Wednesday, February 24, 2010

The Logical Fallacies of Anthropogenic Global Warming

Climate-Gate has certainly dealt a tremendous blow to the validity of the Anthropogenic Global Warming (AGW) theory, but some die-hard ignoramuses continue to assert it is true.  Aside from outright reductio ad absurdum, AGW enthusiasts also frequently justify their belief using logical fallacies.  I will cover a few of the more common logical fallacies (note that these are commonly used to defend many other ill-contrived ideas):

Fallacy of Affirming the Consequent

This is arguably the most oft used fallacy in the AGW debate.  It's exhibited in statements like, "Global Warming is obviously happening because glaciers all over the World are melting."  However, there are a lot of reasons why glaciers melt.  In fact, glaciers have been melting ever since the ice age concluded - far earlier than the supposed commencement of man-caused global warming.

In fact, the assertion that the Earth is warming as a result of man made greenhouse gases (namely CO2) is itself a fallacy of affirming the consequent because there may be many reasons the Earth is warming (assuming, of course, that the Earth is actually warming).  This fallacy can be spotted wherever someone is making the claim that a consequence is occurring as a result of a specific event or condition when there are other explanations that have not been eliminated from possibility.

The Fallacy of Appeal to Authority

The AGW faithful commonly claim that their position is valid because, "like, all the scientists say it's true!"  This is the fallacy of appeal to authority (and is also flatly inaccurate).  There is only one truth; even if every single living person earnestly believes something to be true doesn't necessarily make it so.  It is not enough for "experts" to simply say something is true - the truth stands on its own and only through the use and understanding of incontrovertible facts can an expert, or anyone, come to understand the truth.  Experts are individuals with a vast amount of knowledge in a particular area, but they're not infallible.  People don't make the truth, they discover the truth.

A good example is NASA's Dr. James Hansen, a favorite AGW expert of Al Gore's.  If relying on the expertise of "experts" such as Dr. Hansen was reliable, then we should be in the midst of an ice age because Dr. Hansen was among the "experts" declaring we were on the verge of it in the 1970s.  Apparently, his flawless scientific mind made a goof and we were really on the cusp of a global warming epoch - or, perhaps, he was just confused about the freezing temperature of water.

The Fallacy of Reification

 "The science clearly says mankind is causing the Earth to warm catastrophically."  No, science does not, and cannot, say anything.  People say things; as such, people must interpret scientific knowledge, observations, and data.  Then they present their findings.  Clearly, what is really intended by the quote is that an "expert" says something which refers back the previous fallacy, but what is connoted is that somehow the facts are self-evident although they most certainly are not.

The Fallacy of Ad Hominem

This fallacy is always presented when someone has no viable argument nor logical basis for his or her position and is a favorite among AGW fanatics.  "You're just not evolved enough to understand the science!"  Demeaning an individual, group, or competing idea is the lowest form of debate because it both fails to support the person's argument or defeat his opponent's position, and it has no relevance to the issue.  If someone is resorting to the fallacy of ad hominem he is doing so in a feeble attempt to discredit the person - most likely because he believes appeals to authority are valid proofs and if an opponent is discredited then she would be unfit as an authority.

The Fallacy of the False Dilemma
This fallacy can be more difficult to spot, but it is also very prevalent in the AGW debate.  For example, "either you realize that AGW is occurring or you don't think humans have any affect on their environment."  In this case, the false dilemma is between agreeing with AGW or believing that humans have no impact on the environment.  Realistically, you can comprehend that humans affect the environment, but causing calamitous worldwide warming isn't part of some make believe, all inclusive humans-ruin-the-Earth package.

Another example would be, "If you don't believe in AGW then you don't believe in science."  Quite to the contrary actually.


While I could fill books with example after example of logical fallacies in the AGW debate, this should provide a succinct summary of the most common classification of fallacies often relied upon by the AGW faithful.  Should you find yourself in a debate on this topic be sure to point out to your opponent his use of these fallacies.  When you consider all the arguments presented as proof of AGW, they all fit within one of these categories (or possibly another logical fallacy not listed here).  The two tenets of AGW are the correlation between atmospheric carbon dioxide concentration and global average tempertaure and the climate computer models.  While not strictly a logical fallacy, correlation never proves causation - and the correlation is pitiful; it is only made presentable by using annual global average temperature variants because using raw data would render it completely statistically void.  Computer models are only worthwhile if they can be validated and a global climate model can never be validated, not to mention that pesky little detail that the models have already failed to correctly predict average global temperatures.  Finally, never forget the most important question, "What exactly is the correct temperature for the Earth?"


  1. Where does the "Big Lie" fit into the logical fallacies? "The Big Lie" being that "Global Warming" is a problem. It is not, a warmer world would be a better world.

    Steve Case

  2. I think this is more about the rules of debating rather than logic.

  3. Logic, or lack thereof, is used in debate and in reasoning. Use this for debating, or use it to develop your own conclusions. I don't see how it pertains solely to debate.

  4. Your "The Fallacy of Appeal to Authority" is wrong. That pertains to a specific expert making a controversial claim.

    95% of climate scientists (over 30,000) believe that AGW is happening. That's a robust scientific consensus.

    To argue that this is an appeal to authority, is like believing in geocentricsm and saying that you can't cite those scientists who believe in heliocentricsm because it's an appeal to authority.

  5. Chris,

    Please observe a critical distinction: geocentrism is disproved by simple observation - no interpretation of the "data" is required. It has nothing to do with the number of scientists that believe in geocentrism versus the number that believe in heliocentrism.

    Where did you get the idea that the fallacy of appeal to authority is limited to one expert making a controversial claim? It's a fallacy because the statement of experts is worthless without evidence behind their assertion. The number of so called experts agreeing or disagreeing is moot. Keep in mind, these same experts (e.g. Dr. Hansen - NASA) warned of the coming ice age in the 1970s. Clearly, they missed the mark then as well.

    Similarly, if 100% of climate scientists believed in AGW it still wouldn't make it true. It's a fallacy no matter how many scientists, engineers, politicians, graphic artists, journalists, or whomever believe it to be true. I'm not aware of facts that are decided by consensus vote. Is the second law of thermodynamics considered a "law" because most scientists believe it to be correct, or because it has been shown, repeatedly, through experimentation to be correct? Your first clue should be the use of the word "believe" because it immediately reveals the non-scientific nature of the issue.

    Out of curiosity, what convinces you that AGW is real? Is it that a gaggle of scientists are telling you so, or do you have something more substantive upon which you're basing your conviction?

    Finally, also out of curiosity, what is your reference for the 95% of climate scientists (equal to 30,000) that believe in AGW?

  6. Weren't there also 31K scientists who disagreed with the AGW thesis?