There are certain propositions which philosophers, at one time or another, have said we "unthinkingly assume" or "instinctively believe". One such proposition is that there are about us entities, "physical objects", which can and do exist unperceived. To say that this is something we unthinkingly assume is to imply that it is a matter for dispute whether it is true. Talk of "unthinking assumptions' is thus tied up with the idea that the philosopher's job is somehow to justify, or else show to be unjustified, what we ordinarily neither question nor think of questioning.