Leibniz'sprinciple of the indiscernibility of identical is often used as a means to demonstrate that mental states and brainstates can not be identical.
Some technical remarks in advance. Qualia is the plural of quale, which means the subjectivity of our sensory experiences.
A valid logical reasoning leads to a conclusion that is true, if and only if the premises are all true.
The symbol ≠ means IS NOT IDENTICAL WITH.
The remainder of this lecture are not my words but the words of Patricia Churchland, as quoted from her book "Neurophilosophy", 1986.
This lecture will be longer than usual, but you really have to hear this and maybe reread it later, because it is a brilliant example of logical and philosophical analysis regarding Leibniz Law and theIdentity Theory.
( A )
( 1 ) The qualia of my sensations are knowable to me by introspection .
( 2 ) The properties of my brain states are not knowable to me by introspection .
(3 ) The qualia of my sensations ≠ the properties of my brain states .
A second argument , complementary to the first , seems also in play :
(1) The properties of my brain states are knowable by the various external senses .
(2) The qualia of my sensations are not knowable by the various external senses .
(3) The qualia of my sensations ≠ the properties of my brain states .
The general form of the argument seems to be this :
(1) a is F
(2) b is not F
(3) a ≠ b
Leibniz 's law says that a = b if and only if a and b have every property in common . So if a = b, then if a is red, b is red, if a weighs ten pounds , then b weighs ten pounds , and so forth . If a is red and b is not , then a ~ b.
Assuming their premises are true , arguments (A ) and (B) appear to establish the nonidentity of brain states and mental states . But are their premises true ?
Let us begin with argument (A). There is no quarrel with the first premise (the qualia of my sensations are known -to-me-by-introspection ), especially since qualia are defined as those sensory qualities known by introspection ,
and in any case I have no wish to deny introspective awareness of sensations . In contrast , the second premise (the properties of my- brain states are NOT known-to-me-by-introspection ) looks decidedly troublesome.
Its first problem is that it begs the very question at issue - that is, the question of whether or not mental states are identical to brain states . This is easy to see when we ask what the justification is for thinking that premise true .
The point is this : if in fact mental states are identical to brain states, then when I introspect a mental state , I do introspect the brain state with which it is identical .
Needless to say, I may not describe my mental state as a brain state, but whether I do depends on what information I have about the brain , not upon whether the mental state really is identical to some brain state.
The identity can be a fact about the world independently of my knowledge that it is a fact about the world . Similarly , when Jones swallows an aspirin , he thereby swallows acetylsalicylic acid, whether or not he thinks of himself thus;
when Oedipus kissed Jocasta, he kissed his mother , whether or not he thought of himself thus . In short, identities may obtain even when we have not discovered that they do.
The problem with the second premise is that the only justification for denying that introspective awareness of sensations could be introspective awareness of brain states derives from the assumption that mental states are not identical with brain states.
And that is precisely what the argument is supposed to prove . Hence the charge of begging the question . (Although I have used (A) as an illustration , the same kind of criticism applies equally to (B).)
Other problems with these arguments are more subtle. One difficulty is best brought out by constructing an argument analogous to (A) or (B) with respect to the character of the properties under discussion and comparing the arguments for adequacy. Consider the following arguments :
(1) Smith believes Hitler to be a mass murderer .
(2) Smith does not believe Adolf Schicklgruber to be a mass murderer .
(3) Adolf Schicklgruber ≠ Adolf Hitler .
As it happens, however , Adolf Schicklgruber == Adolf Hitler , so the argument cannot be right . Or consider another instance of the general argument form where the property taking the place of F is a complex property concerning what John believes or knows :
(1) Aspirin is known by John to be a pain reliever.
(2) Acetylsalicylic acid is not known by John to be a pain reliever .
(3) Aspirin ≠ acetylsalicylic acid.
And one final example more closely analogous to the arguments at Issue:
(1) Temperature is directly apprehensible by me as a feature of material objects.
(2) Mean molecular kinetic energy is not directly apprehendable by me as a feature of material objects.
(3) Temperature ≠ mean molecular kinetic energy.
These arguments fail because being-recognized-as-a-something or being-believed-to-be-a-something is not a genuine feature of the object itself , but rather is a feature of the object as apprehended under some description or other or as thought about in some manner.
Having a certain mass is a property of the object, but being-thought-by-Smith-to-have-a-certain-mass is not a genuine property of the object. Such queer properties are sometimes called " intentional properties" to reflect their thought-mediated dependency .
Notice that in (B) the property is being-knowable-by-the-various -external-senses, and in (A) the property is being-known -by-me-by-introspection . Both are sterling examples of thought-dependent properties .
Now the arguments (C) through (E) are fallacious because they treat intentional properties as though they were genuine properties of the objects, and a mistake of this type is called the intentional fallacy.
It is evident that the arguments designed to demonstrate the nonidentity of qualia and brain states are analogous to arguments (C) through (E).
Consequently , they are equally fallacious, and the nonidentity of mental states and brain states cannot be considered established by arguments such as (A) and (B).
[13:29] herman Bergson: Whips his forehead.....
[13:29] herman Bergson: phew...
[13:29] herman Bergson: Thank you....
[13:29] Bejiita Imako: hehe
[13:30] :: Beertje :: (beertje.beaumont): whips her forehead too...
[13:31] herman Bergson: the main point of the lecture is that thought dependent properties like knowable to the senses are treated as properties of real objects , like weight and mass are such properties
[13:31] Mick Nerido: So we have mental states and brain states that cannot be proven identical?
[13:31] herman Bergson: And I found this extensive quote too beautiful and clear that I didn't want to rephrase it
[13:32] herman Bergson: No it is the other way around...
[13:32] herman Bergson: the fact that I know what it is like to feel my toothache , and I only can know it,
[13:33] Bejiita Imako: aaa like that if i think a thing work a certain way that doesn't mean that is the way it really works but how I THINK it works
[13:33] Bejiita Imako: I get everything right
[13:33] druth Vlodovic: I'm sure I could hook up some sort of detector that would tell me about your toothache
[13:33] herman Bergson: while all dentists in the world can see the hole in the tooth and the infected nerves, whci make then conclude:this is a toothache, means that these to things are not identical...
[13:34] druth Vlodovic: well, maybe not me personally
[13:34] Bejiita Imako: because the dentist cant feel your pain
[13:34] herman Bergson: Yes Druth, but the claim is that YOUR personal knowledge of the pain can only be YOUR personal knowledge....
[13:35] Bejiita Imako: only see and conclude that OUCH that gotta hurt!
[13:35] herman Bergson: so that is an EXTRA property which never can be detected by whatever tool or microscope
[13:35] Mick Nerido: My personal mental state is identical to my brain state...
[13:35] herman Bergson: Yes Mick....
[13:35] Bejiita Imako: you cant connect another persons senses to a osciloscope and measuring device that you can do with signals from ect a computer
[13:36] druth Vlodovic: can't we?
[13:36] Bejiita Imako: and get the exact meaning of that signal
[13:36] Bejiita Imako: the way I feel it
[13:36] herman Bergson: No Bejiita...we can not observe the subjective quality of an experience...
[13:36] druth Vlodovic: ah, the interpretation you mean
[13:37] Bejiita Imako: with a computer i can transmit data from one device to another for ex an mp3 in my computer can be transfered to my mp3 player and it will play exactly the same as my computer
[13:37] herman Bergson: but this subjective aspect is thought dependent, so added to the object by thought...not a physical property of the experience itself
[13:37] Mick Nerido: You bring all your personal history to every perception
[13:37] Bejiita Imako: that you can't do with the senses
[13:37] druth Vlodovic: sim suggested once that the mind could be thought of as the result of processes, solves a lot of problems
[13:37] Bejiita Imako: transfer another persons feelings to you so you can feel them as well
[13:38] Bejiita Imako: or what that person thinks
[13:38] Bejiita Imako: is impossible
[13:38] druth Vlodovic: you'd have to be able to duplicate all of the current processes in order to duplicate the specific eexperience
[13:38] herman Bergson: that is the problem Druth, for that isn't true...
[13:38] herman Bergson: I could duplicate you..but then there is a Druth 1 and a Druth 2
[13:38] druth Vlodovic: oh?
[13:39] Bejiita Imako: yes
[13:39] herman Bergson: so Druth 2 will only have Druth 2 experiences....
[13:39] Mick Nerido: Like our favorite songs have a different meaning to us than others...
[13:39] herman Bergson: Druth 1 will never experience what Druth 2 experiences
[13:39] Bejiita Imako: with a computer its possible as long the 2 cpus can process exactly the same data in exactly same way
[13:39] druth Vlodovic: but if both druths had the exact same processes going on then they would be having the same experiences
[13:39] Bejiita Imako: the 2 will read the information the same way
[13:40] druth Vlodovic: only the differences between them would prevent them having identical experiences
[13:40] Bejiita Imako: not possible with the mind between 2 persons
[13:40] herman Bergson: No Bejiita....there always is the difference caused by the individuality of Druth 1 and 2
[13:40] herman Bergson: Yes Druth….that is what the arguments (A) and (B) claim
[13:40] Bejiita Imako: and also no way to transfer from one mind to another, there is no "interface" that can do that isn the same way ex an usb port on your computer can
[13:40] druth Vlodovic: yes, if one cpu is slower or produces a different amount of heat then they are not identical
[13:41] herman Bergson: But that is only the case when you say that this personel feature of the experience , these qualia are properties of the mental states...
[13:42] Mick Nerido: When 2 people read the same newspaper the info therein is identical
[13:42] herman Bergson: But I claim that thought adds these properties to the mental state….
[13:43] Bejiita Imako: id say tat the biggest ting that it is impossible is because there is no way to transfer the exact mind information to another person in the way digital data is transferred from one computer to another, that's why mind reading is impossible
[13:43] herman Bergson: Well some of you collapsed already during the lecture.....
[13:43] herman Bergson: It was an experiment to put you all through this...
[13:44] herman Bergson: At least you have seen an example of professional philosophical analysis and the use of logic...
[13:44] Bejiita Imako: it was advanced complex but very interesting and i think i got a grasp of what it was all about
[13:44] Bejiita Imako: ㋡
[13:44] herman Bergson: I would suggest, if you want to get a better grip on it, read the blog ...
[13:45] Bejiita Imako: have to read on it some more indeed
[13:45] Bejiita Imako: lot of things
[13:46] Bejiita Imako: but as i see it i conclude it all means that because i think a thing is in a certain way that doesnt have to mean its the true state its simply what i believe it to be
[13:46] herman Bergson: The theme of the text is pretty clear....the arguments have fallen victim of a fallacy and thus dont prov ethat brain states and mental states can not be identical
[[13:46] herman Bergson: I have to watch my tongue!
[13:46] Bejiita Imako: haha
[13:46] bergfrau Apfelbaum: hmm? why we fall?
[13:46] Bejiita Imako: i still use the fall thing from Burn
[13:46] Bejiita Imako: its damn funny
[13:46] Qwark Allen: °͜° l ☺ ☻ ☺ l °͜°
[13:46] Qwark Allen: lol
[13:46] bergfrau Apfelbaum: omg
[13:46] Bejiita Imako: lol
[13:46] herman Bergson: I hope you enjoyed it yet...
[13:46] :: Beertje :: (beertje.beaumont): lol
[13:46] bergfrau Apfelbaum: was ist das?
[13:47] bergfrau Apfelbaum: the wort fall?perhaps
[13:47] bergfrau Apfelbaum: haha
[13:47] bergfrau Apfelbaum: jaaa
[13:47] Bejiita Imako: yes
[13:47] herman Bergson: Next time I'll be more gentle again to your minds
[13:47] Bejiita Imako: hehe
[13:47] Qwark Allen: fall
[13:47] druth Vlodovic: nah, we can take it
[13:47] Qwark Allen: was very good discussion
[13:47] Bejiita Imako: hahaha
[13:47] druth Vlodovic: we'll wear tinfoil hats to cool our overworked minds
[13:47] herman Bergson: So i See....lol
[13:47] Bejiita Imako: ㋡
[13:47] bergfrau Apfelbaum: yey! herman
[13:47] bergfrau Apfelbaum: ty so much
[13:47] bergfrau Apfelbaum: ***** APPPPPPPLLLLAAAUUUSSSSEEEEEEE***********
[13:47] Qwark Allen: got to read the all thing again
[13:47] Bejiita Imako: HoOOOOOOoooooOOOOOooooOOOOooooOOOOoOOOOooooOOOOooOOOOooooOOOOooooOOOO..!!!! HAHAHAHAHAAHA
[13:47] bergfrau Apfelbaum: Yeah!!!!!
[13:47] Mick Nerido: Thanks herman!
[13:47] Bejiita Imako: awesome
[13:47] Qwark Allen: ¸¸.☆´ ¯¨☆.¸¸`☆** **☆´ ¸¸.☆¨¯`☆ H E R MA N ☆´ ¯¨☆.¸¸`☆** **☆´ ¸¸.☆¨¯`
[13:47] Qwark Allen: thank you
[13:48] herman Bergson: Thank you for your participation…..Class dismissed ㋡
[13:48] Bejiita Imako: ㋡
[13:48] Bejiita Imako: oki cu soon
[13:48] bergfrau Apfelbaum: byebye class :-)) so u on tuesday
13:48] druth Vlodovic: have fun herman, and thanks fro the lecture
[13:48] :: Beertje :: (beertje.beaumont): thank you Herman...het was een pittige les!
[13:48] bergfrau Apfelbaum: danke hermaaaaaaan bussi :-)
[13:48] Qwark Allen: ˜*•. ˜”*°•.˜”*°• Bye ! •°*”˜.•°*”˜ .•*˜ ㋡
[13:48] Qwark Allen: i have to go to a partyy
[13:48] herman Bergson: Yes Beertje I was well aware of that
[13:49] :: Beertje :: (beertje.beaumont): needs a glas of wine now...
[13:49] bergfrau Apfelbaum: #°*** BABA ***°#
[13:49] herman Bergson: I guess so!