Ex 7.5 Answer

The following explanation relates to the post 7.5: Resisting denial.

What is the main claim?
The main claim is that global warming, if it exists, is not a man-made phenomenon.

What are the premises?
The main premises are
1. The evidence for GW is based on inaccurate computer modelling. The first premise tries to cast doubt on whether GW exists.

2. The second premise says GW this century took place before man’s activities could have had an effect on the climate. It tries to show GW is not a man-made phenomenon.

3. The third premise says that man’s activities also contribute to ‘cooling’ gases, not just greenhouse gases. It tries to show that industry is not responsible for GW.

4. The fourth premise says that warming & cooling occur naturally. It tries to show that if GW exists, it is a natural phenomenon.

Why is it a bad argument?
Let’s examine each premise individually:

Premise 1: even if the models fail to take into account certain features, the author does not show that these are significant features. All models by necessity leave out some parts of the reality they model. What the author needed to do here is show that some significant factor had been left out. Also, he did not take into account the fact that the models may have been adjusted to allow for variation. What he needed to do here was to discuss a particular model as an example of how GW models can fail to accurately track the data. Finally, there is other evidence for GW than computer models, which the author does not mention. Indeed, the author’s opening assertion (“Despite the fact the Earth has been cooling since 1979) seems to contradict his claim in premise 1 that we cannot accurately track global climate trends. It is interesting that the author did not cite his source for that statement.

Premise 2: even if true, it does not follow that industrial activity is not now contributing to GW; indeed, this premise actually works against the author’s own point, for if 2 is true, it should be argued that it is even more important to curb such activities since they may be exacerbating a natural phenomenon.

Premise 3: does not support the claim since we have no information about the relative amounts of SO2 compared to CO2. Even though SO2 may be a cooling gas, how much, compared to CO2, is released? Given the massive industrial scale of the output of CO2 from multiple sources, it is at least unlikely that there is enough SO2 to balance out the warming effects of CO2. The author needed to cite some actual data showing that the global release of SO2 and CO2 were equivalent, or that there was enough SO2 to counteract any warming effect of CO2.

Premise 4: the mere fact that the Earth goes through periodic cycles of warming and cooling does not mean that man is not interfering in this cycle, perhaps hastening it or making it worse. What the author needed to show here was that the natural warming and cooling cycles are unaffected by the addition of CO2 to the atmosphere.

As we can see, individually, the premises can all have alternative explanations and all need further support to establish what the author claims. Collectively, they do not support each other as the author ping-pongs between one claim that GW does not exist and another that if it does it is not caused by human activity. This is a common tactic of denial arguments: no single premise is a good argument on its own, and can always be rebutted, so the denier tries to increase credibility by rapidly making one claim after another. It is a sort of “shotgun effect” in which the denier hopes to convince his reader more through weight of numbers than strength of reason. In short, this is a good example of a bad argument due to the weak relation between the premises and the conclusion.

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