Quick science news

1. Dr Fatima Ebrahimi has invented a new fusion rocket thruster concept which could power humans to Mars and beyond.

2. A team of researchers led by scientists at Tel Aviv University say they may have stumbled upon the “Achilles’ heel” of cancer cells, which could in the future lead to the development of an entirely new array of cancer drugs and treatments.

Kwisatz Haderach, give the dog a bone ...

They've actually discovered there were giant prehistoric sand worms. "Giant" meaning about two meters long. They were predatory, lived on the ocean floor, and existed about 20 million years ago. The spice must flow.

The Lucas-Penrose Argument

Brace yourselves, this one can melt your brain.

In the early 20th century, it was thought that mathematics could be made into a complete formal system. This is a system in which every element has a complete definition, every entailment is deductive (so that conclusions necessarily follow from premises), and which contains no contradictions. But some basic concepts are unformalizable. "Truth," for example, allows us to form the Liar Paradox: "This statement is not true." If it's true, then it's false, and if it's false, it's true. So no formal system can have a truth predicate in it. (This isn't a mark against truth, btw.) One motive for this is a system with a contradiction leads to the principle of explosion, since ex falso quodlibet -- from a contradiction, everything follows.

Anyhoo, Kurt Gödel, inarguably the greatest logician of the 20th century, suggested we use a concept in place of truth that IS formalizable and doesn't lead to a paradox: provability. "This statement is not provable" doesn't lead to a problem like the Liar Paradox. But since such a statement can be made within any formal system, and since any such system must involve deductive provability, it follows that there can be no complete formal system. This is the intuition behind Gödel's Incompleteness Theorems. We'd been chasing a mirage.

This was around 1930. About the same time we had huge strides made in artificial intelligence by the likes of Alan Turing, Alonzo Church, etc. Turing came up with the idea of a Turing machine, which is an instantiation of a formal system, the cause-and-effect processes of the machine standing in for the deductive ground-consequent relations of the formal system. But since any formal system will have a statement within it to the effect of "This statement is not provable within this system" (called a Gödel sentence), such would also have to be the case for a Turing machine.

This is a problem because a Turing machine can only affirm provable claims, so any given machine will have a Gödel sentence which it cannot affirm. Human minds, however, have no such limitation: we can see that there is a Gödel sentence within our own systems of thought and affirm it, recognizing that it is correct. It is correct that "This statement is not provable within this system" is not provable within that system. This has two consequences: 1) Human minds cannot be reduced to Turing machines. They cannot be fully explained by the mechanistic cause-and-effect processes that are going on in the brain. There is an element of the mind that goes beyond it, and this element is truth-conducive. 2) Turing machines, and artificial intelligence in general, cannot fully duplicate the processes of human minds. They may be able to duplicate the end-products, but they can't produce them the same way that human minds do: through non-deductive (non-formal) reasoning. They can only do it via mechanistic cause-and-effect processes which don't have to be truth-conducive in order to arrive at those end-products.

This conclusion was reached by Gödel himself in his 1951 Gibbs Lecture, "Some Basic Theorems on the Foundations of Mathematics and Their Implications", but it wasn't published until the third volume of his Collected Works came out in 1995. J.R. Lucas -- who in writing this post I have learned passed away earlier this year, which devastates me -- however, wrote an enormously influential essay in 1961, "Minds, Machines, and Gödel" which presented the same idea. It motivated a lot of objections which Lucas responded to in philosophy journals, and then he published his book "The Freedom of the Will" in 1970, the last third of which is on the implication of Gödel's Incompleteness Theorems for the mind and AI. You can read most of his essays online at https://web.archive.org/web/20160718073705/http://users.ox.ac.uk/~jrlucas/. Later, mathematical physicist Roger Penrose defended the argument in his own way in his books The Emperor's New Mind and Shadows of the Mind.

Simple, no?

Space news

A probe will touch down for just a few seconds on 101955 Bennu, an Earth-crossing asteroid, in less than a month, collect some samples, and then return to Earth in 2023. That is pretty cool. It'll look something like this (try to ignore the soundtrack):

Some recent acquisitions

Nonfiction:

William Alston, Perceiving God: The Epistemology of Religious Experience. (I should have read this one years ago. Written by one of the most important epistemologists of the last hundred years.)

Nathan Aviezer, In the Beginning: Biblical Creation and Science. (A Jewish perspective.) 

Raymond E. Brown, The Virginal Conception and Bodily Resurrection of Jesus. 

Frederick Copleston, Aquinas: An Introduction to the Life and Work of the Great Medieval Thinker. 

Charles Darwin, From So Simple a Beginning: Darwin's Four Great Books (Voyage of the Beagle, The Origin of Species, The Descent of Man, The Expression of Emotions in Man and Animals), edited by Edward O. Wilson. (Unfortunately, it doesn't include The Formation of Vegetable Mould Through the Action of Worms, with Observations on their Habits, so I'm kinda bummed.)

Cardinal Avery Dulles, A History of Apologetics. (I've been wanting this one forever.)

The Interlinear NIV Hebrew-English Old Testament. (Almost 3,000 pages. Got it for about $25.)

Robert Jastrow, God and the Astronomers. (I had this years ago and it was lost in shipping when we moved back to the States.)

John Lennox, God's Undertaker: Has Science Buried God? 

C.S. Lewis, The Discarded Image: An Introduction to Medieval and Renaissance Literature. (One of the few Lewis books I didn't have, although I've read it more than once.)

Alister McGrath, Iustitia Dei: A History of the Christian Doctrine of Justification. (OK, this one I've really wanted forever)

_______, Darwinism and the Divine: Evolutionary Thought and Natural Theology.

_______, The Science of God.

Arthur Schopenhauer, The World as Will and Representation, 2 volumes. (I love Nietzsche, and my impression of Schopenhauer is that he's a forerunner of Nietzsche who was more pessimistic.)

Wilbur Marshall Urban, The History of the Principle of Sufficient Reason. (This was published in 1898, so as a history it's a little out of date. I'm just a big fan of Urban.) 

Fiction:

Jorge Luis Borges, Collected Fictions. (This is all of his short story collections in one volume.)

Fredric Brown, From These Ashes: The Complete Short SF of Fredric Brown. (Gold.)

Ted Chiang, Exhalation. (Short stories, and the ones I've already read are amazing. The title story is incredibly relevant to philosophy of mind.)

James S.A. Corey, Leviathan Wakes.

_______, Caliban's War.

_______, Abaddon's Gate. (I've watched The Expanse, the show based on these books, and loved it, but the books were expensive. I got these first three as a boxed set for about $20 which is much cheaper than I've seen any of them.

Cixin Liu, The Wandering Earth. (His short stories. I've loved everything I've read from him.)

Ken Liu, Invisible Planets: Contemporary Chinese Science Fiction in Translation. (Chinese short stories that Ken Liu translated and edited. He also writes his own books and stories, so I'm going to give those a look in the near future.)

Fred Saberhagen, Love Conquers All. (Same author as the Berserker series. I wanted this one because Saberhagen was a Catholic and from what I understand, this is his version of Brave New World.)

John Scalzi, Redshirts.

Lucius Shepherd, The Best of Lucius Shepherd.

Michael Swanwick, The Dog Said Bow-Wow.

John Varley, The Persistence of Vision.

Peter Watts, Blindsight. (This supposedly has some philosophical relevance to the Chinese Room argument.)

Andy Weir, Artemis. (Same author as The Martian.)

Robert Charles Wilson, The Harvest.

This is interesting

 Entire cities could fit inside the moon's monstrous lava tubes. The lower gravity means the tubes are significantly larger than on Earth.

"The largest lava tubes on Earth are maximum [about] 40 meters [130 feet] of width and height," said study co-author Riccardo Pozzobon, a geoscientist at the University of Padova, Italy. "So like a very large motorway tunnel."

That's certainly big enough space for some people to fit inside. But on Mars collapsed lava tubes tend to be about 80 times larger than Earth's, with diameters of 130 to 1,300 feet (40 to 400 m). Lunar lava tubes seem to be still larger, the researchers found, with collapse sites 300 to 700 times the size of Earth's. Lunar lava tubes likely range from 1,600 to 3,000 feet (500 to 900 m).

A lava tube on the moon, Pozzobon told Live Science, could easily contain a small city within its walls.

Yes, I know, my love of science is fueled by my love of science-fiction. I just like the idea of giant caves on the Moon and Mars with cities inside them. Sue me.

The Plantinga/Dennett Debate with captions

This is the actual "debate" between Alvin Plantinga and Daniel Dennett. I put "debate" in quotes because there's not as much back-and-forth as a standard debate. It's just  Plantinga's presentation, Dennett's response, and Plantinga's counter-response. You can listen to it elsewhere online, but since the audio is so bad I went through it and added captions. Because I just care that much. (Also because I play it for my students and they couldn't follow it.) If anyone can figure out what Plantinga says at 9:52 let me know.

These three presentations later comprised the first three (of six) chapters in Science and Religion: Are They Compatible? (OUP) although Dennett changed several aspects of his presentation. Notably, in the book he doesn't include his "little joke" that he closes with (starting at 1:19:27). I guess it didn't play well with the audience and/or publisher. Dennett's interruption of Plantinga didn't make it into the book either (1:28:35 and following). The final three chapters of the book are Dennett's response to Plantinga's last presentation, Plantinga's response to that, and then Dennett's final response.

So this is my present to you. Merry Christmas. What'd you get me?

Eclipse

We drove south to be in the path of totality of the eclipse last Monday. It was pretty amazing. As we approached totality, the temperature dropped suddenly, and it started getting dark. But it wasn't the same kind of dark you see at twilight. At twilight, the sun's rays are hitting your position horizontally, which means they're travelling through a lot more atmosphere. Here, the sun's rays were almost vertical. So when those rays get blocked the darkness doesn't have the same feel to it.

And seeing the sun's corona was absolutely amazing. My sister-in-law pointed out that at about the eleven o'clock position, the corona was red instead of yellow. Patterico claims he saw a solar flare with his naked eye, which would be pretty amazing. It reminded me of this post where I pointed out that, for millennia, solar eclipses were the only way humankind could observe the sun's corona and so learn about the universe. In fact, there is no other place in our solar system where you can stand on one body and have another body block out the sun, but just barely enough to allow the corona to be visible. There are plenty of other examples like this where it seems like the earth and the universe are not merely set up to allow for advanced life but to allow for science. Another example from the linked post is that a planet has to be in a spiral galaxy and be between spiral arms. In just about any other place in any other type of galaxy, you wouldn't be able to see beyond the nearby stellar neighborhood, much less out of the galaxy.

At one point I realized that a partially eclipsed sun looks like the Cheshire Cat's smile. It was like an emoji in the sky. A smiling mouth. And if that mouth had suddenly puckered up, I would have said, "Eek! Lips!"

OK, I'll stop.

Visiting Venus

This is very interesting. NASA has developed electronics to withstand the conditions on Venus. Venus is closer than Mars, but because the atmosphere is so dense and the temperature so high -- it's about 90 earth atmospheres (like being 3,000 feet underwater) and hotter than Mercury -- it's a tad difficult to send anything to land there. The article points out that Venera 13 lasted 127 minutes on the surface, and that's the record. But if there are new forms of electronics that can survive there, the possibilities open up. Once, I was googling to find out the highest mountain on Venus (Maxwell Montes, 11 km high or 6.8 miles elevation) to see if we have the technology to survive there. The temperature there would only be 716 degrees Fahrenheit and the density would only be 44 earth atmospheres. I note that the Exosuit is good to about 30 atmospheres (equivalent to about 1,000 feet underwater). However, if we had a motive, I'm confident the technology would be forthcoming. Of course if your Venus suit failed ... that ... that would suck. At any rate, if we have electronics we can put off sending people down there right away. We can have a manned habitat in orbit that sends down probes, even probes that can return. Or we can even go further and have never-landing aircraft in Venus's atmosphere. In fact, that would probably be the closest to earth conditions anywhere in the solar system. If you had the aircraft at the elevation that's one atmosphere, you'd just need a breathing mask to wander out on the lanai. Geoffrey Landis, NASA scientist and science-fiction author, has written about this possibility.

The EM drive and abductive reasoning

I've mentioned the EM drive before and how it seems to violate Newton's third law. I hope it works because it would be a boon for space exploration. A recent Popular Mechanics article discusses it and summarizes its apparent incongruity with contemporary physics: "It's much more likely that the researchers are overlooking something than that much of our physics is wrong." Yes indeedy. That's called abductive reasoning or inference to the best explanation. The classic example is when astronomer's noticed that Uranus's orbit was not following the path Newton's laws dictated. The two explanations were that a) Newton's laws were wrong, or b) there's a gravity well somewhere out there pulling Uranus out of orbit. They calculated where the gravity well would be, pointed their telescopes there, and bingo! -- that's how Neptune was discovered.

Of course abduction is not absolute like deduction or even as strong as induction. Take three possible arrangements of three elements: X; Y; and XàY.

Deduction:
XàY
X
∴Y

The first premise states the law XàY: if X is the case, then Y is the case. The second premise affirms that X is the case. Therefore Y is the case; in fact Y must be the case. All hail deduction! This is a pretty standard conditional syllogism, modus ponens in particular.

Induction:
X
Y
∴XàY

The first premise is that X is the case. The second is that Y is the case. We can take this to mean that whenever X is the case Y is also the case -- that is, whenever X is observed, Y is observed following it. So the conclusion is the law  XàY. Of course, this could fail to be the case: induction is not deductively valid. If it were, we would call it deduction. As stated, this may commit the fallacy of post hoc ergo propter hoc (after this, therefore because of this). Perhaps X and Y occur together for something other than a strict causal relation flowing from X to Y. But the above formulation is just meant as an illustration.

Abduction:
XàY
Y
∴X

The first premise states the law, if X is the case then Y is the case. The second premise affirms that Y is the case. From this we abductively infer that X is the case. This pretty clearly commits the deductive fallacy of affirming the consequent -- or would commit it if it were being presented as a deduction. It would also commit the inductive fallacy of post hoc ergo propter hoc -- if it were induction. The idea here is that we have a store of possible explanations for Y. We know the law, if X then Y. Therefore, one possible explanation of Y is X. Again, this is not deductively valid, but so what? We have several potential explanations for Y, X is available and is in fact the best explanation, so we abductively infer X.

Science constantly uses abductive reasoning; in fact, scientists were doing so for centuries before C.S. Peirce, a.k.a. the patron saint of philosophers of science, explained and validated it (this is one reason why you can't really study the philosophy of science without also studying the history of science). But it works enough of the time to justify its use. You can observe abductive reasoning in action by watching or reading any of the incarnations of Sherlock Holmes, despite the constant claims that he is using the science of deduction.

So, back to the EM drive. As with Uranus's orbit, the two possible explanations are that Newton's laws are wrong or we're missing something. The latter is much more likely, so absent further information, the best explanation is that Newton's third law is not being violated but that we are just not observing its application for some reason.

And this could be wrong. The example of Uranus's orbit is usually discussed alongside a similar problem with Mercury's. Newton's laws dictated that Mercury's orbit should follow a certain path and it wasn't. Easy! There's another gravity well between Mercury and the Sun that's pulling it out of its orbit. Except there wasn't. It turned out that the explanation here is that Newton's laws were wrong (or I would say, contra Thomas Kuhn, that Newton's laws needed to be supplemented for certain domains of measurement). We needed Einstein's theories of relativity to make sense of Mercury's orbit. Something like that could be the case with the EM drive, but again, it's probably not the best explanation. Yet.

BS

Some University of Washington philosophers are teaching a course this coming spring term on critical thinking. A very specific aspect of critical thinking. Their course title is "Calling Bullsh*t" without the asterisk. Right away, though, I'm disappointed. In their syllabus, the second week's required reading will be a chapter from Carl Sagan's The Demon Haunted World: Science as a Candle in the Dark. But Sagan was as much a purveyor of bullsh*t as anyone, especially when accusing others of purveying bullsh*t. The title of that book is one example. Here's another. A third can be found in Dennis Danielson's essay "Copernicus and the Tale of the Pale Blue Dot" which does not seem to be online anymore. People who laud themselves as skeptics are only skeptical about what they want to be skeptical about.

(cross-posted at Quodlibeta)

Cool

The US Navy has found a way to make jet fuel out of seawater.

This is so cool

They're planning to bring extinct animals back to life, starting with carrier pigeons and moving on from there. Neologism of the day: de-extinction.

Derrida's revenge

Remember the Sokal hoax? Physicist Alan Sokal wrote a nonsensical article, filled with postmodern gibberish and a few scientific terms tossed in and submitted it to a postmodern journal. The article had no meaning whatsoever. They accepted it and published it. Many scientists and philosophers saw this as justification of their belief that postmodernism was nonsense on stilts and that no actual claims were being made. Jacques Derrida was a particular target of their ire: Quine, Searle, and others strongly objected to Derrida's acclaim, arguing that he was just moving words around without saying anything. I've seen challenges to Derrida's supporters asking what difference does it make when we rearrange the paragraphs in his essays. And then we have the glorious Postmodern Generator: every time you click refresh, a new, unique, and totally meaningless postmodern essay is produced.

I'm an analytic philosopher, so my sympathies are partially on the side of the critics. However, I think their objections are far too strong. A great deal of Continental philosophy is wonderful and meaningful. For some such philosophers exactitude is a failing, so they do not produce in-depth analyses: rather they speculate. And it is often very difficult to understand precisely what is being said. But there are analytic philosophers who are fairly indecipherable as well, such as Quine himself, or Millikan. A lot of it becomes so technical that it is impossible for the uninitiated to understand. So I guess I'm willing to give the Continental philosophers the benefit of doubt in thinking that, insofar as I don't understand them, it's because I'm effectively one of the uninitiated.

I'm bringing this up because of a very disturbing story. Two academic publishers are removing 120 scientific articles from their databases that are nonsensical gibberish. They were produced the same way the Postmodern Generator produces essays, through a computer program to make the articles seem like they're saying something when they're not. The articles were published between 2008 and 2013. So this seems to be comeuppance of those who promote the Sokal hoax and the Postmodern Generator: allegedly the same thing can be done with scientific papers.

There are two mitigating factors, however: First, they were not published in academic journals, they were published in conference proceedings. Such publications often do not have any peer review, and so it's not as if the nonsense went through this process and went unnoticed. In fact, many conferences do not require submissions to be in the final form of the essay or presentation that will be presented. All one has to do is submit a short abstract summarizing the essay, and if it's accepted, then whatever you present will automatically be accepted into the conference proceedings. If the "authors" who used the computer program to construct meaningless papers wrote a meaningful abstract, then the paper is automatically slated to be published. And of course, many conferences are desperate for presenters, so they'll accept virtually anything that's submitted. So even if the abstracts were just as meaningless as the papers, the conference organizers may have just glanced at it and accepted it.

Second, all of the papers in question were "authored" by Chinese people, and perhaps the organizers of the conference gave them the benefit of doubt and thought that the incoherence was just a non-native English speaker struggling to explain complicated subjects. In other words, maybe they did the same thing I do when I read Continental philosophy that I don't understand. This only goes so far though: if the papers were literally meaningless, at some point you think you'd notice that nothing is actually being asserted.

Still, despite these caveats, I'm a little floored by this. I kind of chuckle about the Sokal hoax, but when I read about this I immediately tried to find some reason to explain it away. I'm just unable to believe that it's a general problem, whereas with the pomo stuff I wouldn't be that surprised if it was. I also have to say that the editors of these conference proceedings, as well as all the other contributors, now have black marks on their CVs, and I think that shows how immoral these acts were. The editors were trying to participate and contribute to academic thought, and now their names are associated with gullibility, fraud, and an uncritical attitude, all of which are verboten in academia. The "authors" of these articles have harmed a lot of people. Of course, that was also the case with the Sokal hoax, but for some reason, I never really thought about it there.

Two more must-reads

"Leibniz on Natural Teleology and the Laws of Optics", Philosophy and Phenomenological Research 78/3 (2009): 505-44, and "Leibniz's Optics and Contingency in Nature", Perspectives on Science 18/4 (2010): 432-55, both by Jeff McDonough. Biology and similar sciences impute functions to structures, organs, and organisms, and the concept of function is expressly teleological. McDonough's essays look at how Leibniz argued that teleology attaches itself to the harder sciences as well, such as physics and chemistry. Very interesting.

A long voyage

A year ago (and since) I wrote that Voyager 1 may have left the solar system. It has now been confirmed. Of course, one may reject the definition of solar system that's being used here -- Voyager 1 isn't beyond the orbit of the Oort Cloud, a sphere of asteroids and comets that orbit the sun out to about a light year's distance. Still the working definition is a good one, and it's absolutely amazing that a man-made object is now effectively in interstellar space -- and still working.

Some other interesting science news:

1. NASA has identified three asteroids for potential capture. That is, they'll go get them, and bring them into orbit around the Moon. Pretty cool.

2. Biologists have discovered functioning mechanical gears in an insect. Actual cog wheels. This is more than pretty cool. This is mind-boggling.

OK, this is interesting

I copied the link to this article a month ago and then forgot to blog about it: Water Trapped For 1.5 Billion Years Could Hold Ancient Life.

Scram

The US Air Force is continuing their successful investigations into scramjets. The most recent example is the X-51A Waverider which traveled 230 miles in six minutes. Prior to their recent string of successes, the longest a scramjet had ever worked was about ten seconds before melting, and now they're shutting them down deliberately. I'm really excited about this: it's an old technology that was abandoned in favor of other areas of research that is finally being given the attention it deserves. While we're on that, you might want to check out Vintage Space which I also have listed on the sidebar.

Fraudulent

Here's a fascinating article on Diederik Stapel, the Dutch psychologist who was discovered to have made up most of his research a couple of years ago. People just couldn't believe that a social scientist of his standing could have engaged in such extensive academic fraud, and that allowed him to get away with it for a lot longer. Some of the fraud found its way into the Ph.D. dissertations of his students, which is just a horrible thing to do, taking away their life's work from them, although he seems to have some idea of the magnitude of what he has done now.

Quote of the Day

At this point an annoying, though obvious, question intrudes. If Skinner's thesis is false, then there is no point in his having written the book or our reading it. But if his thesis is true, then there is also no point in his having written the book or our reading it. For the only point could be to modify behavior, and behavior, according to the thesis, is entirely controlled by arrangement of reinforcers. Therefore reading the book can modify behavior only if it is a reinforcer, that is, if reading the book will increase the probability of the behavior that led to reading the book (assuming an appropriate state of deprivation). At this point, we seem to be reduced to gibberish.

A counterargument might be made that even if the thesis is false, there is a point to writing and reading the book, since certain false these are illuminating and provocative. But this escape is hardly available. In this case, the thesis is elementary and not of much interest in itself. Its only value lies in its possible truth. But if the thesis is true, then reading or writing the book would appear to be an entire waste of time, since it reinforces no behavior.

Skinner would surely argue that reading the book, or perhaps the book itself, is a "reinforcer" in some other sense. He wants us to be persuaded by the book, and, not to our surprise, he refers to persuasion as a form of behavioral control, albeit a weak and ineffective form. Skinner hopes to persuade us to allow greater scope to the behavioral technologists, and apparently believes that reading this book will increase the probability of our behaving in such a way as to permit them greater scope (freedom?). Thus reading the book, he might claim, reinforces this behavior. It will change our behavior with respect to the science of behavior (p. 24).

Let us overlook the problem, insuperable in his terms, of clarifying the notion of "behavior that gives greater scope to behavioral technologists," and consider the claim that reading the book might reinforce such behavior. Unfortunately, the claim is clearly false, if we use the term "reinforce" with anything like its technical meaning. Recall that reading the book reinforces the desired behavior only if it is a consequence of the behavior. Obviously putting our fate in the hands of behavioral technologists is not behavior that led to (and hence can be reinforced by) our reading Skinner's book. Therefore the claim can be true only if we deprive the term "reinforce" of its technical meaning. Combining these observations, we see that there can be some point to reading the book or to Skinner's having written it only if the thesis of the book is divorced from the "science of behavior" on which it allegedly rests.

Let us consider further the matter of "persuasion." According to Skinner, we persuade ("change minds") "by manipulating environmental contingencies," specifically, "by pointing to stimuli associated with positive consequences" and "making a situation more favorable for action, as by describing likely reinforcing consequences" (p. 91f.). Even if we overlook the fact that persuasion, so characterized, is a form of control (a variety of "reinforcement") unknown to Skinner's science, his argument is in no way advanced.

Suppose Skinner were to claim that his book might persuade us by pointing to positive consequences of behavioral technology. But this will not do at all. It is not enough for him to point to those consequences (e.g., to draw pictures of happy people); rather he must show that these are indeed consequences of the recommended behavior. To persuade us, he must establish a connection between the recommended behavior and the pleasant situation he describes. The question is begged by use of the term "consequences."5 It is not enough merely to conjoin a description of the desired behavior and a description of the "reinforcing" state of affairs (we overlook, again, that not even these notions are expressible in Skinner's terms). Were that sufficient for "persuasion," then we could "persuade" someone of the opposite by merely conjoining a description of an unpleasant state of affairs with a description of the behavior that Skinner hopes to produce.

If persuasion were merely a matter of pointing to reinforcing stimuli and the like, then any persuasive argument would retain its force if its steps were randomly interchanged, or if some of its steps were replaced by arbitrary descriptions of reinforcing stimuli. Of course, this is nonsense. For an argument to be persuasive, at least to a rational person, it must be coherent; its conclusions must follow from its premises. But these notions are entirely beyond the scope of Skinner's science. When he states that "deriving new reasons from old, the process of deduction" merely "depends upon a much longer verbal history" (p. 96), he is indulging in hand-waving of a most pathetic sort.

Consider Skinner's claim that "we sample and change verbal behavior, not opinions," as, he says, behavioral analysis reveals (p. 95). Taken literally, this means that if, under a credible threat of torture, I force someone to say, repeatedly, that the earth stands still, then I have changed his opinion. Comment is unnecessary.

Skinner claims that persuasion is a weak method of control, and he asserts that "changing a mind is condoned by the defenders of freedom and dignity because it is an ineffective way of changing behavior, and the changer of minds can therefore escape from the charge that he is controlling people" (p. 97). Suppose that your doctor gives you a very persuasive argument to the effect that if you continue to smoke, you will die a horrible death from lung cancer. Is it necessarily the case that this argument will be less effective in modifying your behavior than any arrangement of true reinforcers?

In fact, whether persuasion is effective or not depends on the content of the argument (for a rational person), a factor that Skinner cannot begin to describe. The problem becomes still worse if we consider other forms of "changing minds." Suppose that a description of a napalm raid on a foreign village induces someone in an American audience to carry out an act of sabotage. In this case, the "effective stimulus" is not a reinforcer, but the mode of changing behavior may be quite effective, and, furthermore, the act that is performed (the behavior "reinforced") is entirely new (not in the "repertoire") and may not even have been hinted at in the "stimulus" that induced the change of behavior. In every possible respect, then, Skinner's account is simply incoherent. Since his William James Lectures of 1947,6 Skinner has been sparring with these and related problems. The results are nil. It remains impossible for Skinner to formulate questions of the kind just raised in his own terms, let alone investigate them. What is more, no serious scientific hypotheses with supporting evidence have been produced to substantiate the extravagant claims to which he is addicted. Furthermore, this record of failure was predictable from the start, from an analysis of the problems and the means proposed to deal with them. It must be stressed that "verbal behavior" is the only aspect of human behavior that Skinner has attempted to investigate in any detail. To his credit, he recognized early that only through a successful analysis of language could he hope to deal with human behavior. By comparing the results that have been achieved in this period with the claims that are still advanced, we gain a good insight into the nature of Skinner's science of behavior. My impression is, in fact, that the claims are becoming more extreme and more strident as the inability to support them and the reasons for this failure become increasingly obvious.

It is unnecessary to labor the point any further. Evidently Skinner has no way of dealing with the factors involved in persuading someone or changing his mind. The attempt to invoke "reinforcement" merely leads to incoherence. The point is crucial. Skinner's discussion of persuasion and "changing minds" is one of the few instances in which he tries to come to terms with what he calls the "literature of freedom and dignity." The libertarian whom he condemns distinguishes between persuasion and certain forms of control. He advocates persuasion and objects to coercion. In response, Skinner claims that persuasion is itself a (weak) form of control and that by using weak methods of control we simply shift control to other environmental conditions, not to the person himself (pp. 97 and 99).

Thus, Skinner claims, the advocate of freedom and dignity is deluding himself in his belief that persuasion leaves the matter of choice to "autonomous man," and furthermore he poses a danger to society because he stands in the way of more effective controls. As we see, however, Skinner's argument against the "literature of freedom and dignity" is without force. Persuasion is no form of control at all, in Skinner's sense; in fact, he is unable to deal with the concept. But there is little doubt that persuasion can "change minds" and affect behavior, on occasion quite effectively.

Since persuasion cannot be coherently described as the result of arrangement of reinforcers, it follows that behavior is not entirely determined by the specific contingencies to which Skinner arbitrarily restricts his attention, and that the major thesis of the book is false. Skinner can escape this conclusion only by claiming that persuasion is a matter of arranging reinforcing stimuli, but this claim is tenable only if the term "reinforcement" is deprived of its technical meaning and used as a mere substitute for the detailed and specific terminology of ordinary language. In any event, Skinner's "science of behavior" is irrelevant: the thesis of the book is either false (if we use terminology in its technical sense) or empty (if we do not). And the argument against the libertarian collapses entirely.

Not only is Skinner unable to uphold his claim that persuasion is a form of control, but he also offers not a particle of evidence to support his claim that the use of "weak methods of control" simply shifts the mode of control to some obscure environmental factor rather than to the mind of autonomous man. Of course, from the thesis that all behavior is controlled by the environment, it follows that reliance on weak rather than strong controls shifts control to other aspects of the environment. But the thesis, in so far as it is at all clear, is without empirical support, and in fact may even be empty, as we have seen in discussing "probability of response" and persuasion. Skinner is left with no coherent criticism of the "literature of freedom and dignity."

Noam Chomsky
"The Case against B. F. Skinner"
The New York Review of Books 17, no. 11 (Dec. 30, 1971)