The Copenhagen view was this yes in quantum mechanics the physicist is building models of the phenomena but he only builds a model of what's on the other side Beyond his instrument there's always this dividing line that he only makes a model of what is beyond the instrument now if he wants to model the instrument too fine but then he steps one step back and defining lines a Bit closer that's all okay so that means that we cannot have her we can never think that the world is a quantum mechanical system because there's no dividing line
anymore if you say that right so this was the point there point of view their um you know Observer it's always Observer relative hello this is Robinson Erhardt here with the introduction to Robinson's podcast Number 125 and this episode is with boss Von frassen who is the makash professor of philosophy Emeritus at Princeton University and also a distinguished professor of philosophy at San Francisco State University boss as I think I may mention a couple of times in the episode is a legend in the philosophy of science though he's also done a lot of work in
other areas as well notably epistemology and logic and both of those subjects make their Appearances in our discussion as well but the focus of the conversation or the episode is rather esoteric and is in this sense I think fair to say it's a a throwback to the pure philosophy area of this show which I think of maybe as episode 30 to 99 and we talk about a shift in the philosophy of science in the second half of the 20th century from the view of The Logical positivists on the one hand like Reichenbach and karnap who
had a very formal mathematical Approach to the philosophy of science two philosophers who adopted the semantic approach which more closely aligns with or aligned with how working scientists viewed and experienced the field so along the way we touch on a number of other major issues in the philosophy of science that were raised around the same time including the question of scientific realism boss is well known as a scientific anti-realist Thomas Kuhn and his book The structure of scientific realism and then the various interpretations of quantum mechanics I should also say that many of you have
noticed that Robinson eats is no more and while this is true I can assure you that Robinson still eats however and if you ever join me as I ate thank you and I just finished a pint of lemon curd ice cream in your honor so I should also mention that likes comments subscribes these are all endlessly appreciated and Then of course there is this this shirt I'm wearing which you can find at Robinson's fashion Empire which can itself be found either at robinsonsfashionempire.com or at robinsonairheart.com now without any further Ado I hope you enjoy this
conversation as much as I enjoyed having it with boss thank you foreign boss you you have a very long and storied career in the philosophy of Science and I'm wondering how just how it started was that always your main interest in philosophy no no it's um it wasn't but it was it came pretty quickly so you know I I got interested in high school I was working uh part-time in the public library and reading all the stuff I could find going around in around philosophy um and I thought that yoga was a sort of a
philosophy Etc you know I got a little Confused obviously to begin but then I read a dialogue by Plato the final and that really opened my eyes to what it could be but so you know that's pretty far from philosophy of science and I thought that I might maybe combine literature and philosophy but then in University my second year I was working part-time in the University Library they were taking the same opportunity to Find books right and I came across reichenbos philosophy of space and time that really had a great great impact on me um
I found it absolutely fascinating um I mean I could that philosophy of science philosophy could be done that way philosophical science could be done that way in this you know very professional interesting way where you really went deeply into the theories So that's the other side of me we are we we both spent a lot of time in libraries and working part-time in the public libraries a great way to get started in Academia but just to clarify when you're saying that you liked the way that Reichenbach did philosophy of science and he got deep into
the theories you're saying that you were very interested in a philosophy of science that took science itself very seriously and wasn't just armchair Philosophizing absolutely absolutely um you know and also of course Reichenbach makes it clear that what he's talking about was very revolutionary when it was happening um the idea that's basically been all euclidean how can we imagine that and he tries to take you through it right um that uh time simultaneously could be relative you know and and he doesn't shy Away from the mathematics you know and I was studying mathematics at the
same time his mathemat the mathematics she was talking about was the element I was studying but the terms like grown from calculus they were all they aren't the same as I knew so I thought oh so that is how you get into it you know yeah it was a revelation for me well moving toward the uh topic of our conversation today I wanted to start with some background and so logical Positivism was a hugely influential movement in philosophy and one that still I think incredibly intuitively appealing but it hasn't come up and certainly not in
any detail on the show so far so since much of what we're going to talk about in the development of the philosophy of science is as a reaction in part to logical positivism maybe it would behoove us if I started by asking just what were its General tenants and who its most important figures Well um the tradition was centered on two circles you know there were these philosophy circles in Europe um before the before the second world war um there were a number of them but the two main ones in this tradition were the Vienna
Circle and the Berlin Circle and the other Circle had you know caught now famously um and the Berlin Circle had Reichenbach Famously um and they developed an approach to science that was in itself very successful but afterwards of course we had to see limitations and the main the main influence on philosophy Science teaching was from The Coin App Slide the piano Circle side uh which was Pretty formal right and the approach to science was first of all for all of them that you approach the big theories there were huge theories huge political developments in the
first half of the 20th century studying but at the end of 19th century uh Darwin's theory of evolution um Einstein's uh theory of relativity Now quantum mechanics the next big revolution right and so the focus was on these big theories right and then the other part and the other part of it and this was peculiar to coin up and piano is the theories were to be conceived of in the way that theories were considered off in logic and Mathematics in the foundations of mathematics so Um and that means that the theory is a set of
sentences it has axioms it has theorems right and then the difference from math was that well the vocabulary had to be linked to things that we could touch for this league right um now I think that you know there was a lot of traditional philosophy behind this Um you know in the 17th century um you know the word was you develop your philosophical Theory more a geometrical in other words more or less in the form of mucus hopeless geometry you know and um and so that is what like uh um Descartes and well they got
especially short how to do is also in science right um well you know that There was something very right about it and there was a lot that was learned from this um you know the um a lot of insight in the in in the theorial relativity especially I think right both it was also the more logical and more formally got the more it was out of touch it was actually happening in science Even in the science that they targeted okay I have a few thoughts one just a personal anecdote I don't know if you if
you you might you probably know the name heimgaffman but Heim is a logician and yeah yeah at Columbia and he he's my I'd say father or grandfather philosophy figure and he just has the most amazing CV of all time so he was he was studying with Abraham Robinson in Israel then he went to UCLA to be carnap's research assistant and then tarsky poached him to Berkeley but I always whenever I hear carnap I just think about that because I'm thinks Heim thinks that karnap is one the greatest philosopher of the 20th century but also I
was always talking about what a a wonderful guy he was so that's just what I think about when I hear but it is very interesting the way that I mean the semantic approach what we're going to talk about uh was a reaction to Logical positivism because of what you said about logical positivism becoming very distant from the way that science was actually practiced but it is also interesting that it it is a continuation in a way of this 2000 year old mathematical tradition that comes from Euclid yeah absolutely yeah I would say about the figures
that you mentioned that you know starski is already a bit Of a step away because you know he introduces models and a model is something very close to what scientists talk about all the time you know they present and they present their theories in reality they don't give actions and so on they give you some equations to describe physical systems and then they have to develop these solutions to those equations now solution to the equation that's the simplest form of a model I mean the first the idea that Tasky starts with for modeling is you
can talk about equations or is it better to talk about a set of solutions of those equations it's a kind of shift of Focus right and so uh tasking started right now he introduced that in the 30s it didn't have an immediate influence on site on philosophers hmm well one last thing I wanted to make sure that we touched on a bit because it was so significant to logical positivism Is the distinct the distinction between on the one hand and on the other the the significance of theoretical and observational terms in a language yes yeah
yeah that you know that that became uh the center of controversy right um the uh it's in scientific practice there certainly always a difference being the quantities that you can measure directly And the ones that are so involved in the theory that you need Theory involved in your measurement procedure right um but kind of and his fellows thought that why can't we make a sharp distinction in the language in which we formalize the theory so that what corresponds to direct immeasurable qualities so what they call observation Etiquettes predicates that you can apply directly by observation
and the other predicates theoretical predicates you cannot apply them directly right when you look at something you can you can by looking at something say it's a magnet you have to put doses of iron filings which is your measurement procedure right okay now that okay now I think we come to a basic theme of the reaction against this okay This is that the scientist is not developing his theory in a symbol system he's developing his theory in natural language the natural language you know and um it's not the case that the language in which the
theory is frame so he uses mathematics and you'll see equations you know it's sort of but the terms of those equations refer to quantities that you can talk about in the way we talk about any quality right so The idea behind The Chronic approach is that really you should begin by thinking of the theory as a symbol system and then it has to be translated in some way and there's no perfect way to translate it but it has to be something like a translation so the idea is that the theoretical predicates are in the first
place you know Unintelligible they have to be given somehow right and that is uh you know that breaks totally with what is happening when you're looking at what the scientists are knowing um I mean there's many many ways to point out how it is a disparity between the two right um scientists will say here are the Principles of the theory but when you look at those principles they don't look like the accents from which he's going to make idiot's theorems the pistols are going to be something like the quality is going to be represented by
a vector or a quantity will be represented by um health information operator something like that you see in other words he Telling you how he's going to set up his model right um so um the inordinary language still in natural language that's insane national language that is no sharp Extinction between observational terms and theoretical terms um in terms of our news even to report Observations are Theory Lane um you can carefully distinguish between the different measurement procedures involved so you can do that you can distinguish between the objects that can be perceived and cannot be
perceived but in the vocabulary you know there's no hygienic observation language hygienic meaning having nothing to do With the theory and having never been infected by the theory you know it just doesn't exist so that was a big part of the reaction after the second World War right you mentioned as soon as I asked the question that this was a big source of controversy that on the one hand that scientists do not distinguish between the observational and theoretical vocabulary they're not working in a symbolic system they're working in Natural language but before we get to
the reaction to this received view I'm wondering if there are any other broader criticisms that were levied at logical positivism that contributed to the subsequent reaction against it I mean before the Alternatives were introduced yes yes um it's okay if that's the if that's the the main thing right that is the main Thing I think that you know um in our correspondence we discussed a bit how they were really in what I wanted to talk about free or evolutionary changes right um now I think the third one would be the semantic approach right but the
first one would be let's turn toward realism towards scientific realism uh that's how especially at the Minnesota Center starting in the 50s right the second was The turn toward History of Science that we associate especially with right and then the third one is this turning from theories to models it's a semantic approach and you know I think that all three of them um could be just build as this is the react this is the reaction this is the reaction to the logical positives of course it was happening while That Heritage dominated teaching philosophy of Science
teaching and fossil science textbooks it took a while for any of it to really you know make its impact felt beyond the classroom so yeah so maybe we should before we get into the semantic approach which is the main topic of our discussion I think we should at least briefly touch on these other two revolutions that you just pointed to and maybe we can start with Scientific realism so for my listeners who aren't familiar with scientific realism though I think that it might have come up uh many many months ago in an interview with David
Papineau what what is that view and in what sense did it emerge to dispute ontology yeah well I think that when it was being developed um thinking about the Minnesota center with Sellers and final and Maxwell right it Looked like it was a simple State forward single view but since then um the people even the people who say they are scientific realists and that is most of the people who write in those terms um they're not all agreed about what it is right um I would think that a minimal part of the position is that
Um the business of science is to give us literally true theories about what there is in the world right and that everything that it talks about is supposed to be things that are real um now this is about what what the game is all about what the game of science is all about what is the aim right okay but apparently not just a parenting I Know from many writings that many people who call themselves scientific list add to this a belief nothing current the core of the current accepted scientific theory is is true okay now
I mean of course this is the station there I mean you couldn't believe it this was the aim without believing anything about how well achieved it was so far right well or you could believe that it was you know Achieved in part or approximately whatever and they tend to qualify as a bit um but so but if you go back to the Core then the goal test is between viewers that say no that's not the aim of science and there are different possibilities there um one that has never worked out well it's A purely instrumentalism
saying it is just a tool together all in the world you know well another one um the one that I've proposed there contracted comparison says the aim is just to be adequate about on the empirical level it doesn't really matter about the theoretical entities you know as long as it's successful About um our predictions about measurements manipulation you know um that is the AIM uh and if it is if this aim is achieved using theories and go far beyond the observable part uh and that those extra things are not really there doesn't matter if it
works it works okay so the scientific realist is doesn't accept that no but you know the aim is to give it a relatively true theory In which you only talk about things that are real um just to get some more detail on a couple of issues you said that most and I'm I agree with you on this that most scientists that you've spoken with think that the core of our scientific theories are true and I'm asking if that is in the sense that say the electron has proven such a successful theoretical entity that it's unlikely
to be done Away with in any success or Theory well you know scientists don't tend to make the distinction that you just made um they would all agree that you know as some level of analysis the electron will never disappear from the theory okay even though at some point you don't have particles anymore you only have Fields nevertheless you can still say yeah but you know I use the word Electro and we know roughly what you're referring to right but it will never disappear from The science as it develops but the philosopher of course will
say okay and what about the question but it is real whether it's theory is true or is it just about what you predict about this successful developments in science it's not the same well but scientists will not make that distinction because that's not part about that large world you know they Um I I was talking to a scientist once or a working scientist we worked in um uh in fluid dynamics um but it was very interested to hear about these different debates in philosophy especially about quantum mechanics and I and so he said I've heard
about Both alternative quantum mechanics uh tell me something about it so I started explaining to him and then he said oh um so how can we design an experiment to see which one is right and I said no no no it's designed to give you exactly the same predictions as the ordinary Theory oh he said well then they can just go and play with it in our backyard and he was the woman interested okay so for him the question which is true it doesn't really matter Right and I think that is probably typical and probably
and I think even it should be typical of a working scientist s and then one other question about the scientific realist perspective so you said that and again I'm generally I'm I totally am in agreement with you that this is what how people think of science that it's business is to give us literally true theories about what's in the world and everything it refers to Should be real but how does the scientific realist respond to the criticism that the vast majority of every once thought to be a successful scientific theory has been displaced so how
should their Credence be affected by this in the current in the their Credence in the reality of the theoretical entities postulated by our currently best accepted or best tested theories I think I think that the important thing is not the um the Existence question here it's all about you know they don't have to be disheartened about what you said about you know successful theories having died one after the other right because when theories are replaced by a successor the successor isn't even a candidate unless it can recapture the successes of the previous one okay so
um Newtonian mechanics was totally Successful uh about phenomena where the speeds are pretty small compared to the speed of light in order for relativity Theory to be even a candidate to replace it it has to be able to make essentially the same predictions for that at that level so the successes don't disappear because to be to be a candidate for us being a successor Theory you have to recapture you know your successes Right so in that so that's why I think that no scientist doesn't have to be worried about this because they don't look if
you say what happened to The Ether you say it doesn't matter because what was you know successful about the electromagnetic theory in the 19th century we still have those successes and we will always have them you see Because they were always built into the next one so the question of existence was disappears well granted that the existence question isn't the one that you find most important you alluded to your own view earlier that you didn't refer to it as a scientific assign I don't know if you want to call it scientifically anti-realist or a scientific
Anti-realist position but it's one of the things that you're very well known for and just to keep it simple perhaps with the existence question how do you think of electrons ah um in the way that I think about all theories which is that the scientists constructs models okay and um these models are meant to fit the Phenomena including new phenomena that are specially manufactured in the laboratory in order to test the theory right but now look in the case of the phenomena there are the results from the right measurements that has to be accounted for
but the experience but the experiments are set up um with the design that is dictated by The theory so in order to measure a theoretical quality what you do is two things you have great measurements and you've got calculations by your own Theory okay so that's a very indirect link between the model and the phenomenon because you have to go by you know Theory to measure Theory a theoretical quality um so the general picture is the same for every Theory the scientists Constructs models and properly understood the phenomena have to fit those models in order
for their Theory to be successful and now I think about electrons I would think about Floyd's ego and end okay I don't think history is equally successful right but um what matters is that the model equal starts with this really a mathematical Structure okay it's very abstract structure that he makes that abstract structure has to fit the phenomena or put the government on the phenomena have to fit inside that structure that's what success amounts to well turning then to this second revolution which was Coons the structure of scientific revolutions I mean it really transcends the
the philosophical universe so to speak since so many People will be familiar with it but prior to his work how did philosophers of science treat the history of the subject and my guess is that since we were talking about how the logical positivists construed science in such a different way from actual scientists we might think of them as out of touch with scientific practice and consequently The History of Science well you know that's we have to be careful not to simplify what they were doing you see They were largely in a controversy with the neocantheans
the neocanteans were if the neocandian classical science is an achievement of its own okay I mean I I respect it very much and I think that um going up and writing about respected it too but say what what that is what a neocantian philosopher of science is like yeah the neocantian you see What you might call a plebeian where it really can't is that he's talking about the workings of the Mind right and he's talking about the categories and the space and time as sense as you know um they were sent as our sensibility and
so on um the neoconsian said no if you really look at into what the structure of Camp is describing you're Talking about the prime achievement of Consciousness which is science and so they try to uh they they talked about the Sciences having the kind of structure that Kent was displaying okay um now I mean there are people today who thinks it's very seriously like like Michael Friedman in Stanford right um he is quite willing to talk in those Terms oh Brickman as well okay now but at the time the neocantines that they were arguing with
they were a little other words against they were demurring about relativity um they wanted to insist that [Music] um These apparent revolutionary changes in the world view that were brought by ltivity were really um illusory there were they were they you could be Governor they could be gotten around so as to say that the um traditional standard view of space and time were still right so right my specialty but also going up argued with these people right and part of the reaction to them was to throw Away from this initial way of talking about science
and making things much more abstract there was a lot of opposition philosophical opposition both through relativity Theory and later on the quantum theory um it attempts to maintain earlier conceptions of the world basically like early conceptional space and time emotion and substance and um The reaction both from chronic and Reichenbach was to leave a lot of tradition behind in in his early books Reichenbach talks almost like a neoconians he's slowly emerging from a neocantine background right um it's not not surprising to me that they would have made their view of their approach to science more
and more abstract more and more logic oriented in Order to get away from those disputes and that makes sense but then where does [ __ ] fit in what was so novel about his approach and how was it in part a reaction to what was going on with the logical positivists at first at first it didn't look very novel um you know he published first of all in the escapedia of unified science which was being run by The Logical pause the best and then and you know their Well and kind of liked kun's work very
much when it was published there and I thought it was totally in a you know there was no opposition at all between the way he approached songs and maybe that was the process to put science um now he underestimated the basic differences because once you read cool you really can't Anymore see any division between theoretical and racial language you don't see this guy you know don't see that anymore um you um you don't see the theories anymore as sets of sentences that are actually symmetized and you know that you you don't think over things and
that is how you have to think of the theory in order to really approach the theory and To understand it um and you also begin to realize that the lack of attention to history in that literature the focus on [Music] logical problems with just toy examples was not right you know it it took the philosopher too far away from the subject that he was supposedly studying um So I think that the impact was slowly you know was felt slowly you know it did not hit all that's it didn't have the right it didn't have the
complete impact right away no not at all um but once you start thinking about science the way you do when you're reading the structure of scientific revolutions you don't have any taste anymore for the Logical exercises about you know um white Ravens and Black Swan you know that were in all the textbooks and that people spend the time on and Guru and clean you know I mean no we don't have any more patience for it hmm so the distinction between theoretical and observational terms in a language disappears after reading [ __ ] because his approach
was so centered on scientific practice yes yeah Yes and um you know who himself they throw in became much more interested in issues about language but the reason I think that his book has its impact was that he he was at that point not interested in issues about language too many problems have been generated just by this focus on language um not just in philosophy of science all over the place right yeah The so now enter the semantic approach which you wrote and I'm just gonna I think quote you that the semantic approach replaced the
methodological framework for philosophers of Science and this starts with Frederick soupy who was a Titan of philosophy of science and I think it was in his dissertation that he developed the semantic approach if I'm recalling correct though as you also wrote there were main questions after this time but what were the key Components of this early formulation of the semantic approach that approached The Logical positivist approach that maybe we'll just refer to as the received view now yeah um well you know I have to look back in my own memory and you know I didn't
know prestication I mean um and in fact it was not published outside it possessed his dissertation right Um so he and I both started thinking in the same way because we both had gone back people enjoyment for Neumann and then burkhoff and and in my case also having Weil and and bad um his teacher Arthur Burks was a Wonder Woman fan and so oh Fred soupy had read a lot of fun ointment and had gotten the same message as I did that this is how you should talk about scientific theories yeah Um so in one
way the semantic approach had been developed by these scientists and philosopher scientists well before us but philosophers had not noticed except for one and that was this nationalization and philosopher even Bett um he he wrote a small uh textbook during the war Um and it couldn't be published yet there was no paper there was no paper so right after the war there was paper and it was going to publish it and he was rereading it and he realized Suddenly by thinking about Wonder Woman right and this isn't right this positivistic way of talking about what
implies what in the scientific theory is not right and um So he was the first philosopher to take the lessons to Heart from these scientists um now this of course these were synonymical scientists you know and and advanced work and foundations of physics really um besides for Neumann there was a Hammond Weil and Hammond Weil actually did the best thing but um it was totally unnoticed Um I think it was around 1940 that he wrote an essay in a facet for jusro called The Ghost of modality and um he talks about intuitionistic logic motor logic
Quantum logic and he shows how they all have a certain format that you know you could actually apply thinking about scientific theories um in a logical way um I I found the essay because I was interested in bushro in a book in the library basically right Nobody in philosophy paid any attention to this because the people who invest in neutral were not interested in philosophy or physics right so okay okay so I've been backtracking now from in 1950 whatever report seven nine I forget you know late February late 50s fancy writes his dissertation and didn't
publish it yet um but he and I were talking And we realized that when I was coming through through bed he had come to already two of annoying and then he organized this uh conference in Illinois in Urbana and you know he's he said famously this is the night that they received you died okay well tonight it's night in you know uh when his conference opened by well that's overstating at the bits obviously but in in that conference both spoke and hampel used the term the Standard view of summons and Putnam used the term the
received two of science now you can see hempo was totally in it you know he was totally in his Heritage from the Lord supervisor this and he called it standard because he's not always standard right then button because it receives is because he was already beginning to criticize it you know Um so it's it's true that that's when it began right and then it took off really quickly uh partly because both friends and I have students no and um both of us were giving talks and conferences about it um and the uh the message was
you know the basic message was turn away from Theory as such Turn to the models when you're talking about scientific theory you start talking about a set of models of that theory you mentioned Urbana Champaign and I've I found this so funny when I was reading the the received view guide according to subi on the opening night of this convention and it was the I think called the Illinois Symposium on the structure of scientific revolutions but was so what was so funny To me about this was that there were 1200 people present at this philosophy
of science conference in the middle of nowhere in Illinois and you just would never have that today I mean the the philosophical the academic world has just changed so much uh so I just I got a chuckle out of reading that but returning to one of the central tenants I guess harking back to when our conversation began you said that the positivists thought of a scientific Theory in this euclidean mathematical sense where it was a set of sentences just how did Super conceive of a scientific theory what sort of thing is it and I think
that this is a central question that should help us distinguish between the received View and then the semantic approach well I mean I can I can just give you in simple terms you know this us systematic approach right um this is so the models of the theory are mathematical Structures they are put in the simplest way they're the solutions to the equations that the scientist presents us with Theory the equations I believe Delta Ray is are the description of the models okay um a solution of those equations is one specific model right um and This
but secondly you could say that you know you could say that about equations that don't have any connection with the world right second part is that the theory is about something unlike a mathematical Theory it's about something right um and it is about something because remodels are Candidates for the representation of phenomena in a certain domain and that's that has to be specified so you know I think in the in the in my paper I give example of a diffusion equation and um if suppose you say this is my theory right well the thing is
that you could be talking about [Music] um temperature You know how a diffusion as a heat process or you could talk me talking about the diffusion as gas you know expanding gases right um whether you're talking about heat or about gases those are two different things and so in order to ask you what is your theory I have to ask you first of all what's your equation and secondly what is it meant to represent And then when you say what it's meant to represent then I have to ask you well what are the measurement procedures
see and all of that is part of theory the theory itself specifies the measurement procedures okay some of them are direct measurements you know you could do without having been educated and some you couldn't you couldn't design without knowing the theory Um so something you know um when Ronald Geary was one of the people working in that approach a bit later uh he tried to simplify it and he said it he said the theory is the seven models plus hypotheses about what things in the world fit the models Well it's been oversimplified to put it
that way because you're not talking about you know um what the fitting amounts to then you have to in order to make it precise but as a as a quick you know a 25 word or less um it's a set of models plus the hypotheses about what things in the world um you know fit into those models And returning to something you said at the beginning of your response because the theory is about something in a way that the mathematical theory of the positivists isn't the semantic approach has us take the language that the theory
is couched in more literally than than the positivist does and then this in turn this can be seen as the reaction to the positivists not treating the philosophy of science the way that scientists do yeah yes yeah Yeah so you know um in philosophical practice right I mean how do people in the semantic approach do philosophy science and how is it different from the way that it's going to happen when there's friends with classical science um yes there is a language remains a central part okay but not the same way Oh in The Logical positive
restoration the language that you want to talk about was the language in which the fear as a whole to be formulated it makes the theory could be axiomatized and you know there were attempts to to give examples of this not very successful right because when scientists even at the formational level present theories they're not good in that form right okay Um in the semantic approach you say yeah language is important but it's a very small language that is important it's just the language interested equations are expressed so the basic sentences are all all have the
same form we all have the form quantity Q has value X or equality Q has value in interval y something like that right just that equality as well that's It every single sentence have the same form right now um when you then ask for the interpretation of their sentences um quantity Q is linked to a mathematical entity in the model says oh Q stands for yeah like that permission operator of that factor okay um that Vector function Um and in that model right there are cases where it has this value right um so these sentences
that interpretation is quite telling telling you what this what they describe in the model right and then there are connections between them Um Let me give a very simple example suppose that your model is just you're talking about going to just talk about things having a color red or blue or white okay so then your model will be the basic space in your model would be become respected and the quantity would be color right and then say quality color has value X means something like um you know it's red when it's blue or it's white
and then the value is just One of these wavelengths or whatever you want to have there right well then one sentence will be this quality the color of the object is red another one will be the quality of your this quality the color of this object is blue and you can see that they are logic being compatible right so neurological relations between this because of the interpretation in The model and um then you can Define things like and an or and so on but they just have to do with the content of the sense it's
not syntactic structure so that is important there is a language but it's a very small language it's not the language you must appear as a whole is being expressed it's just the language you have to need to give you the equations and talk about The models that's all so sometimes we were very um sometimes we were arrogant sometimes we were very dismissive about The Logical positivist approach saying they were so language oriented but of course we couldn't mean that language has to disappear no of course not it's just you have to give it the right
place well I'd like to take a little bit of a A detour though not leaving the semantic approach but as you know there I've done a number of episodes recently on quantum mechanics and the interpretations of quantum theory but what is the relationship of the semantic approach to what you call the the quantum mechanics interpretation Wars so how did the semantic approach look at things differently from the received view because quantum mechanics as you already mentioned or quantum theory is One of these three big theories that I think you referenced Evolution and relativity that came
before or around the time of the logical positivists and has been the focus for much of the past hundred years well you know um I was talking about the prehistory of the semantic approach saying what noise well the the first paper to mention the Prehistory is an article by Neumann and berkoff about logic of quality mechanics and now when we look at it we say that is the semantic approach to Quantum Theory okay um so in other words it was in 1936 that the first item was really published so nobody recognized it as such right
now this comes from Norman who had a very specific interpretation of antipolar theory he formed he didn't formalize it but he Uh not in the sense of denotation he didn't formalizing sense of radiation but he presented the mathematical Theory systematically okay um and um so you know the semantic approach was in there from the beginning yeah because the way we want to talk about theaters in general is exactly the way in which The mechanics right so it was immediate that this was a playing field it was the place where we would you know take up
arms so to speak um and so in the you know in the interpretations um after the second world war right um we could see this actually going on in many places but mostly by scientists so Um in Switzerland there were elf and pieron developing what they call the logical approach to quantum mechanics in Italy toraldo and melakiara [Music] um in Germany middle steps in uh Finland and so on and so forth they were all doing this they were all mathematical physicists basically working on donations right and philosopher stepped in Um we all went on a
Dubai all went added in this logical way which was basically the semantic approach um Jeffrey Boop who had been a student of bone then you know develop what you call The Logical interpretation The Logical and the based on quantum mechanics um and later on showed how there was a Whole array of things included in that form so that's the connection between the two that a lot of the work was suddenly being done in particular in that specific form is something particular that I want to ask about you already mentioned by Neumann and Bohr but how
did Bohr conceive of the division between micro and macroscopic in nature and then how Did Von Neumann respond to this yeah you know there were two big issues okay um and there was a sociological change between before the second world war and after the second World War right um born the Copenhagen scientist like Heisenberg were very influential right And many scientists I think simply follow them uh for Neumann to begin didn't think that he was doing anything that they were not doing that he was just actually explaining what they meant um there the Copenhagen view
was this yes equal the mechanics the physicist is building models of the phenomena but he only builds a model of what's on the other side Beyond his instrument There's always this dividing line that he only makes a model of what is the only instrument now if he wants to model the instrument too fine but then he steps one step back and defining lines of the folks and that's all okay um so that means that you cannot have her you can never think that the world is a quantum mechanical system because there's no dividing line anymore
If you say that right so this was the point their point of view their um you know Observer it's always Observer relative or observation relative or a measurement relative right um the big opposition to that was not you know for Norman was totally in in according to that he tried to explain it He tried to make it clear that you could consistently say this right um when it was not accept it was in Russia in Russia they thought that the Copenhagen people were idealists and um you couldn't be a more exist and be an idealist
you have to be a realist okay so they and they you know they their physicists wrote about a very interesting ways to walk in chat for example It's just mechanics it's just mechanics just like Tony mechanics okay um that point of view you know was not there in the West uh until after the second world war and then suddenly you see it dropping up all over the place um we had rival interpretations of quality mechanics and a big shift because they wanted to use quality mechanics in Cosmology now cosmology has a theory about the world
as a whole so if you want to use quality mechanics there you have to say the world is a quantum mechanical system and so then you can't say it's observed relative because there's no Observer outside the world and um so these new interpretations that many world's interpretation bombing Rome's Interpretation you know on these they all start with you know it's not observed relative we're talking about is this everything is a mechanical system it's called the mechanical system um but then you know there was no single way to do that there were many different ways to
do that no all of them having the difficulties obviously they would all be developed I mean you know lots of Problems to solve right but it's very interesting to see this big change you know that happened in you know this that suddenly it is this way of approaching the theory so that it could be a theory that would you know not have this Observer relative limitation we came Sunday the gospel right now that wasn't broken until River Valley in the 90s okay so I can I'll talk about that Because that's after the period we were
talking about but but um it's the main dominant among the interpretations um nevertheless looking at it you know from a logical point of view uh it was possible if you wanted to maintain some of the insides of the Copenhagen School against um sure sure but you know I'll before you talk about that I'll just mention one Thing because I pulled up a quote from you that I thought was really nice and you said that Von Von Neumann had already given the correct response in the 1930s to bore and it is there is no dividing line
in nature but only one drawn by the modeler who chooses what to model and I thought that was really good correct exactly right yeah and but for Norman I think didn't think he was disagreeing he thought he was explaining yeah yeah okay but no please continue Okay well so after the war uh everybody working on it took the point of view yeah not observe a relative okay I thought it was a relative it's just about physical systems in the same forward you know mechanics right okay but then the question was could you still maintain some
of the Copenhagen views um where there still wants it you know um you could and What that meant was uh does every interpretation have to have hidden variables um or could you hidden variables meaning things really made a physical difference but then we're not coming out in the experiments that were being done right whereas the government however if you would have said no if it doesn't come out in the experiments there are there's nothing there Right and the answer is yeah yes you you could you know and I'll tell you what is a very very
basic point or where season rotation is differ um that are more Copenhagen and less common um suppose you have two qualities q and R let's say right and the theory tells you they can have certain values And when you do make your measurements unfortunately there's no certainty about its value you'll find and this was typical in quantum mechanics that would be on indeterminism in your measurements results um you make the same measurement twice you'll get you may get two different answers okay um but The theory will tell you there's a certain statistical distribution in your
answers for instance you know you have some uranium here and a geiger counter there's a nice statistical pattern in in the number of clicks over a long run over the long run so we call these the measurement statistics for that quality now here's the question suppose two qualities the same measurement Statistics are they the same quantity are they just two different you just have two different natures and money or could there be different qualities because in fact there's a reference to something that's not coming out in the message in the specimension statistics okay well sometimes
people use the word realism there and they say second alternative or realist but I mean that's you know A confusing adaptation of the word realist really right I mean both are very safe forward ways of talking about physical systems so the the Copenhagen line would be nope that is you know nothing there that doesn't come out in the measurement three thoughts and the anti-government harm too you want people who put in Hidden variables they say sorry you could have two qualities Same measurement statistics but they are matching something different and so well the actual metal
procedure is might depend on the context and which is done for example um you can see how the Copenhagen line is a very empiricist mind right they are not willing to give uh They don't respect things that don't come out on a horrible level where you see the measurement results whereas the um things like um bromian interpretation right um they have a different point of view about this yeah foreign well I think unless you wanted to talk about rovelli which I'm I'm fine with With I'm fine with doing I thought that uh maybe it would
be a good time to turn to perhaps briefly some criticisms of the semantic method okay that well one and I'm sure that there are some that I'm not aware of that you might tell me but one that a prima fascia criticism that just occurred to me as I read is that a while I think presenting a theory means specifying some models or some structures one of the important ideas Though of the semantic approach is to return to how scientists think of and employ scientific theories but I don't think of scientists as thinking of scientific theories
as abstract mathematical structures so this just seemed somewhat incongruous to me yeah well yeah that's I think that um the more the more you're logically inclined the more you will think that way but um it's not obvious to begin I agree so for instance You know the first thing when people say model they they should think about model airplanes um or other little physical models that we have or big ones so here in the Bay Area now this is huge model of of the San Francisco Bay um up up in Marine County and you can
go and visit it and they built it in order to study water flow in the bay okay and what would be the effect of silting for example But you know what when they use that model what do they use they use the numbers that come out of the measurements under the measurements they're making on this on this in this model and as a matter of fact for the last 20 years you can go and visit it still and still there working but beside this and I was just using a computer model okay For the same
purpose because it I mean I would say it is What mattered what was important about this big structure that they made in Marine County was not any of the physical details it was a structure in the abstract sense of structure and the fact it's the mathematical structure of the physical model that is the real model that is the model that The scientists use right um so I think that um when they talk about physical models when they're real or imagined right nevertheless what they infer from what they do with the model right could be duplicated
you know in a computer model which is a mathematical object right now Again you know what you see in your computer screen doesn't it doesn't look mathematical it look you know you see lines Instagram but actually what it is of course it dictates an automatic structure right yeah so really and bottom it's all mathematics yeah when I when I hear when I hear model I think domain relations interpretation function and I definitely I don't think model airplane so I think that that clears up the the confusion there yeah well you know you're thinking it would
be as a debate it's studied in logic right um and you know the models right but you know you know different positions will be more or less that way so Abraham Robinson you mentioned right um he talks about families and models as families of Mathematical structures and the interpretations were comes along the way you see what I mean whereas that you're watching textbook everything is about the interpretation functions so you know it's ways of thinking about the same thing well maybe then it's a good time to turn to epistemology in the philosophy of science and
I think we should again start by Discussing what was replaced and the first thing that comes to mind is the hypothetical deductive method or model of scientific inquiry because I learned that in high school and I remember thinking it was the end-all be-all of what science ought to be maybe you could just say what this method was and how it relates to the the formal view where theories were treated as sets of sentences in the mathematical tradition So you know um is a basic idea which is certainly like that if you have a theory right
and the theory implies that something will happen on these in circumstances then you go and check and see if it happens in the no circumstances and um if it doesn't then you say something wrong with the theory and if it does then you say well then Bears out the theory okay so far so good right um now When they develop this idea in The Logical positive explanation the theory the set of sentences the implications were things you could deduce from the theory plus you're given about the circumstances right and then they said if if it
actually happens that confirms the theory okay now the fact is that once you put in that form they're very quickly trivialize it because if If it's true that just a verified implication is a confirmation right they say look suppose that theory T implies a and a is true right well Theory t plus X also implies a in that case so it verifies t plus X as well right um that's funny you know because t plus X could be t plus anything you like right there's something this looks like a sort of sort of trivial there
right And um um it's just it's a really oversimplified thing um the other thing is of course they tried to say then how much does it verify how much does it confirm and um you know it can't be quality I mean you know the sun rises every day but you think it gets you know the number of sunrises you know makes all the difference about how this theory is Confirmed usually they do one experiment then to say hey it worked out right something else is going on something else is going on um so that was
a very oversimplified idea um and you got these uh these puzzles about you know um the Ravens I don't think they should start going back to those things okay so it all just You know came to be thought of as this is so naive that you know we don't work but we don't do that idea anymore it's it's you know the basic idea is still there but that's it so what are we going to have instead now he is a real case in science and Darwin realized that you know he didn't have hypothetical deductive Confirmation
for his theory okay um nevertheless he said look look at everything that I found isn't that support for the theory no and he pointed out that for electromagnetism too you couldn't just go away you know confirmware confirming by observable events it was a lot more to the theory that didn't come out that way so what happens is that and um I think that's something One of the first really nice things that happened and I was when I wasn't you know just katsubi and me and Ron Berry you know um saying semantic approach was when my
student Elizabeth Lloyd said let's do this in philosophy biology and she took up governance Theory and she analyzed what kind of evidence support he had um very specific cases analyze it as he was building a model and the model included some assumptions About you know how the model would work and where whereas the model is it's itself is not like a hypothesis you can test you can go and see if those assumptions actually it can be checked and if it all works out then you know you have a you have an evidential support of A
Sort that is not recognized in the traditional View Um since then I I've done a two game examples from physics instead um for example you know um the cartesians really objected Newton saying that he's into single cult qualities mass and force the only thing you can measure directly is what the measurement your ruler in your clock okay in other words kinematic quantities Qualities of time and space that's all you can measure directly but now Newton has introduced massive Force they are occult qualities it is you know this is not real science they were saying because
you can't measure them and the Newtonian scientists said yes we can measure and then they developed you know experimental setups in which you could say measure the mass measure the force But how did they do that well the design of the measurement apparatus is dictated by doing the theory now if you think of this as an attempt to confirm then it just a vicious circle it's a circular because then the premises include his theory right and so um but it's not true it's not only a thing Called for because it could turn out wrong they're
not false nevertheless your measurement even if you if you design your measurements using the theory the measurement result may still not fit the theory and so there's still a question is that is the theory going to be borne out by this procedure or not much more complicated than anything you could discuss with like hypothetical reduction sphere method or whatever Called confirmation principles you know it's uh it's about model testing and uh model testing and uh using Theory mediated measurements for your qualities you can talk about this very straightforwardly within the semantic approach you couldn't make
any sense of that as long as you've already received to received you one further question I have then is after all of this by what criteria are we to Judge the value of a scientific theory do these change whether we take the semantic approach or the approach it displaced do they have different criteria for the value of a scientific theory not in practice you know they they receive you and the semantic view are both attempts to get clear on what exactly scientific procedures are right and I think that what those real procedures are that's There
in the world of science that's what's happening and what science scientists do um I do think that with the semantic view we became much clearer we've got to understand it much better right but no there is no nothing that would imply advice to the scientists to change what he does no well most of what we've been talking About so logical positivism aside but the semantic approach that we've been discussing centers around events philosophy in the second half of the 20th century and just toward finishing I'm wondering what candidates you see as promising Replacements to the
semantic approach if any well you know it's hard to say even in the middle of things right Um I think that um plus your science has compartmentalized a lot and the semantic approach was still very logic oriented there are people in classical science who are who are very logically oriented today um and so but I do not see them as uh having this you know huge effect on how Things are gone generally or how are you going to be done in the textbooks right um because it is too it requires too much background for you
know people like if somebody is working philosopher science is working on archeology for example do they need a great deal of logical background no right so why should they study Um you know logic of quality mechanics I mean no no I mean um I don't I I can't help but think that these very logic oriented philosophy of science are going to be important but you know not at the center no not what you will see most of right well quite on The on the opposite side that is the movement that's called science and practice the
science and philosophy of science and practice [Music] um it was very vigorous for a while with lots of conferences and lots of uh papers and then I think maybe you know it did you know Didn't seem necessary to be very purist about it anymore and so um you know it's the um [Music] and influenced what was happening every matter I think in all parts of philosopher science I think there was some impact of the positive science and practice movement um again I don't see that it doesn't take over everything you know Um I think as
you're not our third another thing that I think was an important development that for a while a lot of people were working in that area and that scientific representation you know uh there's a new book coming out by Mariachi as soon as um so the subject is still continuing but again it there was a period of very vigorous very widespread uh work uh that maybe is not quite some figures now Um the thing is that you know there's like I think here's what I would say about philosophy of science itself um many areas of philosophy
the problems are totally self-generated by the philosophers in philosophy of science you know you go and look at something that's real the world maybe the sciences and find the problems they are um and um I would say that something to be said in favor of law school science well boss it has been so cool to talk with a living legend in the philosophy of science so thanks so much for doing this to me and especially for covering some fairly esoteric material yeah I know it's been I know so that's quite esoteric but you know this
is the history of the 20th century and it's and all of it is important I think okay thank you for doing the interview With me I really enjoyed it foreign [Music]
