If a person has a multiple personality disorder, are they one individual, or several individuals?

What used to be called multiple personality disorder (MPD) is now called dissociative identity disorder (DID) in DSM, the Diagnostic and Statistical Manual of Mental Disorders , and the change in terminology may reflect a possible change in thinking. A personality (e.g. a television personality) is in one sense a person, but generally I and my personality are not the same (Same what? Same entity, presumably, if that is any help!) In any case, since my personality might change considerably over time, while I remain the same person or the same individual (I assume that individual and person , as they are applied to human beings, are equivalent concepts), the two cannot be identical. And most of us do exhibit slightly different personalities, for example at home and at work, or with friends and with superiors. Those who have a mixed ethnic or national heritage can sometimes find that they have two personalities, say one English and one Indian. They may...

I am a humanities teacher teaching Philosophy around the question of what does it mean to be human? I am hoping to find some age appropriate readings/ videos that discuss the basics of the philosophical movement. Can anyone help me? Thanks

How about Leslie Stevenson's Ten Theories of Human Nature ? I have had good luck teaching freshmen with this, doing a course called "Human Nature". It's on Amazon at http://www.amazon.com/Ten-Theories-Human-Nature-ebook/dp/B003F3PN1K Good luck with the class!

Philosophers debate persistence conditions for personal identity because everything about us seems to change, including our cells, our memories, and our bodies. But DNA doesn't change and it codes for specfic traits in every cell of the human body. It's true that we experience changes in the way phenotypes are expressed in particular experiences or memories, but why not conclude that DNA is the ultimate source of personal identity? Philosophers don't seem to give this biological candidate serious consideration. Can you tell me why?

DNA does change. There are "point mutations", for example, in which say a single nucleotide changes, say from guanine to cytosine. . . . CTG TCA . . . becomes . . . CTG GCA . . . If there is a strand of DNA that suffers such a change, is it then not the same strand of DNA ? This is exactly like the question whether persons become different persons if they lose say half a finger. And now we have the problem of DNA identity. When are two descriptions sufficiently similar to count as descriptions of the same strand of DNA ? Anthony Quinton has the general issue right, in a 1962 article in the Journal of Philosophy called "The Soul": 'No general account of the identity of a kind of individual thing can be given which finds that identity in the presence of another individual thing within it. For the question immediately arises, how is the identity through time of the identifier to be established? It, like the thing it is...

Hello Philosophers! Can anyone defend the Ontological Argument against Kant's criticism that existence is not a predicate?

Some random suggestions: (1) David Pears pointed out that even if Kant's argument were wholly clear and wholly successful, which it is not, it could only show that existence is not an ordinary predicate, if it is a predicate. His view is that it is a predicate, just a very peculiar one; (2) There is also the view of the celebrated logician, mathematician and philosopher Bolzano, who writes in the Theory of Science ("Kinds of Propositions") that 'I take being [Sein] or actuality [ Wirklichkeit ] to be precisely what language makes it out to be, namely an attribute; whoever denies this confuses (I believe) actuality with substance. By substance I mean an actuality which is not an attribute of another actuality; hence I admit that we cannot truly predicate the putative abstractum of the substance (substantiality) of any object. For it is part of the concept of substance that there is no property of this kind. But it is not the same with actuality, which I consider to be a mere attribute, not...

When I see a pink ice cube, then I see a coloured three-dimensional material object; and it seems to me that its colour is equally spatially extended. But isn't it a category mistake to speak of three-dimensional colours rather than only of three-dimensional coloured objects? Aren't all properties simple and adimensional entities? The ice cube's pinkness isn't like a gas that can fill up a volume of space, is it? Is its seeming three-dimensionality a phenomenal illusion?

You are absolutely right. Neither colour nor a colour is spatially extended, and a colour like pink is exactly not like a gas that fills up a volume or spreads itself, perhaps very very thinly, over a surface. That is a category mistake. Nor do colours have thicknesses. I am delighted to see a recognition of this important point, to which I have found very little attention paid in the literature on the philosophy of colour. Though I tried to get started sorting out the tricky logic of "pure" colours, as Wittgenstein calls them (to be contrasted not with impure colours but with things coloured the colours), in Chapter 7 of Colour: a Philosophical Introduction , published in 1987 and 1991, but that was only a beginning. Consider two patches of the same red, patch A surrounded by green and patch B surrounded by red. We can say that the colour of patch A is identical with the colour of patch B. But then as G.E. Moore pointed out (in his early paper on "Identity") it follows, or seems to,...

Is all truth subjective? A subjective truth is a truth based off of a person's perspective, feelings, or opinions. Everything we know is based off of our input - our senses, our perception. Thus, everything we know is subjective. All truths are subjective. Do you think all truths are subjective? If not, what is wrong with the above argument?

Your argument is: (1) Our senses and perception are subjective. (2) Everything we know is based on on our senses and perceptions. Therefore (3) Everything we know is subjective. There is a well-known difficulty with this argument. It equivocates on "subjective". In the first premise "subjective" means something like the innocuous "possessed by a subject", but in the conclusion it is presumably taken to mean the toxic "not having any objective truth". There is also a doubt about the second premise. Many philosophers accept the idea of "a priori" truths, that is, truths that hold independently of experience, including mathematical truth and perhaps ethical truths, if there are any.

Is the concept of backward causation coherent and is it really taken seriously by philosophers? I doubt whether any scientist would accept the idea and I would like to know what you think.

Is the idea of backwards causation coherent? It seems not, as you could, for example, cause earlier events, such as your own birth, not to have happened. There is also the famous "bilking" (cheating) argument due to Max Black, according to which you can prevent the future cause of something that has already happened from occurring. All the same, philosophers, particularly Michael Dummett, have taken the idea perfectly seriously, and defended it. You write that you doubt that a scientist would take the idea seriously, but plenty of physicists, including Richard Feynman, have indeed used the idea for a variety of purposes, including the remarkable idea of positrons running backwards in time.

About philosophy of color: It's very interesting but I'm having trouble understanding it because most of the works I encountered aren't "beginner-friendly". My question is, what exactly is color relationalism and what does this have to do with phenomenology? Thank you!

Colour relationalism tells us that colours are relations between perceivers and the objects that they perceive. (This gets a bit tricky of course if what they perceive is a colour, because then what they perceive is a relation between themselves and a relation between themselves and a colour, or rather, a relation between themselves and a relation between themselves and a relation between themselves and a colour.) "Colour phenomenology" doesn't mean an awful lot: just the (apparently) obvious facts about colour and classifications of things having to do with colour based on these facts. Phenomenology in this sense has seemed to oppose colour relationalism. We don't seem to see relations between ourselves and tomatoes when we see red tomatoes. What we see is a property flattened on to the surface of the tomato! So colour relationalists have to work a bit to square their view with the phenomenology. Without meaning to be rude, might I inquire whether this is an essay topic you have been set? Why are you...

I hope this is not too general of a question, but the more I thought about it the more I realised it was a very difficult question to answer. It does not necessarily pertain to anything religious, but I believe in a God who is eternally good, just so you know the angle that I'm coming from. Anyway, here is my question: Would the idea of something or someone being truly 'good' have ever come about if it never had the contrast of something 'bad' or 'evil' to compare it to? Hypothetically speaking, if someone were to never experience anything bad, would they ever have the understanding of something being good?

What you describe is one response (one that has occasionally been used by theists) to the problem of evil. It is sometimes called the "contrast" argument. It is found for example in Leibniz's Theodicy of 1810, in various forms, along with other arguments defending theism. The version that you propose is that evil must exist for there to be an understanding of good. In some versions of the contrast argument, evil must be there if good itself is to exist. I think it is possible however to have a very good understanding of something positive (the positive numbers, for example) without understanding something negative. Again, I can perfectly well enjoy a good ice cream without ever having tasted a bad one, and know that it is good, at least in the sense that I enjoy it. I don't think that I myself have ever had a bad ice cream, rather than the odd less than perfect one, though I may be wrong, but in any case my enjoyment of all the good ones would be much the same even if I had had a bad...

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