What is the observable universe? What can we know and how can we know it?
In terms of rejecting any observations our point of departure is never anything more than the primordial Solipsist entrapment. The logical extension of such an admission of pure subjectivity is not simply doubt but the necessary rejection of all independent observation per se. All of it. I suppose that's ground zero for an ideological rational skeptic but it's also a sort of intellectual nihilism. Once one takes the initial leap of faith beyond our sensory prison every actual occasion becomes the subject of consideration. To then reject any given set of observations as false is based in categorical presupposition. And, of course, all observers have their own. Some apparently observed occasions are objectively true and others false. Which are which is a matter of filtered judgment. A truly reasonable person brackets his own prejudicial inclinations in deference to an open mind.
Epistemology 101™ courtesy of the Cartoon Syndicate.