[Music] hello class today we're going to be discussing the first half of the first day of john perry's dialogue on personal identity and immortality here's some study guide questions to help us get started one who are our characters two what does y rob want miller to do three what are two strategies for showing something is possible four what is miller's first attempt to answer why rob five what is the point of the analogy with the tissue box six what is the difference between qualitative identity and numeric identity seven which two inferences are supported by qualitative identity all right those are our study guide questions and as the video proceeds you'll want to write down the answers or type them up or crochet them into a sweater or do whatever it is that you're doing to record the information these are not something that you need to turn in but they are a helpful way to compartmentalize and organize all of the information that we're going to review in this course in this dialogue by john perry we begin with three interlocutors three characters who are going to be speaking to each other about philosophical matters over the course of the entire dialogue first there is gretchen weirob wyrob is an atheist and she is also dying she'll be dead very soon and all of the characters acknowledge this some politely some less politely at the very outset secondly there's also sam miller sam is a christian he believes that wyrob's death will not be the end of her personhood and then there is dave cohen a jewish man who also believes that wyrob may have an afterlife in store for her but doesn't share the same perspective as sam now at the very outset right after everyone acknowledges that wyrob will be dead soon she says that what she'd like to do in her last few living hours is to have a rigorous philosophical discussion that's her favorite thing to do she is a philosopher and so she'd rather go out doing that than anything else based on the circumstances they decide to talk about the afterlife and whether it makes sense at all to suppose that death is nothing more than the complete end of gretchen wyrop sam miller believes in an afterlife he believes that gretchen wyrob will live on in some sense some yet to be specified sense whereas gretchen weirob doesn't think this at all they decide this for their topic and they immediately begin to talk about the idea of survival why rob clarifies that for there to be really such a thing as the afterlife for her to really in some sense survive her death even though that's strictly a contradiction if i tell you that a plane crashed and everyone died it doesn't make sense to ask about the survivors surviving means that you didn't die but putting that aside here's what y robb wants miller to do she wants miller to show that it's possible for a person to exist after why rob's death whose experiences why rob can look forward to having she wants miller to show that it's possible for her to anticipate more experiences after her death miller of course balks at this and says what do you mean show that it's possible just imagine that it happens imagine that you die and then there you are how what else is there to do and here is a good time to talk about what why rob is really asking for why rob wants miller to show that something is possible now that's a very strange sort of question because ultimately a thing's being possible is kind of the default unless there's some reason to think that something is impossible you should assume that it's possible in general when faced with some proposition the burden of proof is for someone to show that that proposition couldn't happen that it can't be the case rather than having to show that it could be so when philosophers want to know that something is possible they often express this by also supplying a reason for thinking that it's not so philosophers will say how can people enjoy tragedies given that they make us sad how is it possible for material objects to exclude each other given that each material object is co-located with its matter how is it possible to choose what you know to be bad given that every choice is directed at the best option when philosophers want to know how something is possible they'll ask how is x possible given that why and that's actually what y rob does here she asks how is it possible for a person to exist after my death whose experiences i can look forward to given that my death consists in the dissolution of my body she points out that once she's dead she will be interred that she will rot that she will disintegrate or if she's cremated she will be burned away she will be gone given that she will be gone how is it possible for there to be then a person later who is her how is it possible for wyrob to anticipate postmortal experience given that her death means that she won't exist now when philosophers are tasked to show that something is possible to show that despite some consideration it could actually happen there are two strategies for doing this one way to show that something is possible is to show that it can be clearly imagined show that it is imaginable in other words you can often show that something is imaginable by drawing a picture or a diagram or describing it in a very vivid way so if someone asks how it's possible for there to be a three-dimensional shape with only one side you could show them a mobius strip or if someone asks how it's possible for three grains of sand to make up a heap you draw a diagram that shows one grain of sand and another grain of sand and a third stacked on top to make a little heap sort of shape that's one way to show that something is possible is you show that it can be clearly imagined that it can be vividly pictured in other words now one limit on this method is that not everything you can picture is actually possible for instance thanks to the brilliant work of m.c escher we can vividly imagine a staircase in three-dimensional space that is always going upward and curving in on itself that is clearly imaginable but it's not actually possible that can't exist in three-dimensional space now the other way to show that something is possible is to show that it's conceivable to show that you can make sense of it in other words and the way that you do this is to give a clear account of it to give a clear explanation of its workings in a way that does not involve any contradiction or absurdity as an example ask this question is it possible for a white egg to have exactly 10 000 little red spots on it that seems possible why couldn't there be such a thing but now ask are you able to clearly envision such a thing can you count all ten thousand of the spots in your imagination and make sure that they're exactly ten thousand probably not and it would also take a while to draw one and let's be honest you wouldn't need to draw one in order to know that it's possible how do you know that it's possible then well you make sense of the idea you can talk your way through this idea that you have an egg with certain surface area and there's little speckles that could go on it which are so small that you could have ten thousand of them on there and no more once you describe it and establish that there's no contradiction in that description or any other absurdity there that's a reason to think it's possible now while this method is not absolutely infallible most philosophers agree that conceivability is a better guide to possibility than imaginability so those are the two ways to try to show that something is possible so that it's imaginable or show that it's conceivable and then we get miller's first strategy for showing that why rob's afterlife is possible miller goes for imaginability miller says imagine that several thousand years from now two people meet i am one of them you are another one there we imagined it it's so it's clearly possible what is impossible about that why rob again reminds miller that she will have already disintegrated she will have already died and that's the reason to think that that situation though imaginable is not really possible she then emphasizes the point by mentioning a tissue box with a certain brand name she points out that if she were to take this specific tissue box and burn it there's no way that that tissue box that very one could be the same tissue box as some other one that comes along later miller objects sure there could it could be identical in every respect it could be exactly like it and why rob chides miller for confusing things let's not follow miller and be confused ourselves there are two separate notions at work here both related to the idea of identity let's distinguish between qualitative identity and numeric identity qualitative identity is exact similarity that's what qualitative identity is exact similarity a and b are qualitatively identical as long as a and b are exactly similar they have exactly the same features they resemble down to the finest detail that's what qualitative identity is qualitative identity is very very close or exact similarity when we say that identical twins are identical we mean that they're qualitatively identical when a number of golf balls come off of the golf ball factory and they all look exactly alike we could say that each one of those golf balls is qualitatively identical to the next note that many distinct things can be qualitatively identical or at least most philosophers think so leibniz and a few of his followers didn't check out the first video on this channel as a matter of fact i covered this topic contrast that with numeric identity numeric identity is the relation that each thing bears to itself no two things can be numerically identical if they were numerically identical what we would have is one thing for example mark twain is numerically identical to samuel clemens they're not two different people mark twain and samuel clemens they're exactly the same person there's only one guy two different names but one person that's what it means to say they are numerically identical note that grammar is constraining me to use the plural here but one thing each thing is numerically identical to itself no thing is numerically identical to any other thing you could say numerically identical to means the same thing as one and the same as note that numeric identity entails qualitative identity each thing that exists is exactly like itself at any given time nothing can be taller than itself at the very same time or bigger than itself or smaller than itself or a different color than itself at least if you're talking about the very same part of the thing at the exact same time but qualitative identity does not entail numeric identity from the fact that a and b are exactly alike it doesn't follow that there's just one object which is both a and b no you could have two things that are exactly alike philosophers are interested in numeric identity because there are two sorts of inferences two kinds of conclusions you can draw that involve numeric identity one of them is the following a has feature f a is numerically identical to b therefore b has feature f that is an inference supported by numeric identity and it makes sense if mark twain drinks several whiskeys every day and if mark twain is the same person as samuel clemens well then samuel clemens drinks several whiskeys every day as because they're the same guy it just follows from the fact that they're the same guy if mark twain wears a white suit and mark twain is samuel clemens that means samuel clemens wears a white suit and so on this gets interesting in philosophy when we start to have arguments like this a human being is just their body human beings can be virtuous so human bodies can be virtuous the other sort of inference that numeric identity supports is this one a has feature f b does not have feature f therefore a is not numerically identical to b they are distinct this one should also make sense if you think about cases if the evil pirate is a one-handed man and peter is not a one-handed man then the evil pirate is not peter and we can in fact use this second inference to show what is wrong with miller's first attempt to convince wyrub of the possibility of the afterlife the future person miller describes has not rotted away or disintegrated they're right there integrated but why rob would have disintegrated and so they're not the same person now it's at this point in the first day of the three-day dialogue that miller begins to describe his mind-body dualist view which is connected to his christianity he begins to talk about the idea of a soul and that's where we'll pick up with the next video for this week i'll see you next time when we finish up day one of perry's dialogue on personal identity and immortality two [Music] you