“But Evidence”

Asking for evidence looks easier than it seems. Sometimes it’s felicitous. Other times it leads to the purest form of sealioning. It can also be a form of abuse {1}. All depends on the relevance of the request. Is it related to a claim you committed? If not, let your opponent scratch their own itches.


There is no convincing evidence that carbon dioxide causes temperature warming beyond natural cyclical limits long observed and recorded.


What hard evidence should convince a rational person that the weather and/or climate are any worse now than 10, 100, or 1,000 years ago?


Objections and Replies

Climate Change. How can 1C in 170 years produce climate change?
☞ A 1 C warming in the climate is — by definition — climate change!

Gimme. Gimme evidence of AGW {1}
☞ Here you go: climate.nasa.gov/evidence.

Gimme direct. No, I mean gimme direct evidence of the greenhouse effect—
☞ I am not right in front of you, so it might be hard. But we know that in dry desert areas nights cool very rapidly, whereas in warm moist jungle areas it does not cools as rapidly. Is that direct enough for you? (H/T Bob Droege).

Harm. Gimme evidence that CO2 ever harmed
☞ Harm is a judgment, not an observation. Some of the CO2 is the result of fossil fuel combustion. Particulate matter kills 1 person out of 5 worldwide.

Future. Gimme evidence that CO2 will harm
☞ We do not have evidence about the future.

Laboratory. Gimme laboratory evidence
☞ Experiments give empirical results. You can use them as evidence for some other judgment, but only in an indirect way.

Metric. I’d welcome actual testable evidence and argument to
☞ Mayo or mustard in your sammich {3}?

Real-Life. Gimme real-life evidence
☞ As opposed to what? Srsly, I have no idea what you’re asking or why it would matter for the price of tea.

Undetectable. A warming of 1C in a home would likely be undetectable
☞ You should buy a new thermostat. Also note that more than one-fifth of all humans live in regions that have already seen warming greater than 1.5 degrees Celsius in at least one season.


{1} Sammich. The “give me” gives away that the square is about sammich request. A demand is more than a request. My usual reply is to ask back what ingredients the querent wants in it. Without knowing in advance what would meet a demand, it’s no use to oblige.

{} Evidence model. Evidence is never really direct, it rests on reasoning. Smoke is evidence of fire

{} Proof. Contrarians seldom ask for an engineer-level formal deduction, but sometimes they do. Such deduction does not exist in empirical sciences. Proofs belong to formal sciences.

{} Interpretation. Sometimes, different people see different things when they look at the evidence.

{} Theory. Evidence always trump theory. In theory, at least. The history of science is littered with contrary evidence.

Further Readings

2010-07. The Amazing Case of Back-Radiation.