The Dennett Tennis Test

This is a simple little tactic to consider employing next time you find yourself in conversation with somebody who doubts the efficacy of scientific method, particularly anybody who wants to propose any kind of alternative.

You know the sort, I’m sure. The kind of person who says “sure, scientific data argues that acupuncture is total and utter garbage, but maybe acupuncture is one of those things science isn’t equipped to investigate.” Or the kind of person who says “absolutely, you’re right, I have no evidence that my god exists, but frankly I’m offended at your crass insistence that everything has to come down to evidence.” Or “how ridiculous to suggest that science has anything to say about the supernatural.”

“Oh, you’re so reductionistic,” another might say, shaking their head with earnest sympathy, “there is so much more to mother nature than your sterile lab experiments.” (Yes there is, evidently, but what exactly is your point?)

Or nodding with diplomatic wisdom, one will say, “yes, yes, I see your point, but don’t you think your scientific paradigm is just a social construct, one of many equally valid points of view?”

To all such people, I propose the following reply, paraphrasing philosopher Daniel Dennett:

You know what, your argument is completely convincing, except for one detail: everything you say proves unambiguously that you are a ham sandwich, wrapped in tin foil.

This is what I'm calling the Dennett Tennis Test (DTT). I’ll leave it to you to decide if the phrase is ugly or poetic. Faced with DTT, your conversation partner has 2 options:

(1) They can agree with you, at which point it is clearly time to end the conversation - they have declared themself to be mad.

(2) They can protest that your conclusion is unsupportable, thus proving that they are dishonest - they do not really believe in the efficacy of their own argument.

So how does this work, and where the hell does the weird name come from?

The thing about tennis is that, quite like the two options listed above, there are 2 ways you can play the game: with or without the net. To make the game fair, though, if one player plays with a net, then so does the other.

I picked the phrase ‘Dennett Tennis Test’ in honour of an argument made by Dan Dennett, (in his excellent book “Darwin’s dangerous idea”) which he built around a remark that he attributes to Ronald de Sousa, likening philosophical theology to intellectual tennis without the net. Just as the tennis net filters out bad serves and bad returns, so in a reasonable discussion does rationality filter out the crummy arguments. The point of DTT is to say “oh, I didn’t know you wanted to play without the net, well, never mind, I’m a sportsman, I’ll play the way you want.” If your opponent agrees to this arrangement, and its most explicitly displayed outrageous consequences, then they signal that they have no commitment to approaching the truth. If they protest, then you have the right to ask why they expect the rules to apply asymmetrically. Either logic is abandoned, allowing their arguments and yours to pass unfiltered, or reason steps in, exerting the same selection pressure on everybody’s statements. When your opponent protests that your conclusion is unjustifiable, they establish exactly the standard of evidence that is sufficient for their own position to instantly crumble. 

All the arguments I have taken as examples at the top (these are not straw men of my own concoction, they occur regularly, even within academia) take the form of asserting that there is a way of knowing that bypasses the need for evidence and its logical evaluation. The alternative-medicine advocate who sees the scientific research, but still clings to the belief that the hocus-pocus treatment works is claiming access to knowledge that science can’t deliver. They’re not just saying the science was done badly, but that science is the wrong tool entirely. For example, Dr. Peter Fisher, homeopath to Queen Elizabeth II and prominent homeopathy researcher, (here reaching a stunning level of perversity): "'Inherent implausibility' is a poor guide to future understanding."

The religious enthusiast, clinging to the notion of faith as an alternative to reason, decides to believe, as if that mere decision were enough to shape the structure of reality - as if wanting to have faith is enough to make it true. Many religious believers actively boast of their non-reliance on evidence, claiming it virtuous to place their faith in … well in faith itself actually. But by this "logic", I can just as legitimately put my faith in absolutely any bloody thing I please. In reality, the blatant circularity of this kind of epistemology cannot convince any honest thinker. It is really just an obfuscation, where somebody really wants a thing to be true (or wants others to believe it), but knows deep down that the evidence they have is insufficient. With a complex enough wording, repeated sufficiently often, the believer hides the fact that their belief really is based on evidence - mainly testimony from trusted people (have you noticed how different belief systems exhibit clear spatio-temporal correlation? Is it coincidence that most religious people follow the same religion as their parents?). Such evidence that people have for their religious faith, however, crumbles when subjected to the tiniest scrutiny, (for example, exactly similar evidence provides exactly as reliable support for a host of other contradictory hypotheses) and they invent this capability to know without evidence, which they call faith, in a desperate attempt to avoid the obvious, uncomfortable conclusion. Logic is suspended, without any justification whatsoever - ham sandwiches, all round.

In 1996 physicist Alan Sokal wrote a preposterous spoof paper¹, which he submitted to a ‘serious’ philosophical journal, ‘Social Text’. The paper was crammed with utter nonsense statements (and copious flattering references to the works of the journal’s editors), and they loved it. They published it, never once suspecting that it was a load of deliberate trash. The subject of the paper? That science is a social construct, that all belief systems are equally valid, and that quantum theory proves it. The academic (nominal) philosophers behind the movement this journal epitomizes were committed to the view that if I believe that I can step out of a 10th floor window and float away to Jupiter to enjoy cups of Jovian tea with the locals, before returning home to commune holistically with all the insects on the planet, obtaining crucial knowledge about the birth of time from them, then that belief is as valid as the belief that the world is approximately spherical. This is a philosophy that explicitly refuses to rank the believability of propositions based on the observed behaviour of reality - a form of radical skepticism in which logic is eagerly shunned. How have these people managed to create an academic discipline based on the deliberate application of no intellectual discipline? How would they respond to DTT? Sokal has effectively tried it, and they went for option (1).

In case you think my characterization of the views of the 'strong sociologists' and postmodern relativists - the sorts of academics that Sokal was ridiculing - is far too absurd to be accurate, Sokal's book, written with Jean Bricmont, "Fashionable nonsense," (also published as "Intellectual Impostures") is crammed with quotations from people at the forefront of this movement that again and again prove exactly this. Here are two brief examples: 

Barnes and Bloor²: 

"It is those who ... grant certain forms of knowledge privileged status, who pose the real threat to a scientific understanding of knowledge and cognition."

Paul Feyerabend³: 

"All methodologies have their limitations and the only 'rule' that survives is 'anything goes'."

The proposition that the person you are arguing with is a ham sandwich may be good for raising a cheap laugh, but one might feel that it's far too ridiculous to serve as a serious parody of anybody's actual views. Under close examination, though, it doesn't take long to see that the arguments that I propose to target with the Dennett Tennis Test propose a system of belief formation according to which this proposition is every bit as valid as those that being argued for - gods, the healing power of crystals, truth as a social construct, or whatever it happens to be.    

---

References

[1]	Alan Sokal, 'Transgressing the boundaries: toward a transformative hermeneutics of quantum gravity', Social Text #46/47, pages 217 to 252, 1996
[2]	'Relativism, rationalism, and the sociology of knowledge', in 'Rationality and relativism', edited by Hollis and Lukes.
[3]	'Against method,' Paul Feyerabend, 1975