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Syllogisms and ceasing to think

Chesterton’s superb short study St. Thomas Aquinas: The Dumb Ox contains, among countless delights of reasoning and composition, a brilliant little discourse on Aristotelian induction compared to the modern reductionism that masquerades as an enthusiasm for induction. Its utility in dismantling that hectoring bluster, everywhere in evidence these days, which goes around with grandiose gestures toward certain collections of empirical data, in order to pronounce an important debate OVER, will be readily apparent.

I have never understood why there is supposed to be something crabbed or antique about a syllogism; still less can I understand what anybody means by talking as if induction had somehow taken the place of deduction. The whole point of deduction is that true premises produce a true conclusion. What is called induction seems simply to mean collecting a larger number of true premises, or perhaps, in some physical matters, taking rather more trouble to see that they are true. It may be a fact that a modern man can get more out of a great many premises, concerning microbes or asteroids, than a medieval man could get out of a very few premises about salamanders and unicorns. But the process of deduction from the data is the same for the modern mind as for the medieval mind; and what is pompously called induction is simply collecting more of the data. And Aristotle or Aquinas, or anybody in his five wits, would of course agree that the conclusion could only be true if the premises were true; and that the more true premises there were the better. It was the misfortune of medieval culture that there were not enough true premises, owing to the rather ruder conditions of travel or experiment. But however perfect were the conditions of travel or experiment, they could only produce premises; it would still be necessary to deduce conclusions. But many modern people talk as if what they call induction were some magic way of reaching a conclusion, without using any of those horrid old syllogisms. But induction does not lead us to a conclusion. Induction only leads us to a deduction. Unless the last three syllogistic steps are all right, the conclusion is all wrong. Thus, the great nineteenth century men of science, whom I was brought up to revere (“accepting the conclusions of science,” it was always called), went out and closely inspected the air and the earth, the chemicals and the gases, doubtless more closely than Aristotle or Aquinas, and then came back and embodied their final conclusion in a syllogism. “All matter is made of microscopic little knobs which are indivisible. My body is made of matter. Therefore my body is made of microscopic little knobs which are indivisible.” They were not wrong in the form of their reasoning; because it is the only way to reason. In this world there is nothing except a syllogism – and a fallacy. But of course these modern men knew, as the medieval men knew, that their conclusions would not be true unless their premises were true. And that is where the trouble began. For the men of science, or their sons and nephews, went out and took another look at the knobby nature of matter; and were surprised to find that it was not knobby at all. So they came back and completed the process with their syllogism. “All matter is made of whirling protons and electrons. My body is made of matter. Therefore my body is made of whirling protons and electrons.” And that again is a good syllogism; though they may have to look at matter once or twice more, before we know whether it is a true premise and a true conclusion. But in the final process of truth there is nothing else except a good syllogism. The only other thing is a bad syllogism; as in the familiar fashionable shape: “All matter is made of protons and electrons. I should very much like to think that mind is much the same as matter. So I will announce through the microphone or the megaphone that my mind is made of protons and electrons.” But that is not induction; it is only a very bad blunder in deduction. That is not another or new way of thinking; it is only ceasing to think.

What is really meant, and what is much more reasonable, is that the old syllogists sometimes set out the syllogism at length; and certainly that is not always necessary. A man can run down the three steps much more quickly than that; but a man cannot run down the three steps if they are not there. If he does, he will break his neck, as if he walked out of a fourth-story window. The truth about this false antithesis of induction and deduction is simply this; that as premises or data accumulated, the emphasis and detail was shifted to them, from the final deduction to which they lead. But they did lead to a final deduction; or else they led to nothing. The logician had so much to say about electrons or microbes that he dwelt most on these data and shortened or assumed his ultimate syllogism. But if he reasoned rightly, however rapidly, he reasoned syllogistically.

Nowhere is this lesson more wanting than the disputation over climate change. Not a day goes by where some mandarin or professor or politician fails to ensnare himself (and attempt to ensnare the rest of us) in the blunder laid out by Chesterton: piling up impressive data to form premises, but declining to demonstrate via syllogism the conclusion he assumes. It’s much more convenient and self-satisfying to mount a soapbox and cut loose with a sanctimonious harangue.

Comments (16)

It may be graver today than Chesterton described. Bad enough is it to ignore the rational and logical prerequisites for engaging in the natural sciences, worse yet is it to also fail to understand the evidence within the sciences themselves. The modern liberal is comfortable to proclaim "science says" as enough evidence for the truth of his beliefs even when confronted with arguments demonstrating the opposite. What matters is that he has psychologically comfortable grounds for his belief ("other elite, intelligent people believe what I do"); not that the evidence is so voluminous, logic so impeccable, and argument so compelling that it moves him to accept the conclusion regardless of what others think. He hardly attempts to defend his believes on any ground higher than the authority of the university biology department; in this regard he displays less critical thinking than medieval peasants.

I agree with GW. Many of the claims made in the name of science are simply _not supported_ by scientific evidence itself. So they get propped up by loud yelling, by demonizing one's opponents, and by getting people fired. There is also an odd tendency to pretend that the burden of proof doesn't exist. In the case of AGW, in 2014 those advocating it treat it like an a priori default position! As though one could have deduced it from first principles or something and the burden of proof is on those who disbelieve it to show that it _definitely isn't true_. This is so crazy empirically that it leaves one almost gasping. AGW is a strong, substantive position that has nothing going for it intuitively. _If_ it is true, we can know that only by evidence, and if that evidence is to support draconian measures it must meet a very high threshold. The burden of proof is on the AGW advocates, especially those pressing for policy, _not_ on the skeptics. This should be obvious on its face, but for some reason it isn't.

As for what Chesterton says about syllogisms, I'm afraid I have to demur a bit as a philosopher, because taken literally what he says is incorrect. There are indeed distinctive _forms_ of reasoning that are non-syllogistic and non-deductive. Straight induction is one and so is explanatory reasoning. Contra Chesterton's statements here, these are not merely ways of gathering evidence for the premises of a final deductive syllogism that must be carried out. That is not, for example, how one is justified in believing that the sun will rise tomorrow. Nor is it how one is justified in believing, say, that measles is caused by a virus. (The first being a plain induction and the second an explanatory inference.)

On the broader issue, though, of whether the most vaunting claims made today (and perhaps in Chesterton's day too) in the name of Science rest on flimsy evidence and non sequiturs, I couldn't agree more.

Why do you bring climate change into a discussion about the validity of the syllogism? That the global temperature is rising, and the Arctic icecap is melting much more rapidly than can be explained by natural variability are empirical observations, as is the physics of greenhouse gases. As Christians, we are doing ourselves a disfavour by criticising the science on this issue. Proper stewardship of natural resources is a perfectly valid Christian position. Naturally there is the issue of balance of probabilities, but on this particular issue uncertainty is not our friend.


You say, "That the global temperature is rising, and the Arctic icecap is melting much more rapidly than can be explained by natural variability are empirical observations, as is the physics of greenhouse gases."

First of all, you know that the global temperature has not been rising for the past 16+ years:


Professor Curry also notes on her blog that while Artic ice is melting, it is unclear to what extent this is a result of anthropogenic greenhouse gases:


She also notes that sea ice has been increasing in the Antarctic:


So actually, as Christians, we should remain skeptical of the "science" of this issue and listen to smart critics of the climate 'consensus' and those who are willing to wade through IPCC reports and do the cost/benefit analysis for us:


Science and technology are indeed our friends...

Why do you bring climate change into a discussion about the validity of the syllogism?

Because, Dan Zachariah, there is a very common imposture at work in the world involving this matter. It often takes the form of pointing to various plausible sets of empirical facts regard temperature, polar ice, sea levels, etc; and then leaping to some drastic conclusions about needful policies of carbon emission reduction. Bill McKibbon and J. S. Kuntsler are two notorious dealers in these impostures.

I've written a greater length about this before:



Yes, I am fully aware of the various controversies around the issues of climate change. I also read Dr Curry's and Bishop Hill's blog regularly. Much of what passes for science in those blogs is a misrepresentation of statistics. Dr Curry's emphasis on uncertainty (which there certainly is) cuts both ways, just as there are two limits to a standard deviation. Climate does not change without a reason, or forcing - to put it technically.

Science develops through the postulation of a hypothesis, followed by a demonstration of the validity of the hypothesis. AGW is at the stage of a hypothesis, which needs demonstration by empirical data. Dr Curry has postulated no hypothesis, apart from invoking uncertainty, why the Arctic ice has melted so much, or why the Arctic temperatures are rising so much more quickly than the rest of the globe. That the Antarctic ice levels are increasing is explained by the fact that the Antarctic is largely landmass over which the ice is indeed melting rapidly. The resulting runoff of freshwater lowers the salinity of the surrounding seawater which causes the progressive growth of winter sea ice. This is an expected result of the physical chemistry of water. Also, there is no pause. Temperatures in the past decade have been higher than any other previous decade as the Berkeley dataset has shown.

In any case, the road to changing our dependence on fossil fuels is not particularly difficult, and is a very worthwhile goal. Driving small cars that are more fuel efficient and making buildings more energy efficient, encouraging frugality and economy and eschewing excessive consumption are Christian virtues. We want to encourage large families all over the world, so we also have a responsibility to ensure that every member grows up with these virtues firmly set in. Lydia, Elon Musk has shown that private enterprise can be very good in developing efficient engineering. The market has noticed this, too.


You are tedious.

I will acknowledge that the Berkeley dataset, which Dr. Curry is a big fan of, suggests the pause in warming (yes, there is a pause) is more slight than I thought at first (but dramatic compared to what the climate models were predicting):


And to blithely claim that "changing our dependence on fossil fuels is not particularly difficult" suggests you have no idea how a modern economy is run. Here is an organization that does:


Dan Z., when the free market *on its own* creates non-fossil means of fuel and power *because they are desired by real, individual people and are efficient and marketable*, not because the government has distorted the market by additional rules to "reduce global warming" and the market is then doing the best it can to work within those strictures, I will pay attention. Until then, I'm not holding my breath.

In any event, the idea that the actual policies proposed by AGW advocates are nothing more than mild and reasonable things that everyone should be doing anyway, merely a matter of being personally more frugal, that they would have no severe and negative economic effects on both the developed and developing world, is so breathtakingly incorrect that it scarcely merits an answer. Perhaps some of my blog colleagues can muster the energy to refute so egregious an implication, but not I.

In any case, the road to changing our dependence on fossil fuels is not particularly difficult

That really is an extraordinary statement. I sort of blew through it initially. I'm sure Dan Z. is aware that a good chunk of recent reductions in US emissions is a direct result of our recession and tepid recovery. But I'm also sure that he is aware that US and Canadian oil and gas decisively exceeds Saudi, Russian and Venezuelan oil and gas, not merely on economic efficiency, but also in cleanliness. In other words, replace a unit of oil from Russia/Gulf/Venezuelan production with a unit of oil from Canadian/US production, and you've both prospered North Americans and reduced global carbon emissions.

There are other options available as well: http://www.thenewatlantis.com/publications/why-and-how-we-should-break-opec-now

The main point here is that this declaration -- "changing our dependence on fossil fuels is not particularly difficult, and is a very worthwhile goal" -- amounts to two very dubious propositions which are not supported by the best available evidence. Normally, what they are supported by is bullying and impostures.

To put a stop to the nonsense:

That the global temperature is rising, and the Arctic icecap is melting much more rapidly than can be explained by natural variability are empirical observations,...

"Global temperature is rising" is a highly complex claim, subject to lots of needed qualifiers - over what time frame(s), taking into account or ignoring recent plateaus, land or sea or low atmosphere or high atmosphere, accepting or rejecting certain common attempts to correct for urban creep on measuring stations, etc. There are certainly ways in which the statement is "true", and other ways in which the statement is *false,* and additional ways in which we don't know.

The second about the Arctic icecap is definitely a bad representation. Maybe we cannot yet explain it with natural variability. But there are more causes of natural variability than we have complete locks on understanding - we don't know all the mechanisms involved sufficiently, including vulcanism, different sea water layer exchanges, the inter-relation of solar sourcing and water vapor (heck, we certainly don't know all the important causes of changes in water vapor, we only surmise some of the influence of the El Nino cycle on water vapor levels), etc. In the absence of a complete understanding of all these factors and how they cycle, it is completely nonsensical to suppose that we should EXPECT to lay out a solid claim about the limits of natural variability of temperatures. So claiming that the icecap data "cannot" be explained with natural variation is just simply beyond what science is capable of proving at this time.

And throwing in the phrase "empirical observations" was an absolute red herring. Understanding and proving the limits of natural variability is not a matter of OBSERVING data, it is a matter of using data and logic to express logical possibilities, and practical probabilities. It is a matter of reasoning with data, not just observing. There is no way to _observe_ a "limit to natural variation". Especially because our actual observations are about natural and man-made variation all tied together.

Which provides us a perfect example of what Paul and Lydia are saying. There is no way to use premises about "we cannot find a way to account for the temp change via natural variability" to arrive at "there is no possible way natural variability can account for it." Data alone can't get you there. Logic can't get you there without a lot more intermediate material than we have. (And if we ever do have sufficient material, the premise "we cannot find a way to account via natural variability" will become an irrelevancy to the final conclusion, so it is a logical null statement for these purposes.)

There is no way to use premises about "we cannot find a way to account for the temp change via natural variability" to arrive at "there is no possible way natural variability can account for it."

And from there to, "It's caused by human beings using fossil fuels" is yet another step. (It's interesting to see that when we can't account for something, somebody has a prima facie wildly implausible theory that is meant to account for it and is presented as the only remaining alternative.) And from there to, "We must impose policy restrictions to reduce human use of fossil fuels" yet another.

Tony, none of the IPCC reports that I have read (which I note no one here has linked to, and I assume, therefore, have probably not read) rules out natural variability as a reason for climate change. The point is that natural variation has been considered in all the reports and does not adequately provide an explanation for the rise in global temperature (which does not mean surface temperatures but also oceanic heat uptake).

I think all of us should read the IPCC reports in detail (and incidentally, Tony, the UHI effect on higher temperatures in urban areas has been discussed in detail). The temperature in the Arctic is indeed rising several times faster than it is in other parts of the planet, and yes, the causes of natural variability that you mention are all there (and where else would we have got these notions from?)

As for imposing policy restrictions to reduce human use of fossil fuels? I certainly think that the functioning of the "modern economy", if linked to continued and unbridled use of natural resources is neither good nor Christian or even economically justified. Absent policy changes, we would be using the highly inefficient internal combustion engines of the 1950s and 60s, not to speak of efficiencies in other areas of energy use.

Lydia, I really fail to understand what the problem with emphasising economy and frugality is. Do we really want Christianity to be connected to the "modern" consumer based economy? Was this the Christianity practised by the Fathers?

Lydia, I really fail to understand what the problem with emphasising economy and frugality is.

The problem is with the implication that _that_ is what policy proposals from AGW proponents amount to--some sort of "not difficult" and should-be-done-anyway personal frugality.


I've read substantial sections of the IPCC reports -- the problem for you is that while the science supports AGW, what it doesn't support is the notion that the climate is particularly sensitive to CO2 or that we face catastrophe (Jim Manzi has written eloquently about this later phenomenon -- the cost/benefit analysis supports at most investment in promising technology).

Here is one of my favorite writers, Steve Hayward, talking about the latest IPCC report:

Making sense of this tiresome issue requires stepping back for the long view. If you strip away all of the noise from smaller scientific controversies that clutter the debate—arctic ice, extreme weather events, droughts, and so forth—the central issue is climate sensitivity: How much will average global temperature increase from adding a given level of greenhouse gases to the atmosphere? The most recent “official” estimate of the Intergovernmental Panel on Climate Change (IPCC), given a doubling of greenhouse gases, is a planet 1.1 to 4.8 degrees Celsius warmer a century from now. On the low end of this range—up to as much as 2 degrees—warming would be no big deal, and possibly a net benefit. Warming on the high end of this range would present significant problems, requiring a number of responses. Narrowing the range of outcomes is therefore the most pressing climate science question. Everything else is a sideshow.

It may well be that it can’t be done. Right now the IPCC can’t settle on a best-guess estimate within the 1.1‑4.8 degree range, though a number of scenarios for the year 2100 cluster around 2 degrees of warming. This is nearly the same range and best guess as the previous four reports of the IPCC stretching back to 1990. More astonishing, this range differs little from that proposed by Swedish scientist Svante Arrhenius in 1896. It was Arrhenius, winner of the Nobel Prize for chemistry in 1903, who first supplied the basic equation that forms the basis for modern climate models. Working without a computer, he estimated a range of climate sensitivity from a doubling of greenhouse gases of 1.6 to about 5 degrees Celsius, with a best guess of about 2.1 degrees.

In other words, despite billions spent on climate research and the development of enormously complex computer models, we are no closer to predictive precision than we were 110 years ago. The computer models are still too crude and limited, especially about the crucial question of water vapor “feedbacks” (clouds in ordinary language), to spit out the answers we’re looking for. We can fiddle with the models all we want, and perhaps end up with one that might produce a correct prediction, but we can never be sure so long as our understanding of water vapor behavior remains sketchy.

While climate skeptics are denounced for mentioning “uncertainty,” the terms “uncertain” and “uncertainty” appear 173 times, while “error” and “errors” appear 192 times, in the 218-page chapter on climate models in the latest IPCC report released last September. As the IPCC admits, “there remain significant errors in the model simulation of clouds. It is very likely that these errors contribute significantly to the uncertainties in estimates of cloud feedbacks and consequently in the climate change projections.” The IPCC’s latest report rates the confidence of our understanding of clouds and aerosols as “low,” and allows that it is possible that clouds could cancel out most of the warming effect of greenhouse gases. If anything, our uncertainty about future climate change has increased with each new IPCC report.

More here: http://www.weeklystandard.com/articles/climate-cultists_794401.html?page=2

The point is that natural variation has been considered in all the reports and does not adequately provide an explanation for the rise in global temperature...

The temperature in the Arctic is indeed rising several times faster than it is in other parts of the planet, and yes, the causes of natural variability that you mention are all there...

I can't figure out whether you are trying to be offensively dense or what. Nobody disagrees that scientists have tried to "take into account" natural variation and causes thereof. What they don't know, don't even have a CLAIM to know, is (a) whether they have ALL of the significant factors, and (b) how they all interact. If they did, their models would be accurate - and we all know the IPCC's dismay at the fact that the models cannot generate the right results. So, while they are studying natural variation like mad, they certainly don't have a complete grip on the LIMITS of natural variation. Nor on how much man-made changes will push the temperatures.

But Jeffrey S, that's exactly the point. Mr Hayward is also correct in what he says, although he would be better advised not to regard details about these issues as tiresome. The IPCC reports do indeed stress uncertainty, and therefore complaints that the IPCC is being either dogmatic, or bullying is a misrepresentation. Why else are governments and policymakers not taking the IPCC seriously? Mr Hayward would like to stress the lower uncertainty limit of 1.1, but he knows as little (or less, seeing as he hasn't understood the science) as climate scientists, but it is equally likely (at least) to be 4.8. What then?

It is known that the earth has seen significantly higher temperatures in the past, when sea levels have been much higher. What is different today is that the major centres of population in almost every every country are located in and around coastal areas, and farming for food occupies certain areas of the earth only.

My original point was to point out to Paul that to see hectoring bluster and declarations that a debate is over is not borne out by the statements of scientists about climate change, especially in the IPCC reports, where, as Mr Hayward points out,

the terms “uncertain” and “uncertainty” appear 173 times, while “error” and “errors” appear 192 times, in the 218-page chapter on climate models in the latest IPCC report released last September.

It seems only prudent that we take steps to make out mechanical products and systems more efficient and make more of an effort towards limiting consumption, reducing waste and being more economical and frugal in our everyday lives. That is all that I have been saying, by the way, and I believe it is the Christian way, too. And following Christian prudence and frugality should not - and I'm pretty sure will not - wreck our "modern" economy either.

And Tony, I apologise for being offensive. But the study of difficult problems is beset by inaccuracies, and may indeed take a lot of time, especially where probabilities are involved. Let us not fall into the modern notion of imagining that every problem can be instantly solved. The problem, in this particular case is that in 50 years time, it is possible that CO2 sensitivities may be proven to be 1.1, in which case our efficiencies and frugality will not have done any harm. But in 50 years time, if CO2 sensitivities are shown to be 4.8, then it will probably be too late to avert the consequences thereof.

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