The larger point Kuhn is getting at is that early adoptees of new theories rarely do so “because of any scientific merit”, but rather because the new theory appeals to them on a personal or aesthetic level. Novel theories, like those of Copernicus and De Broglie, often do a worse job of explaining the evidence than their established rivals, and early adoptees are essentially making a leap of faith in defiance of the bulk of the evidence. Only through the work of these early, ‘irrational’ adoptees are the rational reasons for adopting the new theory uncovered.
The larger point Kuhn is getting at is that early adoptees of new theories rarely do so “because of any scientific merit”, but rather because the new theory appeals to them on a personal or aesthetic level. Novel theories, like those of Copernicus and De Broglie, often do a worse job of explaining the evidence than their established rivals, and early adoptees are essentially making a leap of faith in defiance of the bulk of the evidence. Only through the work of these early, ‘irrational’ adoptees are the rational reasons for adopting the new theory uncovered.