being a person. The question, then, is whether there is a way to interpret these beliefs so that they don't conflict (although they seem to), or if not, which of them we should reject.

The basic method is to look very carefully at the beliefs that seem to give rise to the puzzle and to figure out which of the beliefs (or which interpretation of them) is really important to preserve. There may be various reasons why we want to preserve a belief, e.g., it might be that we have very good empirical evidence for it. Or it might be that it plays an important role in our thinking about morality or law. Once you've carefully selected and defined the really important beliefs, see if the puzzle remains. If it does, look again to determine whether the beliefs can be adjusted in ways that preserve what is important about them, but also avoids contradiction with the other important beliefs.

I'm sure this seems very abstract. But in the sort of case you describe, I think some changes in persons are changes in properties that can be handled by being sensitive to time and tense: I was shorter when I was a child than I am now. Other changes (like losing a toe or a leg) are perhaps similar to the statue and the lump of clay: I am more like the statue (or the heart) than the lump. And changes so drastic that they involve a loss of mind are ones we don't accept because the notion of a person is partly a forensic notion, i.e., concerned with responsibility. If what is important about persons is that they are agents in the world that can be held responsible for their actions, then to say that something is a person but has no mind undermines the very point of having the concept of person at all. Or, if this isn't what's important about persons, your task is to figure out what is.

Alexander George has made a distinction between the brain making a decision and

Alexander George has made a distinction between the brain making a decision and "I" making a decision (see I'd like to know what exactly he means by "I" if not the brain. Unless the flesh of our bodies thinks, then it seems perfectly acceptable, if not more accurate, to say the brain makes all decisions. What more can he be referring to that is not contained within the brain?! Not only that, it seems that the brain is doing all this decision-making automatically since there is nothing outside our own brain that we can use to control it. I believe a good and simple answer to the original question, (to paraphrase) "How am I responsible for my decisions when it's my brain that makes the decisions"? is to say that the "I" IS THE BRAIN.

I am now typing. My brain isn't typing. Nor are the tips of my fingers, though I am typing by having them strike the keyboard. I am typing. You ask who this "I" is if not my brain. It's me, Alexander George. If this is acceptable, then we (you and I) can turn to decisions.

Could I have been my sister?Thanks, Bob.

Could I have been my sister? Thanks, Bob.

Try this question: Could you have been your sister and your sister been you and everything else been pretty much as it is? I find it kind of hard to get my mind around that: In what precisely would it consist that you were her and she were you? There are certain conceptions of the soul that would make sense of that: Your soul would occupy her body and hers would occupy yours. But even those philosophers attracted to a notion of soul have usually thought the soul was more intimately connected to the body than that: If we accept that kind of possibility, who's to say souls aren't switching bodies every time someone falls asleep?

So suppose we agree that isn't possible. Now it clearly is possible that she should have existed without you. But could it have happened that you should have existed without her but, so to speak, as her? What on earth is that supposed to mean? Either she exists or she doesn't, and if she doesn't exist, then you can't be her. (Perhaps you could have looked like her and acted like her and so forth, but that isn't what's at issue.)

But we can try to imagine that possibility a different way: Could you both have existed but been the same person? (This is Peter Lipton's question.) That one's not so clear to me. A case that might seem plausible would be that of identical twins. So here are Don and Dan, separate persons only because the blastocyst from which they were formed split early in its development. Suppose it hadn't split. What, then, should we say about Dan and Don? Would they have existed? It seems difficult to suppose that only one of them would have existed: Which one? But maybe it also seems difficult to suppose that neither of them would have existed, and, if so, then perhaps one should conclude that both of them would have existed but been the same person. But of course that's a special case, and one that probably doesn't apply to you and your sister.