Now, Shaw is exaggerating, but there is something in what he says, and the question is worth following up, for the sake of the light it throws on modern knowledge. Just why do we believe that the earth is round? I am not speaking of the few thousand astronomers, geographers and so forth who could give ocular proof, or have a theoretical knowledge of the proof, but of the ordinary newspaper-reading citizen, such as you or me."
This is by George Orwell, who goes on to explain his reasons for thinking the earth is round.
"It will be seen that my reasons for thinking that the earth is round are rather precarious ones. Yet this is an exceptionally elementary piece of information. On most other questions I should have to fall back on the expert much earlier, and would be less able to test his pronouncements. And much the greater part of our knowledge is at this level. It does not rest on reasoning or on experiment, but on authority. And how can it be otherwise, when the range of knowledge is so vast that the expert himself is an ignoramous as soon as he strays away from his own speciality? Most people, if asked to prove that the earth is round, would not even bother to produce the rather weak arguments I have outlined above. They would start off by saying that ‘everyone knows’ the earth to be round, and if pressed further, would become angry. In a way Shaw is right. This is a credulous age, and the burden of knowledge which we now have to carry is partly responsible."
Of course, this was before pictures of the earth from space...