Cast your eyes into the pages of history if you wish to see the difference between globular reasoning at work, and true science at work. See ye Newton there, idling in his apple orchard; says he, "I fancy that the Earth is a whirling space ball", and from that moment on he thinks himself a grand scientist, and obliged to demonstrate his grandeur at all times and at any cost by preserving whatever fanciful proclamations he cared to make (in this instance the Earth's ballhood). So now suppose that some body encounters Newton, saying, "Newton, you are a liar and a fool", well he can hardly be expected to concede this, as it would be a great embarrassment. Thus he will stop at nothing to make good his initial claims no matter how ridiculous they are, when questioned as to why on (flat) Earth he might suspect such a nonsensical thing - say we ask him, "Newton, how on Earth could the Earth be a great whirling space ball?", he will readily claim, "why, because there is an invisible, intangible power pervading all across the universe which happens to crumple all things into great whirling space balls". This is the procedure of science according to the Round Earther. And if we should ask him "Wherefore this invisible power? Whither its source?", he might say, "from an invisible, intangible particle, called a graviton, which is completely undetectable by any method". And if we should scrunch our brows at this invisible, undetectable thing which Newton has detected, and voice our concerns, asking how we might discover the existence of something which utterly belies detection, he may readily say, "it must exist, because of my hypothesis", by which he really means to say that he detected it with his own imagination, so the whole of this science lies precariously on the imaginary detections of a self-proclaimed scientist. You may make what you will of the verisimilitude of such detections.
And now conceive of the zetetic scientist, Doctor Rowbotham being the paradigm of this noble profession, who enters his investigations on the question of the shape of the Earth without the bold pride to suppose it to be any shape whatsoever prior to his performing a great many experiments on it, which he does not to support some wild and fanciful hypothesis which has fallen onto his head out of thin air, but in order quite sincerely to find out just what shape the Earth is.
Now who is more likely, in these two examples, to be accurately describing the state of affairs: Newton, who will defend his original bold claim no matter if it is true or false, and will go to any lengths to substantiate it with whatever bizarre lies he can fathom and fancy, so as to avoid humiliation; or Rowbotham, who did not make any bold claim in the first place, and will simply describe what he sees before him by his own eyes, and which I see with mine own eyes, and you with your own eyes?