An amusing thing about a hypothesis like "all swans are white" is that if you do want to go around making observations to support it you don't actually need to observe any swans.
"All swans are white" is logically equivalent to "All non-white things are not swans". Thus you can gather observational evidence for the hypothesis by finding non-white things and checking if they are swans.
My monitor is not white, and I see it is not a swan. I've just made an observation in support of "all swans are white". I can make hundreds of such observations without even leaving my house.
I feel sorry for all those other swan color researchers who had to trudge around slimy rivers and mucky wetlands checking the colors of swans.
I think I first saw this in a Martin Gardner book. It is amusing, but actually there has been quite a bit of serious work among logicians and philosophers over this [1] since the logic seems correct but intuitively it seems you shouldn't be able to research swan color by looking around at the furniture in your house.
