Sunday, January 22, 2012

The Debate: Newt Gingrich vs. Jack Horner

This is something I had completely missed until my wife found it linked to on a political blog a few weeks ago. Filmed in 1998, it's a pretty awesome hour-long video of a debate held between paleontologist Jack Horner and then-Speaker of the House Newt Gingrich. The topic: "Were Tyrannosaurus rex active hunters or pure scavengers?" What else?

The debate is actually a follow-up to a previous forum Gingrich did with Horner, both as fundraisers for the Museum of the Rockies. Gingrich, it seems, is an avid armchair paleontologist.

It looks like C-SPAN doesn't let you embed videos, so here's a link to the full debate:

What's fascinating about this debate is how it illustrates almost point-by-point a lot of issues I've seen cropping up online lately about the nature of scientific hypotheses, and in particular Horner's approach to them. As some of you may know, Horner recently backpedaled on the whole tyrannosaurs-as-pure-scavengers hypothesis, saying that, from the start, it was merely an attempt to illustrate how the scientific process is supposed to work as opposed to how it often goes in paleo. (Horner explicitly renounced the pure scavenger theory in, among other places, an October 2009 interview on the outstanding Skeptics Guide to the Universe podcast).

Watching this debate unfold, two things surprised me more than I thought they would. First, wow, Gingrich really did his research for this! He comes fully prepared with several examples and analogues to modern ecosystems, many of the same arguments I've seen used in forum debates on this topic, including the fact that there are few if any pure scavengers among modern animals, that hyenas will often take live prey, that vultures can get away with it due to their ability to fly over enormous areas in search of carcasses, etc. Newt knows his stuff, and handily pummels Jack in the debate (though Horner appears to be acting as sort of a gracious host, lobbing him a lot of softballs and overall "letting" Gingrich win.)

The second thing, though, is in Horner's closing arguments. Gingrich easily beats Horner by throwing out analogy after analogy, employing simple logic to demonstrate why his hypothesis "T. rex were not pure scavengers" is superior. But Horner points out, in a way, that it doesn't matter. Debates are antithetical to science. Empirical science is in no way about who has the better argument. It's about who has a more rigorous, testable and ultimately falsifiable hypothesis and can support it with more data, not better analogies.

I have been a T. rex as predators booster since I was 6. But after watching this debate, it is clear to me that Horner has always had a better, more scientific hypothesis and overall approach to the science of paleontology. He is correct that the default assumption has always been that T. rex were active hunters. But at the end of the day, assumptions are not science, and it's a little bit appalling that this assumption has been made an implicit basis of so many statement published in peer-reviewed scientific papers without question. You can never, ever disprove the hypothesis that T. rex were active hunters without a time machine, because it's logically impossible to prove a negative. That's why in science, if we have a positive statement as our hypothesis, it's often necessary to take the null hypothesis (the opposite statement to the one we are testing) and attempt to disprove that in an attempt to support the actual hypothesis. Like string theory, T. rex-as-hunters is an idea that makes logical sense on paper but is unfalsifiable, and therefore not science--just educated speculation.

However, Horner's hypothesis can and has been disproved. We now have evidence of healed-over T. rex bite wounds that show that at least occasionally, they bit living prey species. Does this prove T. rex were active hunters? Not necessarily, but it's a major piece of data against Horner's scavenging hypothesis, and that is actually the strength of Horner's position--that it can be tested and shown to be wrong. In science, it's not always better to be right than it is to be rigorous.

So while he may have won the debate, Gingrich was right for the wrong reasons, while his opponent Horner was wrong for the right reasons.


  1. Interesting episode.
    I a bit dislike those using the (often misunderstood) concept of "falsification" as a phylosophical justification of their false idea. Is paleontology a phylosopy or a science?
    Creationists and BANDists often cite falsificationism as a weapon against what they are unable to fight with the evidence.
    And I hope we all stop talking about that hypothesis as like it was one of the most important problem in paleontology (as it seems looking at how often it's mentioned in every media). Why nobody discuss the hypothesis that Carnotaurus was only scavenger? Or Giganotosaurus, or Spinosaurus, or Dilophosaurus, or Smilodon, or Anomalocaris, or Homo neandertalensis?
    If that hypothesis is more scientific than its opponent just because it's can be falsified, why do paleontologists don't use it for every animal?

  2. I don't think that's the right way to look at it. We shouldn't assume each individual carnivore is an obligate scavenger until that hypothesis is disproved, but we should also not assume the opposite. No assumptions of any kind should be making their way into the scientific literature if it's going to alter the results.

    1. Mickey give below most of my answer.
      I have never assumed such bizarre estreme positions as "only scavenger" vs "killer-machine" like those who have seen as such these controversies. I don't want to reduce the paleontology to a physic-mimic Popperian world where falsification is the only discriminant between scientific hypothesis and unscientific ones. Is falsification the good method for paleontology? Popper himself said evolution cannot be falsified? That means evolution is not scientific? No, it means evolution is both a physic (Popperian) and storic (not-Popperian) science. Paleontology probably follows the same topic.
      If the "falsification" model suggested for the ecology of Tyrannosaurus is the normal way paleontologists analyze fossil ecology, we should see its application more broadly in the field. Why it does not happen? Is Horner the only intelligent paleontologist around? He is a smart man (I've had the honor to meet him) but I don't think the rest of the paleontological community is blind in front of the way to look at dinosaur ecology.

  3. I agree with Andrea. Also, the idea you can't 'prove' a negative in science is flawed, as Richard Carrier explains here- . Indeed, paleontology is full of unprovable beliefs that are nonetheless justified until sufficient counterevidence is provided, and "all large terrestrial carnivores don't depend primarily on scavenging" is one of them. The alternative is throwing out entire fields like phylogenetics because they're based on assumptions that haven't been demonstrated to be true in every case.

    And here I thought the most substantive thing I'd be saying in reply was some joke about me agreeing with Newt. ;)

  4. To go along with this, I'd say that Honer's hypothesis regarding T. rex, now having been falsified, would by extension falsify the null hypothesis for all large theropods, due to the fact that Horner identified so many unique supposedly "obligate scavenger" characters that are now known to be present in an active predator. If T. rex was Horner's best example of a scavenging theropod, and we know it also took live prey, then all other known theropods, which are less well adapted to any hypothetical scavenging lifestyle, should also be assumed active predators. I'm not arguing we should not allow for parsimony, only that the initial assumption needs to be backed up with evidence, and then parsimony can be built from there, sort of like phylogenetic bracketing.

  5. One thing to keep in mind: very often, *negatives* can be expressed as positives. And I just see that Mickey has provided a link for this - tx!

    What really makes me slide off my chair in frustration is how someone so obviously CAPABLE of using logic and sound reasoning as The Newt has apparently either lost his vertebral column or suffers from telencephalic death! :eek:

  6. I read on Facebook that it was Holtz who supplied Gingrich with the relevant info, so that explains something.

  7. "Proving a negative"
    Falisification, afaik, has nothing to do with not being able to prove a negative. Popper realized that Positivism Logical Empiricism was going nowhere and that inductively 'confirming' a position wasn't what science was really about. Therefore he promoted falisificationism and versimilitude (which Stephen Colbert calls "truthiness", in a way).

    "Honer's hypothesis regarding T. rex, now having been falsified"
    But it hasn't been falsified. We have some counters to what we expect, but the thesis can be protected by modifications to our auxiliary assumptions. Its not 'simple' one-shot falsification that Popper and his student Lakatos were after. The Scavenger thesis requires, in light of evidence like tooth marks, changes in auxiliary assumptions about T. rex, which is acceptable. The question is, what do those modifications do to the whole Scavneger research program? Do they just try to brush away counter-evidence after counter-evidence, and thus the program degenerates, or do they lead to new, successful interpretations of collected observations, which would be quite positive.

    "so obviously CAPABLE of using logic and sound reasoning as The Newt"
    What you have here is a demonstration that he is quite good a /rhetoric/. This is what nearly all politics used to be based on, in fact I dare say Gingrich considers himself a new Cato or some such, a skillful rhetorician who comes to power through debate.
    I guess that would make Obama a Gracchi, Santorum a Phyrrus, Perry a (wanna-be) Pompey, and some would paint Ron Paul as a Cataline.
    Woo Hoo, Ancient Romans and Dinosaurs in the same comment for the Win!

  8. "As some of you may know, Horner recently backpedaled on the whole tyrannosaurs-as-pure-scavengers hypothesis, saying that, from the start, it was merely an attempt to illustrate how the scientific process is supposed to work as opposed to how it often goes in paleo. (Horner explicitly renounced the pure scavenger theory in, among other places, an October 2009 interview on the outstanding Skeptics Guide to the Universe podcast)."

    My problem w/"the pure scavenger" hypothesis was that Horner continued to push it even after it had been falsified. Specifically, he said that there's "none whatsoever" (in reference to "evidence for hunting": ) despite the existence of Carpenter 1998 ( ).

  9. Yes, back in the late 1990s some people from Gingrich's staff called me up to ask for pointers about the issue. I can't say that I was the sole source of information, but I was certainly one source.

    Newt himself called me up on his way out to this debate (at least I assume it was this one: I don't know if he did this with Jack more than once): however, I left him on the line talking to my answering machine because I was on the other line with Jacques Gauthier discussing the forthcoming Ostrom Symposium.

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  11. Had not this interview lurked for over one decade quite a few endless debates could have been milden. I have, as we all, read quite a few offensive remarks at Horner due to this hypothesis of his.