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RS42 - On the Limits of Reason

Release date: August 28, 2011

Following up on their interview with Robert Zaretsky on the dispute between David Hume and Jean-Jacques Rousseau about the limits of reason, Julia and Massimo expand the topic to include a discussion of the failure of “foundational” projects (e.g., the quest for the ultimate bases of scientific reasoning, or of logic and mathematics). Also, our take on a recent paper on the evolutionary psychology of reasoning that has made mainstream news.

Julia's pick:  "Feeling Good: The New Mood Therapy"

Massimo's pick: "From Technologist to Philosopher Why you should quit your technology job and get a Ph.D. in the humanities"

Reader Comments (10)

I agree with Julia's argument for keeping the term "reason" for the practices aimed at getting to truth; we already have a term for the practices aimed at persuasion, and that's rhetoric. The Mercier & Sperber argument could then be presented as an argument that reason evolved in service to rhetoric, or for the primacy of rhetoric.

The argument you made on the podcast for the evolutionary benefits of truth (and thus of reason over rhetoric) works well for propositions with directly observable or temporally proximate consequences, but less well for those that are more theoretical, indirect, or distant. Rhetoric can more readily win over reason for such propositions, especially if acceptance of those propositions produces pragmatic benefits such as social stability. (Compare to Scott Atran's criticisms of reason's limits on the recent Point of Inquiry podcast.)

September 2, 2011 | Unregistered CommenterJim Lippard

Thank you very much for the podcast. I'm trying to get my head around the idea that this is an actual problem or whether it's much ado about nothing. Is the conclusion that Reason can't ultimately be grounded in an Absolute Truth? What cognitive, perceptive process can? If I understood Massimo correctly, he stated early in the show that if the justification for induction could be derived deductively, the “problem” for induction goes away. If, as was stated later in the show, deductive & axiomatic reasoning ultimately suffer the same fate (Godel's Incompleteness Theorem?), i don't understand how it could be considered a resolution. I also don't see how Julia's point about infinite regression is not applicable. Science doesn't make Absolute claims about Ultimate Truths because it can't. It minimizes the subjective, systematizes knowledge, allows us to make more accurate predictions about our future, gives us greater influence over the world around us and increases the avenues down which our minds may wonder. It does these things better than anything else we know of. Isn't that it's justification? Doesn't generalization work because all that we are and are apart of seem to have a common origin? It may not work tomorrow, but we'll have to cross that bridge if we come to it. I see the value in understanding any limitations, potential or realized, but is the goal here to arrive at a theory of knowledge that is unassailable? Reason 2.0? Is that even possible? Someday we may reach the limits of knowledge, but until then I say tally ho! How is this different from counting angels on the head of a pin?

September 2, 2011 | Unregistered Commentercew

Seems to me the problem of "ultimate justification" for one's mode of reasoning is insurmountable if you insist upon foundationalist epistemology, whether you are talking about induction, deduction, or the evidence of the senses and memory. We have to use our sensory apparatus and our brains to process information about the world, including information about the reliability of our sensory apparatus and our brains. We have to use deduction to prove deduction, and induction to prove induction (pace Popper, whose falsificationism still ended up introducing a notion of "corroboration" and thus an ineradicable "whiff of induction"). But that sort of circularity (or reflexivity) isn't necessarily vicious nor does it necessarily give undue credit--human investigation using these methods has demonstrated that they have limits, it hasn't granted carte blanche.

While I am extremely sympathetic to Damon Horowitz's views about knowledge of the humanities as a useful complement to engineering and the sciences, I have to question this claim in his article:

"If you are worried about your career, I must tell you that getting a humanities Ph.D. is not only not a danger to your employability, it is quite the opposite. I believe there no surer path to leaping dramatically forward in your career than to earn a Ph.D. in the humanities."

What does the empirical evidence actually show? In a recent article in The Economist (, it is claimed that "The premium for a PhD is actually smaller than for a master’s degree in engineering and technology, architecture and education. Only in medicine, other sciences, and business and financial studies is it high enough to be worthwhile."

BTW, my business card when I worked for Genuity in R&D gave my title as "Research Philosopher."

September 2, 2011 | Unregistered CommenterJim Lippard

Another followup on using deduction to prove deduction--there's a nice "Achilles and the Tortoise" dialogue in Douglas Hofstadter's Gödel, Escher, Bach where the Tortoise is asking Achilles to justify modus ponens without using it.

BTW, one of my former logic professors, Vann McGee, proffered a counterexample to modus ponens in the Journal of Philosophy in 1985, and Seth Yalcin has proposed a counterexample to modus tollens...

September 2, 2011 | Unregistered CommenterJim Lippard

I got the wrong book! Kindle only has "Feeling Good" by C. Robert Cloninger and I didn't look closely enough. Imagine my shock when I was reading Quantum Woo arguments for parapsychological phenomena! And an attack on James and Hume. The implication that epigenetics allows us to change our cells with our thought. Anyhoo. I figured out my mistake. Phew.

September 4, 2011 | Unregistered CommenterAaron

Massimo mentioned a book on Aristotle and cognitive behavioral therapy, does he recall the title? I'm interested in reading it.


September 8, 2011 | Unregistered CommenterMatus1976

"Our mathematics is determined by those axioms which best fit the world we happen to live in"

You're making the same mistake you have just been addressing about the foundations of science and logical positivism! Mathematics is only partly informed by the practical needs of the field of physics among many other things, and we can always question to what extent we should interpret its theories to be advancing toward some ultimate account of reality. If we look at mathematics as it also often relates to economics, we find that it is borne almost entirely out of financial interests and has little interest in any actual correlation with the world at all.

October 8, 2011 | Unregistered CommenterRyan

The concept of truth seems to be a contrived human abstract. We accept things as true when they can be demonstrated to fit our perception of reality. It seems to be just a term for interpreting information; a way of saying something is reliable or accurate. Understanding of truth seems to be always approximate, not absolute.

February 7, 2012 | Unregistered CommenterAndrew

Numbers are the Supreme Court of science. However Godel proved that we may not prove everything using numbers. Physics needs numbers. There must be Physics Foibles!! Name some.

March 11, 2012 | Unregistered Commentermelvin goldstein
Logical Induction may just amount to really fancy guessing.
January 30, 2018 | Unregistered CommenterJameson

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