Catastrophe
"Science begets knowledge, opinion ignorance.
PS Another point I did not answer was how a 2D mathematician could calculate 3D issues. You challenged the idea that a 2d person could perceive an orthogonal direction by saying that volumes were out of their conception.
A pertinent point but a plain would be within their imaginations. The idea that a plain intersects its own plain at 90 degrees is feasible. It would start as a dot then a line increasing in length as it intersects and then declining until it disappears. They would lack the full description of an intersection of a sphere but would be able to ascertain basic principles.
We were both correct
Cat