Humans have cognitive biases that can affect our judgments. One of these cognitive biases is the confirmation bias. Because of the confirmation bias, we tend to seek the information confirming our preexisting beliefs.
Confirmation bias is a fact of life, and all humans have it. Confirmation bias can result in different subjective opinion from a different subject. A characteristic of any pseudoscience —like the concept of flat-Earth— is that they don’t try to minimize the confirmation bias, but they actually encourage it.
It is not hard to see a lot of this going on in the community of flat-Earth victims.
- The ‘experiment’ of receding sun, done on a curved desk.
- The crepuscular ray ‘experiment’, failing to account for the observer distance.
- The solar eclipse ‘experiment’ using a directional flashlight, smaller than the Moon and Earth models, concluding that the shadow cannot be smaller than the Moon.
- The observation of a sunset with autoexposure turned on, resulting in size changes of the sun depending on the zoom factor.
In those cases, they didn’t attempt to do an objective measurement, control the confounding variable, or retry the experiment using different parameters.
Maybe they did retry the experiment using different parameters, but only the experiments that confirm their biases are published.
The scientific method is designed, among other things, to minimize the cognitive biases, like the confirmation bias. An experiment that done without controlling these bias can never be accepted in science; because it might tell more about the persons who did the experiment, rather than the experiment itself.