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How to be a real sceptic

Filed under: — gavin @ 19 December 2005

Scepticism is often discussed in connection with climate change, although the concept is often abused. I therefore thought it might be interesting to go back and see what the epitome of 20th Century sceptics, Bertrand Russell, had to say on the subject. This is extracted from the Introduction to his ‘Sceptical Essays’ (1928):

I wish to propose for the reader’s favorable consideration a doctrine which may, I fear, appear wildly paradoxical and subversive. The doctrine is this: that it is undesirable to believe a proposition when there is no ground whatever for supposing it true.

First of all, I wish to guard myself against being thought to take up an extreme position. … [Pyrrho] maintained that we never know enough to be sure that one course of action is wiser than another. In his youth, … he saw his teacher with his head stuck in a ditch, unable to get out. After contemplating him for some time, he walked on, maintaining that there was no sufficient ground for thinking that he would do any good by pulling the old man out. … Now I do not advocate such heroic scepticism as that. I am prepared to admit the ordinary beliefs of common sense, in practice if not in theory. I am prepared to admit any well-established result of science, not as certainly true, but as sufficiently probable to afford a basis for rational action.
There are matters about which those who have investigated them are agreed. There are other matters about which experts are not agreed. Even when experts all agree, they may well be mistaken. …. Nevertheless, the opinion of experts, when it is unanimous, must be accepted by non-experts as more likely to be right than the opposite opinion. The scepticism that I advocate amounts only to this: (1) that when the experts are agreed, the opposite opinion cannot be held to be certain; (2) that when they are not agreed, no opinion can be regarded as certain by a non-expert; and (3) that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.

So does this provide any clarity? Russell clearly doesn’t support an extreme where everything must be continually doubted and nothing can ever be known. As he later suggests, that kind of position would make it philosophically troubling to ever get out of bed in the morning. This extreme attitude does however rear up in climate discussions where an interesting debate on the impacts of human-related increases of greenhouse gases on, say, the atmospheric circulation, often becomes bogged down in how do we know that GHGs are increasing at all, whether they are affected by human activity, and how it’s all down to the sun anyway. Since all of these things have been discussed ad nauseum here, here and elsewhere, that kind of ‘scepticism’ (more accurately described as contrarianism, or ‘la-la-la-I-can’t-hear-you’-ism) serves only to waste time. Since working scientists are all busy people, this is usually why we tend to cease communication with such contrarians very quickly.

If we relax the above-mentioned constraint requiring ‘all experts’ to agree (something never achieved in practice) to ‘the overwhelming majority of experts’, we can substitute in the IPCC for ‘experts’ in the quote. It’s important to note that Russell does not claim that if all experts are agreed, then one must agree with them, but solely that being certain of the opposite opinion in such circumstances is not wise. It is implied by his opening statement then that having ‘all experts’ agree something is reasonable grounds for supposing something to be true. Similarly, if the IPCC concludes that something is highly uncertain (such as the magnitude of changes in aerosol indirect effects), then there are no good grounds for assuming otherwise.

Can someone be productively sceptical? Of course. Firstly, one needs to be aware that scepticism about whether a particular point has been made convincingly is not the same as assuming that the converse must therefore true. Sometimes scientists just don’t use the best arguments they could (particularly if they are a little out of their field of expertise) and these points can, and should, be challenged. One example would be the use of an incorrect ‘correlation implies causation’ argument. For instance, the strong correlation of CO2 and temperature in the Antarctic ice core records does not in and of itself imply that CO2 has a radiative impact on climate. However, additional analyses that look at the factors controlling temperature during the ice ages give strong grounds for believing that CO2 does play an important role. Therefore while the use of the correlation argument alone is wrong, the converse of the conclusion is not necessarily true.

Secondly, it helps to have done the homework. It is highly unlikely (though not impossible) that the sceptical point in question has not already been raised in the literature and at meetings. If a particular point has been argued to death previously and people have moved on (either because it was resolved, moot or simply from boredom), there is little point bringing it up again unless there is something new to talk about. Obviously, a good summary of how the point was dealt with can be educational though. Arguments about whether the current CO2 rise is caused by human activity fall clearly into this category.

Thirdly, scepticism has to be applied uniformly. Absolute credence in one obscure publication while distrusting mountains of ‘mainstream’ papers is a sure sign of cherry picking data to support an agenda, not clear-thinking scepticism. Not all papers get the peer review they deserve (or require) and the literature has many examples of dubious logic and unsupported interpretation. Sometimes this becomes very clear (for instance, the Soon and Baliunas saga at Climate Research), and sometimes it goes uncommented upon. But what about Galileo? Wasn’t he an obscure scientist persecuted by an entrenched mainstream? Yes, but Galileo is celebrated today because he was correct, not because he was persecuted. If an idea is right, it will be supported by additional evidence and will lead to successful predictions – at which point it will likely be accepted. The ‘Galileo’ defence (and its corollary the ‘establishment conspiracy’) are usually a sign that the additional evidence and the successful predictions are lacking.

Finally, it should be understood that constructive scepticism is a mainstay of the scientific method. The goal of science is to come closer to a comprehensive picture of how the real world works, with scepticism essential to toughening up scientific ideas, though alone, it is insufficient to move understanding forward. It isn’t essential that every true sceptic have an alternative theory ready to go, but they should bear in mind that our picture of how the world works, though incomplete, rests on many different foundations. If it sometimes seems that the scientific consensus is resistant to new ideas, it is because that consensus has already been tested in many ways and yet still stands.

Much of what passes for ‘debate’ on climate change in the popular media, is often framed as the ‘scientific consensus’ vs. the ‘sceptics’. A close examination of these arguments (for instance, as outlined in a recent Wall Street Journal editorial) doesn’t reveal much that could be described as true scepticism since they often use the fallacious reasoning that we discuss above. However, since scepticism has a (justifiably) long and noble tradition in science, the framing device is quite powerful (despite the lack of connection with any actual scepticism). As with the intelligent design controversy, agenda-driven opposition has often managed to cloak its contrarianism with the mantle of scepticism. So, while many contrarians pay lip service to the legacy of Russell (or even Pyrrho), forgive me if I remain a little sceptical…

210 Responses to “How to be a real sceptic”

  1. 201
    Hank Roberts says:

    > 197, 200:

    ” … global warming can lead to lots of strange local climate change. At several research stations in the study, scientists have found that the maximum daytime temperature has actually gone down. At night, on the other hand, the minimum temperature has been going up. Clouds may be causing this pattern ….. as nights get warmer, the mid-elevation forests are becoming the perfect breeding ground for the fungus. And harlequin frogs there have paid the price.

    …. pseudo-skeptics try to claim that we can’t learn anything about extinctions or how they might be accelerated by future climate change …. The equation is far from simple. … as far as I know, no one predicted that it would be nighttime warming and daytime cooling that would make the fungus so deadly. …. “

  2. 202

    Re Maurizio’s whole thread — it seems to me like he’s been handed EXACTLY the evidence he asked for, and dismissed all of it. I’ve run into this type repeatedly on AOL message boards and in chat rooms. Arguing with this guy is pointless. There’s nothing you can say that will convince him. It’s very much like beating your head against a wall, and our best response to it would be “it feels so good when I stop.”

  3. 203
    Pat Neuman says:

    High humidity decreases rates of temperature decline overnight and rates of temperature rise in the day. The dust bowl of the Great Plains (early 1930s) had low humidity and high daytime temperatures (above 100 F).

  4. 204
    Maurizio says:

    Barton Paul (202): I have even provided a list of what would convince me. Can’t imagine how I can be more honest than that

  5. 205
    Maurizio says:

    About the trouble of working just with “trends”: look at the USGS earthquake statistics at

    Here’s the total number of quakes from 1990 to 2005

    1990 16590
    1991 16484
    1992 19524
    1993 21476
    1994 19371
    1995 21007
    1996 19938
    1997 19872
    1998 21688
    1999 20832
    2000 22256
    2001 23534
    2002 27454
    2003 31419
    2004 31194
    2005 29867

    There is a clear upward trend that would make any IPCC committee salivate twice over…is there perhaps an upcoming Nature paper linking earthquake activity and man-made greenhouse gases???

  6. 206
    Maurizio says:

    Dano, Coby and Lloyd (several comments): How should I reconcile your statements about there being no incontrovertible proof for global warming of the dramatic kind I have been waiting for, with the gloomy forecasts recently published by James Lovelock (not to mention the End-of-the-World-is-Nigh from one of the recent Fortune magazines)?

    If “Before this century is over, billions of us will die” (Dr. Lovelock’s text, not mine), is that going to happen all of a sudden, will it all be a matter of weather extremes (remarkably, without a single weather pattern moving anywhere) or will we be graced with a few “incontrovertible proofs” that global warming is indeed going to kill us all?

    Methinks there is a lot in common with all these disaster articles, and the dire predictions years ago about the impending population disasters that never were

  7. 207
    Hank Roberts says:

    > earthquakes
    Bogus. Careless or wilful misrepresentation, see footnote on linked page.

    > As more and more seismographs are installed in the world,
    > more earthquakes can be and have been located. However,
    > the number of large earthquakes (magnitude 6.0 and greater)
    > have stayed relatively constant.

  8. 208
    Coby says:

    Dano, Coby and Lloyd (several comments): How should I reconcile your statements about there being no incontrovertible proof for global warming of the dramatic kind I have been waiting for, with the gloomy forecasts recently published by James Lovelock (not to mention the End-of-the-World-is-Nigh from one of the recent Fortune magazines)?

    I think, Maurizio, you are falling into a very common trap, so I will not be too harsh on the lack of logic in the question you ask above. The trap is to view this issues as “us versus them”, two poles, chose your side etc. This is shallow to the point of being doomed to fail in providing any insight whatsoever. I don’t think you mean it.

    But here’s the answer:

    First, what is there to reconcile? I am not James Lovelock, he is not me. He has his own opinions, anyone who makes the minimal effort to understand this issue will have their own.

    Second, he is telling you what he thinks will happen, I don’t think you will catch him ever saying or thinking that their is incontrovertible proof it will be so.

    Third, he is talking about what the future holds, not what we are reading in the newspapers of journals today, which is where you are looking.

    Because of the nonsensical nature of your question, I think you are just being inflammatory. You are also now exhibiting all the hallmarks af a septic, not a skeptic, making obvious errors in logic, unsupportable assumptions about what others believe etc, not to mention the mocking tone you adopted in comment #205. We can do better than that, even in the face of disagreement.

    As for incontravertible proof, it is true you presented a list of what you would accept. But you did not at all address my questions to you about why those things are proof but everything else we see happening isn’t.

    I’ll be frank with you, I don’t believe you that any of those things would be any more convincing to you. As I said before, the Sahara was not always a desert, if it turns green now how will you prove that is due to global warming? What do you know about the history of monsoons before the emergence of record keeping in asia? They may not have always been there.

    If you ask me, the day these drastic changes do come will be far too late to do anything about it. And there will still be people denying that it was our fault.

    You have never been very clear about what it is you want proof for. Are you sceptical that the temperature is rising? Changing weather is hardly needed to prove that, just look at the temperature records. Do you need proof that it is because of anthropogenic influence? I repeat what I said above (and you never addressed) there is quite simply no proof possible. There can only ever be statistical correlations, sophisticated model output and internally consistent theories that explain all of the available evidence. You need multiple planets to run experiments on for anything better. Are you sceptical that a rise in temperature will be bad? That is the only place where intelligent scepticism still has an excuse, though again the balance of evidence says we need to worry about it.

    I worry when discussing with people who do not make it clear what they do except and what they still doubt. Maybe if you cleared that up some useful discussion could still ensue.

  9. 209
    Pat Neuman says:

    re 205 Maurizio wrote … About the trouble of working just with “trends”…

    Trends by themselves are insufficient. Understanding the trends is required.

  10. 210

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