>There are several well reasoned arguments that the Earth is spherical (e.g., the shadow of the Earth is curved). That argument would prove the Earth is round

>There are several well reasoned arguments that the Earth is spherical (e.g., the shadow of the Earth is curved). That argument would prove the Earth is round - but not necessarily that it is spherical. A flat, round disc would also produce a curved shadow. To play devil's advocate - you would also need to prove that it is Earth's shadow on the moon and not the Sun's shadow. For an example, I made an HD image in paint [0]. [0] https://vgy.me/8xRkJv.png https://vgy.me/8xRkJv.png