what persuade gulliver not to reject captain wiliam robinson proposal

Gulliver couldn't reject Robinson's proposal because it was so attractive; head surgeon, double the pay, and complete respect for any advice he had to give. He couldn't have asked for more....... especially when his desire to travel was as strong as ever.

"...he plainly invited me, though with some apologies, to be surgeon of the ship; "that I should have another surgeon under me, beside our two mates; that my salary should be double to the usual pay; and that having experienced my knowledge in sea-affairs to be at least equal to his, he would enter into any engagement to follow my advice, as much as if I had shared in the command."

He said so many other obliging things, and I knew him to be so honest a man, that I could not reject this proposal; the thirst I had of seeing the world, notwithstanding my past misfortunes, continuing as violent as ever."