Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard Feynman
Tiger got to hunt, bird got to fly; Man got to sit and wonder, 'Why, why, why?' Tiger got to sleep, bird got to land; Man got to tell himself he understand. -Kurt Vonnegut
So it's impossible to pledge only 1 $ now and up the pledge at a later date?
Yup, they've said it's not possible in the comments.