Thursday, December 11, 2008

Fallacious Fallacies

In his book (mostly) on informal fallacies, Attacking Faulty Reasoning, T. Edward Damer uses (a caricature of) one particular pro-life argument as fodder to expose fallacious reasoning.

This example takes place in his section on "attacking the fallacy," where advice is given on how to attack fallacious arguments. One of his "attacks" is to employ the standard attack by counter-example. This method uses the same form of argumentation as the argument you're attacking while making sure to argue for an obviously absurd conclusion.

An example of refutation by logical counter-example would be:

  1. All religious adherents are irrational and self-deluded.
  2. John is irrational and self-deluded.
  3. Therefore, John is a religious adherent.

To easily see the fallacy, we just use the same form of argumentation, switch around some terms, and come to an obviously abusurd conclusion. Like this:

  1. 1. All dogs are mammals.
  2. 1. Flipper is a mammal.
  3. 1. Therefore, Flipper is a dog.

This is a very useful way to demonstrate bad arguments. In fact, it is used quite often on this blog when the logic of someone's argument is used to demonstrate the error of their ways. Frequently the conclusion reached by using their logic is attacked as if that is a substantive rejoinder. But the conclusions are not usually endorsed just like the conclusion that Flipper is a dog is not being endorsed. Some of those who frequent here need to keep that in mind.

Now, after explaining a useful way to deal with bad arguments, Damer uses as an example what he takes to be a somewhat popular pro-life argument. Damer names this the "fallacy of the continuum," and shows how it is made by the pro-lifer:

"Suppose that an opponent argued in the following manner: The fetus is a human
being at birth. Right? And it certainly did not suddenly become a human being at
delivery. In other words, it would be silly t say that the fetus is a human
being at birth and not a human being a minute earlier or an hour before that or
a day or a month before that. At no time would you be able to say rationally
that the fetus suddenly becomes a human being. So the fetus has to be just as
much a human being at conception as it is at delivery." (p.48-49)

Damer "demonstrates the faulty character of this kind of reasoning" by constructing this counter-example:

"An atmospheric temperature of 100 F is regarded hot. Right? And it certainly
did not suddenly become hot at 100 F. In other words, it would be silly to
insist that a temperature that is one degree, or five, or ten degrees less that
100 F is not hot. And at no time would you be able to say rationally that at
some particular point during a period in which the temperature moves from 0 F to
100 F that the temperature suddenly becomes hot, one could conclude that at 0 F
it is just as hot as it is at 100 F. " (p.49)

I think Damer is guilty of a straw man fallacy here. He is also guilty of violating one of his principles as to what constitutes a good argument - the rebuttal principle. Damer rightly claims that, "An argument is not a good one of it does not anticipate and effectively rebut, or successfully blunt the force of, criticisms of the argument and of the position that it supports" (p.30). And Damer is clearly making an argument. It can be expressed thus:
  1. 2. All arguments that commit the fallacy of continuum are poor arguments.
  2. 2. The no-difference-from-birth-to-conception pro-life argument commits this fallacy.
  3. 2. Therefore, this pro-life argument is a poor argument.

Before I register some concerns, I should point out that I am not objecting to the test by counter-example principle, nor am I objecting to the fallacy of continuum. The latter point means that we will accept premise 1.2. The structure is valid, and so if all the premises are true, the conclusion goes through.

Now, in one sense Damer's conclusion does go through, but that's only because the pro-life argument that he's trying to represent isn't properly stated. And it would be charitable to assume that Damer wants to attack proper representations of arguments. Having qualified, we need to object to a premise so that the conclusion doesn't go through. The only one left to reject is premise 2.2. And so that's what we'll do.

I propose to challenge 2.2 in three ways: (i) A brief, correct statement of the pro-life argument being addressed; (ii) relevant disanalogies between the pro-life argument and the pro-heat counter-argument; and (iii) some possible objections.

A Brief, Correct Statement of the Pro-Life Argument

"Given the facts of embryology and fetal development, at conception, a whole human being, with its own genome, comes into existence, needing only food, water, shelter, and oxygen, and a congenial environment in which to interact, to grow and develop itself to maturity in accordance with her own intrinsically ordered nature. Like the infant, the child, and the adolescent, the conceptus is a being who is in the process of unfolding its potential, that is, the potential to grow and develop itself but not to change what it is. This being, because of its nature, is actively disposed to develop into a mature version of herself, though never ceasing to be herself. Thus, the same human being that begins as a zygote continues to exist to its birth and through its adulthood unless disease or violence stops it from doing so. For there is no decisive break in this physical organism's continuous development from conception until death from which one can infer that the being undergoes a substantial change and literally ceases to exist and a new being comes into existence (like the substantial change that the sperm and ovum undergo when they cease to exist and a new being comes into existence). This is why it makes perfect sense for any one of us to say, "When I was conceived..." (Beckwith, Defending Life, Cambridge, 2007, pp. 72-73).

It is evident that this is the type of argument Damer intended to attack in his example. It is obviously stronger than Damer let on. Once stated, the flaws in Damer's counter-example should be self-evident. But, we will make a few explicit.

Relevant Disanalogies Between the Pro-life Argument and the Pro-heat Counter-argument

a) It is obvious the pro-life argument is talking about essential features that obtain in all possible worlds. In all possible worlds, a human being is, say, made in the image of God. Any world where S is human, S is made in the image of God. If S is not an image bearer of God at W1, then S is not human at W1. We can substitute something like "rational animal" for "image bearer" if you insist. But, with "regarding something as hot," this is not the case. For beings that have lived their whole life on Mercury, 100 F is regarded very cold. For beings that have lived their whole life on Neptune, 0 F is regarded very hot. This applies to humans to a lesser degree. So, with respect to qualia, 0 F can be "just as hot" to some being S as 100 F is to S*. This seems to be Damer's understanding with the use of the word "regard." But pro-lifers don't just "regard" a fetus as human. That's the only way 100 F is "regarded" as hot.

b) Putting aside the subjective elements of the counter-example, the language is misleading. Temperature is a number that is related to the average kinetic energy of the molecules of a substance. Heat is a measurement of the total energy in a substance, both kinetic and potential. All this means is that temperature of 100 F implies a certain amount of kinetic energy. It doesn't have this energy when it is one, five, or ten degrees cooler. It may be regarded as hot, but it certainly did "suddenly" possess the amount of kinetic energy at 100 F that it did not have at 90 F. Thus one could "rationally say" that at some particular point the object had more kinetic energy than it previously did. Damer's counter-example hinges upon equivocations. Between subjective "regardings" and objective "measurements" of energy. This is why steaks objectively "keep" in the freezer and not in the hot sun. Something kept "hot" doesn't freeze. What are the relevant differences between the various stages from conception to birth to infancy to adolescence, then? Is it just that one has "more" of something that the other? The pro-life argument claims that there is no relevant point where the fetus "becomes" human. The pro-life position clearly doesn't believe that "more" of something makes for humanness.

c) So, understood as qualia, the argument proves too much. There is no essential, fixed characteristic that can demarcate human from non-human, thus racist laws that concluded that blacks were 2/3 human were not in error. Understood as objective, the argument proves too much. For I can point demonstrate that 0 F is not "just as hot" as 100 F. But where is this relevant difference between the birthed human and the human 1 minute before and 1 month before, etc.? So the objective "heat" argument tells us that we can point out when something has more internal kinetic energy than something else. But if this is how we demonstrate who is and who isn't human - by who has "more" of some quality - then we're right back at blacks as 2/3 human!

Some Possible Objections

Damer may claim that his counter works just fine because there is no relevant difference between when something is regarded as hot and cold. But considered subjectively, this is false. People can clearly regard when something is not hot anymore. To claim that they cannot pin point exactly when this is, is pedantic and commits the "beard fallacy." Considered objectively, this is false because all we need to do is look at the amount of internal energy. I argued that both views are disanalogous with the pro-life argument. Pro-lifers do not merely "regard" something as human based on subjective qualia, and they do not count something as human based on it have "more" stuff than other things. If so, they would logically claim that infants are "less" human than adults.

The pro-life argument asks what relevant or non-arbitrary difference can be pointed to that shows that the conception of two human parents' gametes is not human while it is human three, six, or nine months down the road. A handy acronym developed by pro-lifers to demonstrate this has been called the SLED test:

Size: Is it that one is bigger than the other, then are infants "less" human than adults?

Level of development: Is it that one is "more" developed than the other, then are down syndrome kids "less" human than geniuses?

Environment: Is it your environment? One is located "outside" the womb while the other is located "inside?" Then when people are located in Africa, may we take them as slaves? Is location a "relevant, non-arbitrary" distinction?

Degree of Dependency: Is it that the 12 week old fetus is more dependant upon the mother than the newborn? Is the preemie in the NICU "less" human than the healthy one down the hall, then?


So it would appear that Damer's counter is totally disanalogous to the pro-life argument he wants to critique. There are relevant differences between when something has more internal energy than something else. But this is disanalogous to how pro-lifers understand human and non-human, i.e., it's not that one has "more stuff" than the other. Even considered subjectively, humans can easily "regard" something as hot or cold. But beyond that, "regarding" is subjective and thus not a "relevant, non-arbitrary" difference, which is what the pro-life argument asks for when claiming that x is not human but y "suddenly" becomes human. So I conclude that Damer's example of a fallacy is fallacious.


  1. Well, I know one book not to buy for home schooling my kids in critical thinking.

    I call a category mistake. Damer confuses (temporally changing) stage of development with (unchanging) essential nature.

  2. The category error is what I initially saw, too. The real question would not be, when does a temperature become hot? but rather, what makes a temperature a measure of heat energy in the first place?

    But then, I enjoyed the further lesson in argumentation. Quite instructive. Thank you.

    Geek alert: beings on Neptune would consider 0 degrees "warm" not "cold," or, at least, all the ones I know would.

  3. Any recommendations on good books to read on logic and critical thinking?

  4. Good post, Paul. Just a heads up--The SLED test is used by pro-lifers--not pro-choicers--to show there is no essential difference between fetus and newborn (or adult) that would justify killing you at the earlier stage of development.

    Nevertheless, awesome job!

  5. Thanks, I fixed those blunders.

    Sean, Copi & Cohen's is a stand-by. In the 12th ed. now. It discusses formal logic more, though.

    Engel has a very good, user friendly, *introduction* to informal fallacies in With Good Reason.

    Douglas Walton has a more advanced book on informal fallacies in Informal Logic.

  6. Turns out I have the first two books in my library, just need to read them (they're next on my list now). Except I have the 8th edition of the first book, not the 12th. Bummer. Third book now on my to buy list.

  7. Sean, 8th edition is fine. I have the 9th. I also know a lot of the college logic profs are now using Hurley's Intro to Logic. But Copi's works just as good.

  8. Is this the book?

    Looks like it's up to 13 editions!

  9. Yes, that's right, I forget they put out a new edition recently.

  10. Paul: For beings that have lived their whole life on Mercury, 100 F is regarded very cold. For beings that have lived their whole life on Neptune, 0 F is regarded very hot.

    Vytautas: I object this is a possible world. You are allowing for physical conditions that would be hazardous to humans. How can a human live on Mercury or Nepture?

  11. Vytautus,

    i) note that I said "being." A "being" doesn't have to be a "human" being.

    ii) Possible worlds talk usually looks at *logical* possiblity. It may be *physically* impossible now, for *human* beings to live on Mercury or Neptune, but that doesn't mean it is impossible in the broader sense. For example, for all I know, our glorified bodies may be able to live in Mercury or Neptune. So, it is still a *possible* world, even for humans. The *physicality* of humans would just need to be constructed differently. But physical possibility or impossibility doesn't affect possible worlds talk.

  12. For that matter, Paul could also change it to say:

    In the summer, 40 degrees is cold; in the winter, 40 degrees is warm.


    For an Eskimo, 100 degrees is extremely hot. For an Arab, 0 degrees is extremly cold. (BTW, I should point out that my family being from Alaska, my parents told me how they'd attend college courses and in the morning it would be -60F. When they left in the afternoon, it would be -20F, and they'd take off their coats because it was 40 degrees warmer.)