Frege and the Language of Reason

John Perry
You know Frege is wrestling with something when he writes these long paragraphs.

John Landy
Coming up on Philosophy Talk: Gottlob Frege and the Language of Reason.

John Perry
“Identity gives rise to challenging questions which are not altogether easy to answer. Is it a relation? A relation between objects? Or between names or signs of objects?”

Ray Briggs
How much does language influence which thoughts we can think?

Josh Landy
Logic helps us think clearly, but can it also give us insights into the world?

Ray Briggs
What if there were rules that you could follow and always reason correctly?

Josh Landy
Could there be a way of speaking that taps into deep philosophical insights about the nature of reality?

Ray Briggs
Could there ever be a language that’s free from all ambiguity?

Missing Persons
What are words for when no one listens anymore?

Josh Landy
Our guest is host emeritus John Perry, author of “Frege’s Detour: An Essay on Meaning, Reference, and Truth.”

Ray Briggs
Frege and the Language of Reason

Josh Landy
…coming up on Philosophy Talk.

Josh Landy
What if we created the perfect logical language?

Ray Briggs
Would we gain important new insights about mathematics?

Josh Landy
Could we find deep connections between ideas just by studying the grammar of sentences?

Ray Briggs
Welcome to Philosophy Talk, the program that questions everything

Josh Landy
except your intelligence. I’m Josh Landy.

Ray Briggs
And I’m Ray Briggs. We’re coming to you via the studios of KALW San Francisco Bay Area

Josh Landy
continuing conversations that begin at philosophers corner on the Stanford campus where Ray teaches philosophy, and I direct the Philosophy and Literature Initiative.

Ray Briggs
Today, we’re thinking about Frege and the language of reason.

Josh Landy
Oh, yeah, Gottlob Frege, the German philosopher from the turn of the 20th century. Didn’t he invent a new system of logic or something?

Ray Briggs
Yeah, exactly. He developed rigorous standards for definitions, he came up with a whole new way of thinking about [unintelligible], and he even redefined how we understand mathematical proof.

Josh Landy
Okay, that’s interesting. But why did Frege need to do that? I mean, mathematicians have been proving things for centuries, the Greeks had geometry, the Islamic empire had algebra, the Chinese mathematicians of the Han dynasty had those really sophisticated methods for calculating pi.

Ray Briggs
And all that was great, but their arguments just didn’t look very much like the rigorous proofs we have today. I mean, yeah, they proved a lot of cool things and their calculations mostly worked, but Frege had a comprehensive way of checking whether they worked.

Josh Landy
So no one knew how to check proofs until the 19th century?

Ray Briggs
Well, they did. But Frege was systematic about it. He had rules that you could use to check a proof every step of the way. And if you follow them, you can be absolutely certain that you hadn’t made any mistakes.

Josh Landy
Okay, so Frege had a system for checking proofs, but But okay, riddle me this Ray. How did he check his own system? Or did he use his own rules? I mean, that’d be like, trying to figure out if your thermometer is accurate, by using your thermometer.

Ray Briggs
Okay, yeah, that is a fair point. I mean, in fact, Frege’s system turned out not to have been perfect, and people did find out that one of his axioms leads to contradictions.

Josh Landy
Wait, so this guy revolutionized math by adding contradictions? How’s that supposed to be an improvement?

Ray Briggs
Okay, okay, so the details weren’t perfect, but the central ideas were still good. I mean, having some system of rules is important, even if Frege was wrong about exactly which ones. And he also just gave us a rule to use for making logical arguments.

Josh Landy
But didn’t Aristotle already have a language for making logical arguments? Fido was a dog. All dogs are mammals. Therefore, Fido was a mammal. That’s your good old fashioned syllogism right there?

Ray Briggs
Well, yeah, Aristotle had a system, but Frege’s system was so much better. Like look, lots of arguments are logically valid, but you just can’t express them with syllogisms. Like, here’s one. So somebody has been stealing chocolate chip cookies in the studio. Ray does not like chocolate chip cookie. Theif obviously does like chocolate chip cookies, therefore Ray is not the thief.

Josh Landy
Likely story. Maybe Ray has a friend who likes chocolate chip cookies.

Ray Briggs
A nice try, but it isn’t me, and that’s what Frege helps us understand — that I’m innocent.

Josh Landy
Oh, okay. Okay, humor me Ray. How does Frege help us prove your innocence?

Ray Briggs
We get this really helpful theory of the equal sign. So if Ray equals the thief then anything that’s true about Ray has to be true about the thief too, but since the thief likes cookies and I don’t, then I’m not the thief.

Josh Landy
All right, I believe you. It must be somebody else. And all of this works great for cookie thieves. But, but does it really work as a general principle, Ray? I mean, take Lois Lane and Superman. Right, Lois Lane thinks Superman is really cool. Superman equals Clark Kent. But Lois Lane does not think Clark Kent is really cool. So how would Frege explain that?

Ray Briggs
Okay, yeah, that is a problem, but Frege had stuff to say about it. I’m hoping our guests will be able to explain more. It’s our old friend John Perry, who wrote a book about Frege after he retired from co-hosting this show.

Josh Landy
One thing I want John to explain is how Frege would make sense of real world confusions and never mind Lois Lane and Superman. What about everyday cases of mistaken identity?

Ray Briggs
So glad you asked, Josh. We sent our Roving Philosophical Reporter, Holly J. McDede, to explore how identity confusion plays out in real life. She files this report.

Holly McDede
Before we begin our saga of stolen identity, would you believe the music you’re hearing is by an experimental band named Frege?

Rafael Durand
Part of music—of language itself— is what attracted us that philosopher.

Holly McDede
Rafael Durand plays the keyboard. He says he was reading Frege’s “Sense and Reference.”

Rafael Durand
At the beginning of the band, we were very inspired by that and we started to look for these truths that were just above our subjective, like extra subjective truths within music.

For example, the octave, you know, the first C note, a middle C note, how it relates the next one. It’s not simply a matter of subjectivity. It’s not like arbitrarily you call this one C, and this one C an octave above. It has kind of a scientific relationship like a degree of undisputable truth.

Holly McDede
Now about those stolen identities…

Axton Betz Hamilton
You see depictions of a dangerous person wearing a tan trench coat and in a hat hiding in the bush.

Holly McDede
Axton Betz Hamilton grew up in the 80s when they taught ideas like “stranger danger.”

Axton Betz Hamilton
You know, in my 11 year old mind, that’s what I thought an identity thief looked like.

Holly McDede
Axton is a Professor of Consumer Affairs at South Dakota State University. She grew up in a small rural community in Indiana called Portland.

Axton Betz Hamilton
You know, I grew up surrounded by cornfields, and we had animals and it was like every typical rural Indiana life.

Holly McDede
But then unusual things started happening. Her grandfather passed away when she was 11, and her family’s mail went missing.

Axton Betz Hamilton
Our mail was delivered to a large yellow metal mailbox out by the road and my parents just thought, “Oh, somebody’s driving by and stealing the mail.”

Holly McDede
The personal information in their mail was used to obtain credit cards, bank accounts, and commit utilities fraud, Axton’s mom drafted a list of suspects: family members who seem to be spending more than their means.

Axton Betz Hamilton
It seemed reasonable. And it seemed like there were all these people in our lives that just weren’t behaving in ways that they should. And somehow all these people were just surrounding us.

Holly McDede
Axton’s mom worked in the financial industry and had gone to college, so she and her dad trusted her to have the answers. This was before credit freezes and fraud alerts. So there weren’t a whole lot of solutions. The family just withdrew and stopped going into people’s homes or family gatherings.

Axton Betz Hamilton
The world pretty much became me, mom, and dad.

Holly McDede
By the time Axton was 19, she learned her credit score was in the second lowest percentile in the nation.

Axton Betz Hamilton
It affected my ability to obtain utility services, you know, basic things like electricity and water, phone service, things like that.

Holly McDede
Axton decided to study identity theft in graduate school because she wanted to address the lack of support and understanding she experienced as a victim. She says research shows that parents are the most common perpetrators of identity theft, but that didn’t enter her mind as a possibility until February 2013. It was 13 days after her mom had died from leukemia.

Axton Betz Hamilton
My dad was in an outbuilding on their property, and was going through an old file box in Mom’s, and he calls me, and he’s just livid at me for running a credit card over limit in 2001. I said, “Dad what credit card is it?” He said, well, it’s First USA. I said well, that that’s one of the credit cards that was taken up my name as part of the identity theft. What’s Mom doing with that?

Holly McDede
Her dad explained the statement was there along with Axton’s birth certificate, and that’s when Axton’s blood ran cold. She understood her mom was the person who had stolen their identities. She says the process of grieving her mom’s death stopped there.

Axton Betz Hamilton
The best way I can explain it is, how can you grieve for somebody that you clearly didn’t know? And it’s very clear that there were several dimensions to Mom that I didn’t know and that clearly Dad didn’t know either. I’m not sure anybody really knew who she was.

Holly McDede
Axton later wrote a book about identity theft, titled “The Less People Know About Us.” She says there is an irony here. Her own identity now revolves around studying the crimes her mom committed. For Philosophy Talk, I’m Holly J. McDede.

Josh Landy
Thanks for that fantastic report, Holly, I could easily imagine myself getting into a scrape like that. I’m Josh Landy, with me is my Stanford colleague Ray Briggs. And today we’re thinking about Frege and the language of reason.

Ray Briggs
We’re joined now by John Perry. He’s a Professor Emeritus of Philosophy at Stanford University, not to mention the co-founder and longtime co-host of this program. He is also a prolific author, including a recent book entitled “Frege’s Detour: An Essay on Meaning.” John, welcome back to Philosophy Talk.

John Perry
Well, glad to be here. And you guys are certainly doing a great job.

Josh Landy
Oh, thanks very much, John. It’s so great to have you back on the show. It’s been a few years now since you’ve been a co-host around these parts, so what are you been up to in between times?

John Perry
Well, I’m retired. My kids are grown, my grandkids are grown. There’s a pandemic. So I sit here and go through my emails in the morning, that takes forever. You know, then in the afternoon, I work on books. So I wrote the Frege book, I wrote another book, “Revisiting the Essential Indexical,” or something like that, and now my book on freedom and determinism.

Ray Briggs
So this book about Frege—what made you decide that this guy is really important and important enough to write a whole book about?

John Perry
Well, I wrote a whole dissertation about him 50 years ago. So Frege is an extremely important philosopher and logician, and logic due in great part to the innovation. See, [unintelligible] has become a large part of the intellectual landscape. So it’s very important to computer science and things like that.

Ray Briggs
So what do you think is Frege’s biggest logical innovation?

John Perry
Well, I think his the most important book when it comes to logic was his first book, “The Begriffsschrift” of 1879. He was born in about 1848. And he has some great ideas in that book, but nobody recognizes them as great ideas now, because we all learn them in introductory logic. So “der Begriff” is German for concept. But what did he mean by concept? Well, he didn’t mean an idea like we might. He mean,t as near as I can tell, what we would tend to call a property or relation now.

Ray Briggs
Right, so I guess like the property of liking. So if I assume, then that’s, I guess, that’s a relation. So that’s a concept is liking that is between.

John Perry
So let’s take the whole sentence, “Ray likes soup.” Frege would say, “Okay, okay, now, you guys all learned in fifth grade or seventh grade, that that’s a subject predicate sentence. The subject is Ray. And the predicate is “likes soup.” But that’s wrong. Forget about it. But make the point, “Ray likes soup more than Josh does.” You’re taught Ray is the subject of “likes soup more than Josh does” as a predicate. Forget all about that.

Ray Briggs
Oh, so I was lied to?

John Perry
Yes.

Josh Landy
What about?

John Perry
Yes, subjects and predicates. But he would say what we’ve got here is three things. We’ve got Ray, an object. We’ve got Josh, another object. And we have the concept. The concept is “like soup better than” and think of that concept not as however you were taught in English class. But think about how you would have been taught in math class. In math class, you’re used to functions which have arguments. So plus is a function. Seven is an argument five is in the argument. Seven plus five equals, I have to think about that. Frege wouldn’t have trouble but anyway, so you got a concept, which I treat, Frege treats, as a function, which is familiar to you from math. You got two arguments, and then you have a value. Right? So with seven and five the value is to 12, I don’t know. With this, you got Ray likes soup better than and Josh, what does that yield? Oh, yeah, eventually that’s what you say, true. Or maybe false? I’m not sure.

Josh Landy
You’re listening to Philosophy Talk. Today we’re thinking about the German logician, Gottlob Frege with our old pal John Perry.

Ray Briggs
How do you know when an argument is valid? Could inventing a new language help you think more logically, and what’s up with Superman and Clark Kent anyway?

Josh Landy
It’s a bird. It’s a plane. It’s a puzzle about identity, along with your comments and questions when Philosophy Talk continues.

Wait, so that guy from REM is Superman? But if Clark Kent is Superman, I guess that guy from REM is also Clark Kent. I’m Josh Landy, I think, and this is Philosophy Talk, the program that questions everything

Ray Briggs
except your intelligence. I’m Ray Briggs, and we’re thinking about Gottlob Frege and the language of reason with our old friend John Perry, author of “Frege’s Detour.”

Josh Landy
We’re pre recording this episode and unfortunately, we can’t take your phone calls, but you can always email us at comments@philosophytalk.org, or you can comment on our website where you can also become a subscriber, and gain access to our library of more than 500 episodes.

Ray Briggs
So John, earlier and I, Josh and I were talking about a puzzle, Lois Lane, and like Clark Kent, but Superman and Clark Kent are the same guy. So why was this kind of puzzle such a big problem for Frege?

John Perry
Well, I’ll tell you in a minute, but first, I want to finish up what we’re talking about a second. Sure. So let’s take a simple sentence. Let’s take “Superman is stronger than Clark Kent.” That’s a perfectly good English sentence. Frege would say don’t think about subjects and predicates, think about, say two objects, Clark Kent and Superman. And this word between them is stronger than, Superman is stronger than Clark Kent. Think of that as a function. What is the function?Tthat verb, is stronger than. So it’s a function of two arguments. Well, if it’s a function, it should have a value, yeah, the value is the truth value. Now, in The Begriffschrift, he actually didn’t say the value of that function was a truth. But he said it was a circumstance.

Ray Briggs
Wait, so the value of the sentence can be either truth value or a circumstance. You’re going to tell us what those are and why that matters, right?

John Perry
Well, he changed his mind. In The Begriffschrift, he called it a circumstance, which will just be what we would call a fact if it was true, or just a circumstance if it wasn’t true, sometimes called state of affairs. Later on, he rejected that and said, no, it’s just the truth value. Those kind of two steps in The Begriffschrift, you got a circumstance, if it’s the fact, then the sentence is true. [Unintelligible], it is false. Later on, he changed it. And that’s when I think he went on a detour. So I just want to get that on the record, but it’s not what we want to discuss now.

Josh Landy
Okay, I want to take you back to something you’re saying a moment ago, you were giving the example of Superman being taller than Clark Kent or Clark Kent being taller than the Superman. Frege didn’t write about Superman, but but he did write about these identity puzzles, where you might be referring— two people might be referring to the same person or the same thing, but using different names and get into confusion. So what’s so important about Frege’s thoughts on that topic?

John Perry
Yeah, so in the picture we’ve got now so far with Frege, you have a sentence, it’s got expressions, then the expressions like Superman and Clark Kent stand for individuals, and other expressions, the concept words, they stand for concepts. And so we end up concepts or function. So we’ve got a function with two arguments, and then we got a value. Now, he found some problems with reference, though. Well, he inherited a very old problem. What do you do about a man and some man? They look, they behave just like names, but they aren’t names. And he says, ha, once you start thinking about functions and variables, that all falls into place.

Ray Briggs
So wait, wait, why aren’t the names?

John Perry
Well, what do they mean?

Ray Briggs
Some man, I guess?

John Perry
Some man, yeah, but I mean, if you’re doing logic here, you gotta be precise, so you got okay, I can sense I’ve got Superman. Look at my rulebook. Superman stands for this guy. I look at my rulebook “a man”, there’s nobody named a man. Right? Adam, there’s an Adam, but there’s not a man. Or maybe it’s a kind of a funny man or a combination of all men or a slice of everybody or something. And Frege said, no, you just got to remember that we got functions here. So we got variables. And what a man wears a cape. Superman wears a cape. You know what how that works. A man wears a cape. That means that there’s a relation between wearing a cape and being a man. It’s a higher level relation. There’s at least one thing that has this first property and also has the second property. So a man wears a cape. He invented a little notation means backwards ex, which wasn’t his notation. But anyway, that’s the one we use now. Backward ex, there exists, man X and wears a cape X. That doesn’t. That means that there’s at least one man, there’s at least one individual that is both the man and wears the cape. Now we’re taught this in about two minutes in logic. It took about 2000 years for Frege to come up with a solution so he doesn’t get enough credit.

Josh Landy
Okay, but how does that how does that help us solve puzzles like “Lois Lane thinks Clark Kent is, you know, a bit of a loser. But Lois Lane thinks Superman is really awesome. And yet it turns out the Clark Kent and Superman are actually the same person. ”

John Perry
Yeah, or here’s the example I like. So Lois Lane and I are at a grocery store. And she sees Superman walk by, and then she can’t find him. She looks for him and can’t find him. But I know, unlike Lois Lane, that Clark and Superman are the same. And I see Clark Kent, and I tell her he’s over there and point to him. And she says, no, that’s not him. Anyway, so that was a problem he didn’t solve on The Begriffscchrift. The problem of what I call significant identities, or unknown identities, What’s going on there? Then he had a very strange approach that he later rejected. And everybody thinks this kind of is not very satisfactory. Later on in the next phase of his life after he finished The Begriffscchrift, before he developed his theories in “Sense and Reference” 10-15 years later, it occurred to him that it was a bigger problem than he has thought.

Ray Briggs
Okay, so it seems like The Begriffschrift didn’t solve this problem about Superman and Clark Kent, and Frege tried to solve it later. But you said The Begriffsschrift thing that Frager did are one of the most significant, so what what advances did it make?

John Perry
Well, the main advances was to get rid of the subject predicate thing and to think of concept words, not as mental but as function terms. And there was another old problem, what’s the relation between properties and and relations, words that people have been puzzling about for 2000 years, and Frager saw that by ignoring it, says, well, you got one place functions and two places functions, and third place functions. And these are all built into your basic logic now. But the problem he couldn’t solve really doesn’t so much come up in basic logic. So he thought it just had to do with identity sentences. If you got rid of identity sentences, you wouldn’t have this nagging problem of two names for the same thing. I mean, you would have two names with the same thing. But you wouldn’t, you would, you just wouldn’t have it. But he was wrong, didn’t go away. Later on, he thought, you know, the Babylonians thought the morningstar was one thing, and the Evening Star was the other one. And they call the one Phosphorus and the other Hesperus. And really good astronomers that had been grants from the Babylonian NSF for weather didn’t know for a long time that that Hesperus is Phosphorus. Now, it wasn’t a matter of identity sentences, one of them goes out and says, “Oh, look, I’ve really observed Phosphorus now for several mornings, and I think Phosphorus has no moon. How about Hesperus, does it have any moons? I don’t know that. How would I know that? Consistent that Phosphorus has no moons and Hespherus has seven moons. Well, how can that be if they’re the same planet? But it is, so what’s going on? So he decided no, the problem wasn’t just with the identity sign it was with the phenomenon of identity. And then later, he only begins, “ah the problem here is that we use sentences for two things. We use sentences to describe the world. And we use sentences to describe the content of people’s thoughts.”

Josh Landy
You’re listening to Philosophy Talk. Today, we’re thinking about the German logician, Gottlob Frege, with our friend and former colleague, John Perry. So John, what you were just saying, that sounds like that’s the solution to the Clark Kent/Superman problem, right? Because it’s not using words not just to refer to things out there in the world, but you’re also using words to refer to the content of people’s thoughts. For example, this person Lois Lane thinks that Clark Kent isn’t Superman. Am I getting it right about Frege’s solution?

John Perry
Yeah, so we use sentences to describe people’s thoughts by betting them but in a that clause, and then we say, Lois believes that Clark Kent doesn’t wear a cape. Lois believes that Superman wears a cape. But Superman is Clark Kent, is there a problem there? No. If we were talking about Superman and Clark Kent, the sentence couldn’t both be true. But we’re talking about Lois’s mind. We’re embedding them in a belief operator, we would call it now. And so they can both be true. Language has these two functions, describing the contents of minds and things, and describing the world. And guess what, Frager says, for logic, we just need them to describe the world. We need to get it straight about how you get a consistent description of the world, and inferences and so forth and so on. And we can leave the whole business of what Russell called propositional attitudes to the philosophers. Frege didn’t quite put it that way. He wrote an essay about it that philosophers have liked ever since. That’s another one of his big influences, but for him as a way of getting rid of a problem, and it got in the way of what he wanted to do with logic.

Ray Briggs
We’ve got an email from Jorge in Atlanta, who asks, “How did Frege influence the Vienna circle? And how was the propositional calculus that he invented different from Aristotle’s logic?”

John Perry
Well, let’s start with a second question. Logic up until Frege and of course, I’m greatly oversimplifying and forgetting about people like [unintelligible] that make great contributions but basically if you go back to Aristotle, its patterns, you know, the logician gives you valid patterns like the syllogisms. If everyone who wears a cake was from Krypton, and Superman wears a cape, then he’s from Krypton, so forth and so on. Those are valid patterns of reasoning, and a lot of those were identified over the years. And so there’s a substantial amount of logic known. But we didn’t have until Frege, a single theory with some axiom, from which the whole thing could be figured out. And he had his own notation, which I think is quite beautiful. But that didn’t catch on. But the Rousseau was the main notation that caught on, and logic became a respectable enterprise, you know, proven known results that you could use fancy typography to express and charge money for books about and require all the pressure taken. Well, what we call real science. But the topics that it didn’t directly deal with ,these issues about the content of things, turned out to be very important for philosophy beyond logic. And it turns out that what Frege said about them in his essay on sense and reference, became very influential. And what he said basically, was, you got this language with no embedded sentences. And that’s what we need to describe the world and reason about the world. And then we’ve got these embedded sentences. And what the embedded sentences do is they don’t stand for the ordinary things they stand for. They stand for the ideas, and I’m using ideas now, or concepts, or what is the official word was senses that people grasp when they think about those things.

Ray Briggs
So what is the relationship between the logic that Frege was doing and the idea of like trying to understand how people think, or what’s inside people’s heads?

John Perry
Well, Frager didn’t say too much about what is inside people’s heads, except mainly the point that his concepts were not inside people’s heads. Frager thought that there were three realms. Two of them form the causal realm, the physical realm and the mental realm. And then there was a third realm, which is a realm of abstract objects that don’t change, and don’t have any causes and don’t have any effects, more or less. And what he called thought, fences, concepts, numbers, those were all in the third realm.

Ray Briggs
Those are the things that I’m talking about when I say that, Lois believes that Superman wears a cape.

John Perry
Well, so, when you say Superman wears a cape, you’re talking about Superman, who’s wearing a cape that’s in the physical world. When you say, Lois believes the Superman wears a cape, you’re talking about her beliefs that’s in the middle world. But when you get to the part where you’re describing the kinds of beliefs that Superman wears a cape, you’re talking about senses, the senses she grasps when she thinks about Superman. I mean, in, you know, a simple way to put it, she thinks Superman has certain identifying properties. And when she thinks about Superman, she’s thinking about the guy with those identifying properties. And those aren’t the same ones she associates with Clark Kent. So that’s she can think she’s thinking about someone else when she’s thinking about Clark Kent. But with Frege that’s a little more complicated because it involves grasping senses, Lois grasps senses, and thus grasps what we call propositions and he called thoughts. So we got the proposition that Superman wears a cape, we’ve got the proposition that Clark Kent wears a cape. When Lois grasps the proposition that Superman wears a cape, she’s really grasping the proposition that something like, there’s one and only one man from Krypton that has arrived here in Manhattan or wherever it was, to help us put out fires and who can jump over tall buildings, the one man bound, and he wears a cape. And when she thinks Clark Kent wears a cape, she’s thinking ah, there’s one man who’s a timid schmuck that works with me at The Daily Planet, is afraid of his own shadow and probably has never changed clothes and clothes in his life, although I guess she didn’t know Superman did either. So those are two different thoughts composed of different senses. And that’s all the third realm. But then those sensors pick out different individuals in the causal realm, except they don’t pick out that they were individuals, they both pick out the same individuals.

Josh Landy
That was very clear, John. John, we received an email all the way from Perth in Australia from Tom. Tom asks how Frege his work relates to other works of philosophy such as Wittgenstein’s Tractatus and Philosophical Investigations, as well as the work of Richard Rorty.

John Perry
Well, I’ll try two out of three. Okay, so [unintelligible] and Wittgenstein both studied with Frege in the later part of his life in the early 1900s, before World War Two in Wittgenstein’s case, because he served in World War Two. And he had a deep influence on both of them. Now, [unintelligible] tried to take Frege’s basic ideas of sense, reference, logic, and broaden it to a whole philosophical theory. And he basically said, look, I mean, philosophy, a lot of what people say in philosophy is nonsense. But insofar as it is sense, we can kind of see it in this Fregeian system. And then he had a philosophy of science that involves local verifiability, which is really not so much a Fregeian idea. And, and he was quite influential, he’s very influential on Klein. So this Fregeian influence, this basic idea of sentences with meanings or sentences that have truth values, and so forth and so on, that influenced all these guys. Now Wittgenstein was a bit different, while he was serving in World War One for the German and the German side of things, had already read Frege, read some Russell and he tried it. The Tractatus was an attempt, comes close to being an attempt, to developing a metaphysics and epistemology that goes with Frege’s Begriffsschrift. The later Wittgenstein was still deeply influenced by Frege, but he was deeply influenced, I think that the whole project was kind of misconceived, that you really can’t understand language in terms of this perfect logic that Frege was putting together, you have to understand language in terms of the social roles that people play and how they use words to help them do that. And Rorty, who was a nice guy who lived in Stanford and read a lot of Derida.

Josh Landy
And loved Monty Python. You’re listening to Philosophy Talk. Today we’re thinking about Frege and the language of reason with John Perry, author of “Frege’s Detour.”

Ray Briggs
What legacy has Frager left behind? How did his ideas lead to the development of modern computer science? After all these years, have we gotten any closer to building the perfect logical language?

Josh Landy
Logic, language and computer technology? Plus a listener question from our community of thinkers when Philosophy Talk continues.

Can logic finally tell us who we are, if only we had the right language? I’m a series of numbers and squiggles that mean Josh Landy. And this is Philosophy Talk, the program that questions everything

Ray Briggs
except your intelligence. I’m Ray Briggs. Our guest is our old friend John Perry and we’re thinking about Frege and the language of reason.

Josh Landy
So John, you’ve written that Frege’s ideas are still influential today. Could you say something about how they’ve shaped fields like computer science?

John Perry
Well, yeah, so if I look at Frege’s phases, the first phase was The Begriffsschrift, to which I think he did a wonderful job coming up with a wonderful logical language. His second phase was when he wrote on sense and reference and other things, when he backed away from some of the things he said in The Begriffsschrift and gave us this wonderful way of looking not so much at logic but as the issues in the philosophy of language. But his real ambition, and what those things were subsidiary to, was to develop arithmetic as an extension of logic, to show that the basic rules of arithmetic really were theorems in his logic, the theory of sense and reference well, it’s really a way of putting aside things that he thought were difficult, but not necessary to think about for this project that Russell called [unintelligible] suppose reducing arithmetic to logic. And then he wrote a two volume book, The Grundgesetze that he thought did the trick.

Ray Briggs
So did he succeed?

John Perry
No. After the first volume was published, and just as the second volume was coming out, Russell wrote him a little letter that said, By the way, Gottlob, or however they talk to each other. One of your axioms in your Grundgesetze is wrong. Now, The Grundgesetze, in order to succeed, had to forge a link between logic and what we now call set theory. Frege and others were inventing set theory at the time, but that’s what he needed, because he needed to reduce numbers to something that weren’t numbers. And so he thought that two was the set of two membered sets.

Ray Briggs
So I know that Frager loved this thing about, “we’re not really talking about objects, we’re talking about concepts.” But why think that two is the set of all two membered sets?

John Perry
Well, it gives you a way of not introducing an object two as kind of like just a new object that you just found, like the Pacific Ocean or something. Instead, you’ve got this notion of a set, which you understand very well, because it all comes out of logic. What’s the thing about the numbers? Well, you got this order from one to, you know, forever. And other things you can do with numbers. And it turns out, for instance, you can do all those things with sets. And when you do missense, you understand what you’ve got. So if you start with a set of nothing, call it zero, start with a set that has one thing in it, call it one, start with a set that has zero and one at it, call it two, that all works out. I’m not sure that that’s not exactly the way Frege did it. But the point is that he needed set theory. And he thought he had set theory. But Russell says, no, you don’t. Because your axiom, one of your key axioms is if you have a predicate, then you have a set containing just those things that fall under the predicate. So Philosophy Talk hosts, well, we got a set consisting of Josh, and Ray. And as I said, a Philosophy Talk host contains all only the people to whom that predicate applies. Russell said, “What are you going to do about the set that contains all sets that don’t contain themselves?” If theset contains itself then it doesn’t contain itself, because it’s not the right kind of thing that can be contained. If it doesn’t contain itself, then it doesn’t contain all the things that don’t contain themselves. He was apparently very depressed by this.

Josh Landy
Oh, yeah. I’m not surprised. You know, so this is, I’m a Brit. So we specialize in heroic failures. And I’m also a literature guy, we love big dreams. I take it, of course that, you know, the dream failed, right? So Russell show that it couldn’t pan out. But I’m really curious about what he was dreaming. Mikey, it feels almost like Leibniz’s idea that you could invent a universal language. It’s kind of like a mathematical calculus. Every reasoning would be mathematical, it would allow us to, to know everything with certainty. You know, you’d only have calculation errors, everyone could understand every argument. And Frege had this line, right? If we, if we could only express a thought correctly, there’d be no ambiguity. So what was even if the dream didn’t totally pan out, John, what was the dream? What did he hope he could achieve with this, with this new way of expressing things?

John Perry
So this dreamer phrase, the failure had a tremendous effect, because it brought to the fore, a lot of issues in set theory, mathematics, and logic, and some very bright people like Alonzo Church, Alan Turing, and Rudolph Carnap, and all sorts of other people, including the people we call the Vienna Circle now, got involved in them The Carnap thing went off mostly on the philosophy of science. Turing went off on the development of computing. But I think if you go back and retrace another way, he could have gone after The Begriffsschrift that incorporates lots of his insights in “On Sense and Reference,” but doesn’t abandon the idea of a circumstance. It turns out very well. Now, this is what barwise Jon Barwise and I argued in our 19, whatever it was, book “Situations and Attitudes,” and a few people believe this some so maybe more people will believe this, although he’s now unfortunately, deceased, but, you know, I tried to straighten a few more things out. I think it’s a combination of The Begriffsschrift and insight from his later works leads to a really interesting philosophy of language. Could I tell a story?

Ray Briggs
Yes, yes, please.

John Perry
When we started CSLI, Jon Barwise and I and Tom Wasow and Ivan Sag and some others, was supposed to be, and still is, combination of computer scientists, logicians, mathematicians, psychologists. So to inaugurate it, we invited Alonzo Church down to give us the talk. Now, Church and I had been friends at UCLA. So he knew me not particularly well, because I was sort of a youngster compared to him. And John Etchemendy, later our provost for 40 or 50 years, was an assistant professor in philosophy and I sent him up there to get Church at the airport and drive him down. And on the way, Church said, well what is the CSLI thing? And Etchemendy said, well, it has a lot to do with logic. So that’s, that’s why we really want you to get started. But it also has to do with the computer science. And Church said, computer science computer science. I had a student that was very interested in computer science. His name was Alan Turing, ever heard of him? So he told that story and see, Church had quite a sense of humor. So I think he was probably kidding, to ca ertain extent.

Josh Landy
Well, John, thank you so much for joining us today and for solving all of our logical puzzles. It’s been great to have you back.

John Perry
It was great being on Philosophy Talk again, I love the program.

Josh Landy
Thanks for that plug. And thanks so much again for joining us today. Our guest has been John Perry, Professor Emeritus of Philosophy at Stanford University, and author of “Frege’s Detour: An Essay on Meaning, Reference and Truth.” So Ray, what are you thinking now?

Ray Briggs
Well, John, some of the conversation about logically perfect languages, at the end, reminded me of a book that I really enjoy by Arika Okrent called “Land of Invented Languages.” It’s a 2009 book, and it’s about a bunch of imaginary languages, most of which aren’t trying to do what Frege was doing, although some of them were. Some of them, like the one invented by John Wilkins, was trying to reason about any subject matter clearly. And then there’s one called lodge band that I think owes a lot to Frege. So it’s a fun book to pick up if you enjoyed this show.

Josh Landy
Such beautiful dreams, and wouldn’t it be great if they came true one day? Thanks for the great reading recommendations. So we’re going to put a link to that and also everything else we’ve mentioned today, on our website, philosophytalk.org, where you can also become a subscriber and get access to our library of more than 500 episodes.

Ray Briggs
And if you have a question that wasn’t addressed in today’s show, we’d love to hear from you. Send it to us at comments@philosophytalk.org and we may feature it on the blog.

Josh Landy
Of course, sometimes we get questions not related to a particular episode. So Ray, why don’t you and I dig into one of those questions from the community?

Kysung
My name is Kysung. And I’m from Vietnam. And my question is, can the world declare war? By virtual reality? And can virtual reality end the real war? And can it help many lives to be spared? And end the war finally, for the next generation?

Josh Landy
So what do you think, Ray?

Ray Briggs
I really love the idea of ending war by virtual reality. I think it’s it’s a wonderful thought. But I’m not really convinced that it’s going to happen, because I think we already have the technology to do something like it and we haven’t ended war. Because I think something like sports is a form of symbolic combat. Like there are lots of sports where different nations compete against each other. And unfortunately, this hasn’t replaced war, even though it’s a kind of symbolic way for us to defeat other nations.

Josh Landy
Instead, you just get hooliganism, so you get more violence.

Ray Briggs
Hooliganism, and you still haven’t ended the military in any country.

Josh Landy
Right? Yeah, I also have a kind of worry. I mean, obviously, yes. Imagine if you could just solve these disputes with nobody losing life or limb. But, you know, I worry that that the warring parties wouldn’t consider the matter settled, you know, it’d be like best of three, best of five, best of seven. Like, how would you know, does it count? Would it feel like it counted? If there wasn’t an actual occupation of territory with bodies or something like that? You know, that’s, I mean, our former colleague, Sepp Gombrich, that’s how he defined power, the ability to occupy space and bodies. And if I guess if that’s what two nations are trying to do, right, to seize power or to defend, right, against a hostile power, maybe, maybe you can’t do it in the virtual.

Ray Briggs
Yeah, I mean, a thing like I think about what you’re saying is that I think it brings out that if you want to do any kind of virtual war, or like symbolic war, you need some degree of cooperation, because you have to agree on the rules. I think one problem with virtual war is suppose that my country loses the virtual war and also has weapons that it could use to invade the country that it lost too. You might ask like, why wouldn’t I invade? Like, if I actually cared about not wreaking war on other countries, I wouldn’t invade, but the politicians with access to weapons generally don’t care that much.

Josh Landy
One thing I love about it, I love a lot of things about the idea, but one of the things I love about it is that it kind of harkens back to this ancient notion of the champion warfare, right? Where you have these two warring communities, and they each pick a champion like David and Goliath, and it’s single combat, and whoever wins, they win for their community. And you see those stories in the Bible, and person stories of China, and French medieval stories. But I think the problem with that is that, you know, in those contexts, there was often a belief that, it certainly is the case in these medieval French stories, there’s a belief that, like, if you win the duel, that proves God is on your side. And so that this isn’t just a kind of strength battle. It’s like, if, you know, if God’s with me, I will kill you. And if God’s with you, you will kill me. And so there’s a kind of reason to accept the outcome. But do you think there are many nations that hold that belief today?

Ray Briggs
So not that belief, but I actually don’t think it’s complete chaos. So I mean, I think that a lot of philosophers are interested in just war theory, which like, you might either sometimes worry that this is an oxymoron. Like, once you’re in the business of killing people, are you really doing anything just, but there are certain things that we have the power to do, but that we don’t do? Because they are morally wrong? And it’s sort of a different, like, I think, like I agree that it is morally wrong to use chemical weapons, or to attack civilians. And you know, I guess, like the attacking civilians is maybe something that I wish people never did, but they do. But I do think that people even in war see themselves as bound by some moral constraints.

Josh Landy
Yeah, before we wrap up this segment, let me push one version of a positive response to this question, which actually came to me from a colleague David Palumbo-Liu. I was talking to him about this. And, and he suggested, well, if you were to play this virtual game, until the resources of one country ran out, imagine a game that would use a lot of human power, a lot of energy power. And ultimately, one of these countries would be, you know, just drained in some kind of way of resources. Maybe could that work?

Ray Briggs
It sounds more effective. I think I worry about whether it’s more ethical then. So if a bunch of people from the losing country end up dying, not because they were killed, but because they were starved or didn’t have enough clean water? I don’t know that that’s like a great outcome.

Josh Landy
Right. Thank you so much Kysung, for sending in that brilliant question all the way from Vietnam.

Ray Briggs
If you’ve got a question in your own life, that’s bedeviling, a conundrum that might benefit from some philosophical insight, send it to us at conundrums@philosophytalk.org, and we may talk it through with you on the air.

Josh Landy
Philosophy Talk is a presentation of KALW local public radio San Francisco, and the trustees of Leland Stanford Junior University. Copyright 2021. Our executive producer is Tina Pamintuan, the senior producer is Devon Strolovitch. Laura Maguire is our Director of Research. Cindy Prince Baum is our Director of Marketing.

Ray Briggs
Thanks also to Merle Kessler and Angela Johnston.

Josh Landy
Support for Philosophy Talk comes from various groups at Stanford University and from the partners that are our online community of thinkers.

Ray Briggs
The views expressed or misexpressed on this program do not necessarily represent the opinions of Stanford University or of our other funders,

Josh Landy
not even when they’re true and reasonable. The conversation continues on our website, philosophytalk.org, where you can become a subscriber and get access to our library of more than 500 episodes. I’m Josh Landy

Ray Briggs
and I’m Ray Briggs Thank you for listening.

Josh Landy
And thank you for thinking.