The Logic and Boundaries of Scepticism

In response to a couple of my recent postings, William Connolley has made what I consider to be some pretty absurd statements. The lack of logic and the imprecision of language he uses have elements in common with the more mainstream believers in “climate science”. I consider some of these below, along with other statements.


Consider the statement

You’ve failed to realise that using the label “skeptic” doesn’t actually make you a skeptic.

Equally it does not mean that a person is wrong in using the label. Given the word has multiple broad definitions, demonstrating that another is not a genuinely a sceptic1 is extremely difficult.


I am sceptical of the statement “the majority of twentieth century warming was caused by the increase in GHGs“. In a respected dictionary I find two definitions that both apply to my scepticism

  1. a person who questions the validity or authenticity of something purporting to be factual.
  2. a person who maintains a doubting attitude, as toward values, plans, statements, or the character of others.

If someone states a different definition of “sceptic“, (which they may have made up) it does not mean I am not sceptical. It just means that they are playing with words.

If someone says the statement is proven by scientific evidence they are wrong. Scientific statements are never proven, just failed to be falsified by the evidence.

If someone says that there is overwhelming scientific evidence in support of the above statement then they are wrong. There is insufficient data to demonstrate beyond reasonable doubt at the moment. There may never be the evidence, as much of stored heat energy of the climate is in the oceans. Most of the twentieth century data necessary to establish the hypothesis is missing.

If someone says of the statement I am not sceptical, but instead denying the scientific consensus they would be wrong. Firstly, the consensus IPCC does exclude the possibility that a minority of the warming was increased by greenhouse gases. Check out the 2013 AR5 WG1 SPM to verify. Secondly, even if they did make the claim, given that the IPCC has in the past made knowledge claims that it no longer holds to (e.g. radiative forcing components and the hockey stick), I am justified in being sceptical of their abilities to get it right this time.

Further, if someone says of the statement I am not sceptical due denying the scientific consensus, they are using an evaluation criteria that I reject. They are free to believe it is a valid criteria, but I believe it is equivalent to “hearsay” evidence in law.

My rejection of the claim that the statement “twentieth century warming was human caused” as being essentially true does not make me unsceptical of the weaker first statement. Nor is it sufficient to claim that I reject the IPCC Consensus, as they make even weaker statements.


If someone were to demonstrate beyond reasonable doubt that a statement were true, then I would cease being sceptical. Personally I would accept the scientific evidence at a much lower level than that in support of the statements “smoking causes lung cancer”2 or “HIV causes AIDS”3.


On reflection the last statement is not quite correct when applied to climatology. In the past I would have accepted a scientific statement based on expert opinion, or reasonable scientific evidence. But on many levels the climate community have breached the trust which any reasonable member of the public might bestow on an expert. They have failed to draw upon the accumulated wisdom of other areas, such as philosophy of science, decision theory, diplomacy or public choice economics. They have rejected things I value, such as comparing and contrasting different viewpoints, recognizing one’s own bias and listening to others. They have embraced principles I dislike, such as marginalizing opponents, and censoring of opposing opinions. But most of all many will never countenance the possibility of their own fallibility.


If someone does not reject out of hand statements of Murray Salby (who rejects the notion that the rise in CO2 levels is human caused), it does not automatically mean they accept wholeheartedly what he says. Neither does posting articles on their blog mean they believe in what Salby says. There are a number of alternative reasons. For instance, they could feel that his sacking was not justified. Or they could mean the website owner is a pluralist in science, who believes that you should not reject new ideas out of hand. Or they could believe in academic freedom. Or they could be trying to act as a forum for different ideas. Instead, using that, or similar arguments shows an inability to consider other possibilities, or to countenance that those you oppose may have valid alternative positions. It is a normal human failing to deny the humanity of others, and one that I believe we should strive to counter. Further, those with high intelligence, coupled with dogmatic beliefs, are often those most guilty of casting those with opposing beliefs as being incapable of understanding their viewpoint.


Claims that doctorates in climatology (or related subjects) confer special skills or abilities, that non-scientists do not possess is just bluster. The subject has no established track record of understanding the climate system, but has plenty of excuses for failure. It ignores many distinctions learnt in other empirically-based subjects. But most of all, the subject demands belief in a particular scientific hypothesis. Any criticism of that hypothesis, or contradictory evidence, undermines their core beliefs. Thus being too close to the subject may be a positive disability in engagement. To counter this more traditional sciences have promoted belief in the scientific method rather than belief in the scientific hypothesis. Those areas with strong ideological beliefs, such as economics and politics, have in free societies recognized the values of pluralism.

Kevin Marshall

  1. In Britain, “skeptic” is spelt “sceptic”. So I use that spelling, except when quoting others.
  2. I discussed the evidence from Cancer Research UK here following an article at “The Conversation“.
  3. AVERT, an HIV and AIDS Charity based in the UK, gives a long and through article on the case for “HIV causes AIDS“. In terms of communication of their case, there is a lot that the climate community could learn from.
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1 Comment

  1. Brian H

     /  28/08/2014

    Connolley is proof by demonstration that the contrary of sceptic is “sucker”.


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