About Rationally Speaking


Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Friday, December 30, 2005

How to think, a primer

This week I have been attending the annual meetings of the American Philosophical Association (Eastern Division) in New York, and the topic of thinking was, well, on everyone’s mind. While browsing through the book displays, I picked up a copy of Lewis Vaughn’s Writing Philosophy, which includes a nice little summary of the fundamental types of reasoning. Readers and commentators of this blog might want to keep it handy.

To begin with, of course, there is the fundamental distinction between deductive and inductive reasoning. Deductive reasoning is the type that is used largely in mathematics and formal logic, though it has a place in both science and everyday discourse. Deduction is the process by which one derives conclusions from a set of premises. If the formal structure of the deductive argument is correct, and the premises are true, the conclusion is guaranteed to be true. Of course, often enough some of the premises are questionable, or are derived from the other kind of logical reasoning (see below), which does not guarantee truth.

There are three fundamental types of deductive reasoning:

* Modus ponens (affirming the antecedent), where one proceeds as follows: (premise) if x then y; since x, (conclusion) therefore y. For example, if Socrates is a man, then he is mortal; Socrates is a man, therefore he is mortal.

* Modus tollens (denying the consequent): (premise) if x then y; not-y, (conclusion) therefore not-x. For example, if Socrates is a cat, then he has four legs; Socrates does not have four legs, therefore he is not a cat.

* Hypothetical syllogism: (first premise) if x then y; (second premise) if y then z; (conclusion) therefore if x then z. For example: Socrates is a man; all men are mortal; therefore Socrates is mortal.

The other fundamental kind of reasoning is induction, which is a way to come up with generalizations based on some initial observations. Inductive conclusions are powerful, and represent the basis of most science and everyday thinking, but – unlike deductive ones – are not guaranteed to yield truth, even if the premises are in fact correct and the reasoning is valid (i.e., formally correct).

Here are the three kinds of inductive reasoning:

* Enumerative, when one examines a sample and draws broader conclusions about the characteristics of the population from which the sample was taken. This is how much statistics, and of course opinion polls, work. The conclusions are strong in direct proportion to the size and representativeness of the sample.

* Analogical: this is reasoning by analogy, or metaphor. It is very common in both science and philosophy, and it can be illuminating. However, it is only as good as the analogy is relevant. Philosophers point out that some analogical reasoning contains what they call dis-analogies, i.e. parallels that actually do not stand up to scrutiny, and therefore undermine the conclusion. A classic example of disanalogy, as pointed out by David Hume, is the argument from design for the existence of a supernatural god (both because the universe is not meaningfully analogous to a machine, and because proponents of the argument typically refuse to draw the additional logical implications of an analogy between god and human designers, such as mortality, imperfection, etc.).

* Consilience: this is often referred to as “inference to the best explanation,” and it is essentially what scientists, as well as forensic investigators, do all the time (Sherlock Holmes, the Arthur Conan Doyle character, actually engaged in consilience, not deduction – contrary to what its author wrote). The idea is to examine as much relevant information as possible, and then draw the most likely (notice: not necessarily the truthful) conclusion compatible with the available data. Darwin’s theory of evolution is a masterful example of inference to the best explanation (despite perennial creationist nonsense), and he famously referred to it as “one long argument.”

Good, so now we don’t have any more excuses for sloppy thinking or writing, do we?

16 comments:

  1. Two questions:

    Is it more constuctive or sensible to study something like, for instance, Geometry by means of induction or deduction?

    Have a practical reason to ask that. I know it may obvious to "math" capable people, but it is not to me.

    secondly,

    When one is studying or drawing conclusions over evolution, on the other hand, which method are you most commonly using? And why?

    One gets the impression that Darwin started with the miniscule details of nature and formed a premise or conclusion based primarily off of that method. And it may be ONE LONG ARGUMENT, but it sure can ignore lot of overwhelming macro details that have much greater influence over reality than those little details do or ever could realistically have.

    This is not unlike observing where tea leaves happen to settle, don't you think? I mean the fact that they settle this way or that means something. BUT what it means has practically nothing to do with the tea leaves themselves. That's the essential problem with focusing on details only.


    happy christmas holidays, M and everyone.
    cal

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  2. cal,

    I think your tea leaf comparison is a prime example of "irrelavant analogy".

    There is no real evidence involved in reading tea leaves. Reading tea leaves is no different from astrology or palm reading. It involves a "mysterious" ritual after which one makes vauge refrences to a future that could apply to just about anyone.

    Evolution, on the other hand, is supported by a mountain of evidence that spans most scientific fields of study. Much of this evidence (for example, pseudogenes, vestigial body parts, dormant genes in humans that are active in apes) makes no sense out side of evolutionary theory.

    Now, if one chooses to interpret this evidence another way, fine. He/She can come up with a better theory that accounts for the evidence.

    But I hope they don't cry foul when the rest of us use false analogies in a dishonest attempt to discredit them.

    Noah

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  3. I DON'T BELIEVE in tea leaf reading! But that's the point about BEGINNING ONE'S PREMISE WITH details that are not governed by truths on more solid factual footing than themselves.

    The principles that essentially cause tea leaves to fall where they do have everything thing to do with chemistry and physics, and next to nothing to do with the leaves themselves AND NOTHING WHATSOEVER to do with paranormal properties.

    get it?


    "....is supported by a mountain of evidence that spans most scientific fields of study. Much of this evidence (for example, pseudogenes, vestigial body parts, dormant genes in humans that are active in apes) makes no sense out side of evolutionary theory."

    I swear, Noah, if you are able to take the proverbial 'tea leaves' and show me how they "cause" the "evidence that spans most scientific fields of study" - chemistry and physics , i.e. and make the aforementioned biological details fall where they do, you could change the whole world-view of millions of marginal, half-believing evolutionists! NOT to mention change the poor state of education for the whole United States and abroad!

    I mean, think of the implications of it all!


    In the end, the affirmation of a logical hierarchy in the development of ideas truly does matter, no matter how well one may thinks he thinks.

    c

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  4. Cal,

    "that's the point about BEGINNING ONE'S PREMISE WITH details that are not governed by truths on more solid factual footing than themselves."

    I find that soooo ironic coming from someone with your worldview and ideological position. It would be funny if I didn't know that you are dead serious about it.

    At any rate, in answer to you serious question, geometry is all a matter of deduction, as it is math, and more generally formal logic. Geometric axioms are given as starting points, then one deduces properties and consequences.

    Evolution, on the other hand, like any other scientific theory, is arrived at with a combination of deduction and induction. For example, it is an inductive generalization that living organisms tend to produce more offspring than can be supported by the environment. It is also an inductive conclusion that there is heritable variation for characters that contribute to survival and reproduction. From these two inductions (which one can use as premises) Darwin was able to deduce the necessity if natural selection.

    Oh, and how exactly does "God did it" account for the innumerable details that allegedly Darwin missed?

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  5. "I find that soooo ironic coming from someone with your worldview and ideological position. It would be funny if I didn't know that you are dead serious about it."

    Of course I am. What is more “true” than what is literally true about our inner self and motivations?

    Nothing is more important than that.

    Every idea, fact and observation has to filter its way past all of our spiritual /emotional baggage. (whether we like that fact or not) If our world-view about facts and truth isn't thoroughly honest, all data we come in contact with has the potential to be mishandled.

    The reason I asked the Q about Geometry, is that I had came across a textbook from Berkley which claims to take on Geometry by means of the inductive method. I’ve read through some of it, but before I'd pass the info on to someone else, I wanted to know.

    I'm in a big hurry, otherwise I'd take you to task on EVERY LAST THING! :)

    lucky you.
    c

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  6. The fear of the fact is the beginning of wisdom.

    ReplyDelete
  7. cal,

    You have just demonstrated yet another dishonest argument, namely, the Strawman Fallacy.

    I,In NO WAY suggested that you belive in tea laef reading. I simply stated that COMPARING EVOLUTIONARY THEORY TO TEA LEAF READING IS DISHONEST. And it is. And that is what you did. Period.

    But I will give you the benifit of the doubt and assume that you misunderstood my point, if someone else on this blog (other than you) can point out how my point suggests that I thought you BELIVED in tea leaf reading.

    Otherwise, I will assume that you are trying to distract the audiance of this blog from my point through dishonest means. (A common evolution denier tactic, as the case in Dover recently proved.)

    Noah

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  8. A P.S. To Massimo and Others,

    I realize that I have been a bit hostile lately. Normally, on most subjects, I pride myself on playing the middle ground. But I have become convinced that, for the most part, the Right Wing opinion on most of the issues we discuss here go from ignorant to down right willfully dishonest.

    Just how I see it.

    I would truly appreciate an opinion on whether or not I should scale back my rhetoric.

    And I apologise if I come off as offensive.

    Noah

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  9. "But I will give you the benifit of the doubt and assume that you misunderstood my point, if someone else on this blog (other than you) can point out how my point suggests that I thought you BELIVED in tea leaf reading."

    The following (below) is what I saw, and that was what it seemed to imply to me. Are you hurt because you thought I was talking down to you? That was not my intent. Just trying to make a clear point, that's all.

    "There is no real evidence involved in reading tea leaves. Reading tea leaves is no different from astrology or palm reading. It involves a "mysterious" ritual after which one makes vauge refrences to a future that could apply to just about anyone."


    Are you like depressed due to the holidays or something? It does happen to some people I understand. Possibly more so to philosophcal types and "fathers" shelling out money through out the season for "stuff". :)

    I'll gone after tomorrow morn. for a few weeks, so if I don't answer back soon, don't think I'm ignoring a comment of yours, Noah. I'll be able to read RS occasionally, but I make it a practice to stay away from e-mail and other internet distractions when I'm home with my dad.

    what ever is bothering you, very sorry for it.
    cal

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  10. Noah,

    as a matter of general policy, I'd like the blog to be about respectful conversation and intellectual engagement, rather than letting off steam or being down right offensive. I usually delete the latter types of comments, but letting off steam is something I occasionally do too, so I can't blame others.

    What I would like to see is more in depth discussions of broader topics than just abortion and the existence of God, which is why I try to vary the subject matter of the posts as much as my own readings make possible. So far, however, it has been fun!

    ReplyDelete
  11. Cal,

    Thanks for the concern, but I've actually just had the best holidy of my life, my first as a father. In terms of my personal life, I don't think I've ever been happier.
    The only things that seem to bother me these days deal with the nature of right wing politcs.

    Somtimes I wish I could be one of those people who just doesn't care. Alas, such is the curse of being born with a passionate disposition.

    In any case, I hope you enjoy your time with your father and look forward to future spats.

    Noah

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  12. I've been reading some of your articles on Rationally Speaking (the website).

    It seems quite clear to me that you need to continue your research on how to think before teaching others. I've noticed that many of your arguments are fraught with contradictions and ad hominem attacks. Neither of these advance your arguments against IDM. In fact they signal defeat in the argument.

    Professional standards of argumentation should be maintained at all times. Ad hominem attacks would not be tolerated (I hope) in a peer review process. Failure to maintain professionalism leads to the question, "What other presentations by this person are invalid?"

    Dan

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  13. I've noticed that many of your arguments are fraught with contradictions and ad hominem attacks.

    Any examples, so we can have an idea if YOU are not the one practicing "ad hominem" attacks, Dan?

    And, more important, can you point out what you think is wrong in the blog post about "deduction x induction" itself, and how and why previous texts by Massimo would invalidate the conclusions of the post? (remember to refrain from "ad hominem" attacks, if possible)

    J

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  14. Neither of these advance your arguments against IDM.

    Sorry, what is "IDM"?

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  15. Sorry, what is "IDM"?

    I struggled with that one for a while too, until I realized it had nothing to do with induction/ deduction. I guess IDM would be "inteligent design malevolence", or maybe "malady" or, technically, "myth". Although I suspect he meant "movement" (backwards, I'd say).

    J

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  16. Noah: "Thanks for the concern, but I've actually just had the best holidy of my life, my first as a father."

    Very good. And the sincerest congratulations on the birth of your first born.

    Make a strenuous effort to never believe a lot of what many people say about kids and teens in particular. (i.e. the "generation gap" myth and all that kinda stuff) My kids -15, 17, & 18 have been the most fun a person could ever have on this earth. REALLY. And especially in their teens.

    Try to make the more challenging, self-sacrificing choices now. Don't leave those things up to other people who could care less about your child. (the gov only cares about “the machine”. Even with all our flaws, mommy’s and daddy’s virtually always know best what turns a child into a great adult!) Hopefully, and my wish for you is that your kids will grow up to be individuals you'll love to be around, as I do mine.

    This is what I learned from my parents.


    "The only things that seem to bother me these days deal with the nature of right wing politcs."

    Our politics may very well be defined by what we each do when we don't get our way. If some philosophies can be "truer" than others, so can attitudes, I think.


    "In any case, I hope you enjoy your time with your father and look forward to future spats."

    Thank you. I have no intention of having “spats” with you, Noah. Only to exchange one set of ideas with you for possibly better ones.

    Time will tell.

    cal

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