December 4 – In The Black

Today’s factismal: The black swan is the only animal with a logical fallacy named for it.

Back in the 1900s, there was a great debate about how to define science. Was science just what scientists do? Or was it the breaking down of big things into little ones and examining the pieces to look for a pattern? Or was there a scientific method behind the science madness? For many, that debate continues today. But one of the more interesting things that came out of the debate about what scientists do was a useful distinction about what scientists say.

These are white swans. But do they prove that all swans white? (My camera)

These are white swans. But do they prove that all swans white?
(My camera)

Karl Popper noted that there are two types of statements that dominate science. The first is a simple observation, such as “that is a white swan”. The second is a categorical statement, such as “all swans are white”. The first sort of statement is pretty easy to prove; you just ask someone else to look at the thing you see and tell you if it is (a) a swan and (b) white. But the second sort is fiendishly difficult. Just because you see one white swan, that doesn’t mean that all swans are white. And just because you see a thousand white swans, that doesn’t mean that all swans are white. As a matter of fact, you could look at as many swans as you wanted and not be able to prove the second sort of statement because you might not have brought in all of the swans that exist.

These black swans were once thought to be mythical (My camera)

These black swans were once thought to be mythical
(My camera)

So Popper proposed a different way of checking the second sort of statement. Rather than trying to bring in every swan that exists, Popper said that a scientist would accept the second statement provisionally (and call it a hypothesis) and look for evidence that disproved it; the scientist would try to falsify the statement. Thus, before seeing a black swan a scientist would say that because all of the swans that he’s seen are white all swans are white and after seeing a black swan the scientist would say that the hypothesis that all swans are white is wrong. That’s why scientists don’t get too upset when their ideas are shown to be wrong – because they always knew that they could be wrong. And that’s why falsifiability is central to science.

Of course, in addition to providing a great example of how science works, the black swan is a simply beautiful bird. They live in wetlands and salt-water marshes along the southern and central east coast of Australia where they munch on small plants. And the Europeans who found them in 1697 met with the same skepticism that greeted the platypus (i.e., “there ain’t no such critter!”); it wasn’t until a pair of black swans were sent to Holland that the black swan was changed from a fallacy to a reality. If you’d like to learn more about black swans or report seeing one, then swim on over to MySwan:

2 thoughts on “December 4 – In The Black

  1. Pingback: January 5 – Happy New Bird! | Little facts about science

  2. Pingback: February 2 – Lord Love A Duck | Little facts about science

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