The Black Swan?
Popper’s falsification approach might be a good logical exercise but that’s not how science is done. We often can’t know if a phenomenon falsifies a theory. There are way too many factors. Since I am not a philosopher, I will narrate a personal anecdote that might illuminate matters. This happened during the time I was in the beautiful city of Delft doing my research. As some would know, Delft is full of canals that are inhabited by all kinds of birds. One evening as I was walking back to my house from the TU (Delft University of Technology), I saw a black swan in one of the canals near my house. I was rather excited and pleased to have seen it. Since it was evening time, and the light was not so good, I couldn’t see it quite clearly. Anyway, long story short, as I approached nearer, much to my dismay I realized it was not a black swan but rather a poor old white swan, which had become black due to the dirty water, worsened no doubt by the litter that the boisterous undergrad students of the TU had thrown into the canal!
In Popper’s logical world, when we see a black swan, we know it’s a black swan, a falsifying piece of evidence, and that’s the end of the story: the hypothesis “all swans are white” has been efficiently falsified! But it doesn’t work like that in the real world. Of course, my anecdote is rather simple, the situation is much more complex when dealing with all kinds of noisy data that can “falsify” most theories.
Just one last thing, things would not work so simply for the falsification approach, even if we just took the above simple anecdote. Next, I will try and argue why the so-called problem of induction still stands tall and proud. Let me explain. Imagine some time after my experience in Delft, I go to Australia and see an actual black swan. However, since I have been ‘burnt’ by my earlier experience in Delft, I refuse to jump to the conclusion that it is indeed a black swan. I decide then to test if it is really a black swan or if it has been blackened due to litter and pollution. It is a simple test. I take the bird and wash it with soap. Upon washing it thoroughly, I see that it’s still black. Voila, problem solved. “All swans are white” has been falsified. But wait a minute. Not so fast. How can I know that I did a good job of washing it? Hmm. No problem, I wash it again. It is still black. Are we done? No, not really. How can we be sure? Ok, I get down to business and keep washing the bird till late at night. By the time I am done, I have washed the swan a thousand times 🙂 And it is still black. I am really tired. Can I go home now? Can we all agree that it is a black swan, and not a white swan that has become black due to pollution? Sorry, not really: we have no idea what would have happened when I would have washed it for the 1001st time! And thus the problem of induction stands proud, entertaining no easy logical solutions!
I note that the above paragraph was simply a fun, logical exercise. It is not the central “thesis” of this post. What I really wanted to say is that practically speaking, putting it simply, science doesn’t follow the falsification approach due to the problems identified in the personal anecdote in Delft: One almost never knows if a phenomenon falsifies a theory. There are way too many factors. In the case of the blackened swan in Delft, the factor became known (pollution). But often the factors are unknown. Therefore, scientists don’t rush to discard theories based on such ‘evidence’.
So for example, consider Galileo. He couldn’t explain why objects were not flying off the surface of the earth if the earth was rotating. That was a clear piece of falsifying evidence. Let’s consider Darwin. Darwin’s data was telling him that the gradualist program of evolution was false. Data suggested that evolution was in clear and distinct stages. So the gradualist program was falsified by the data but Darwin ignored it (of course, now many agree that evolution is indeed not always a process of gradualist fine-tuning, but that’s another matter). Mendel did the same and he simply ignored a lot of the falsifying data. At a much narrower level, every experimenter knows that many experiments come out the wrong way, and therefore are reanalyzed and discarded – or sometimes just put on the shelf.
(Endnote: As for the many self-professed Popperian scientists, I refer the reader, as I did in my post on Tolstoy, to Nigel Gilbert and Michael Mulkay’s sociological study, “Putting Philosophy to Work: Karl Popper’s Influence on Scientific Practice”. It shows that scientists might say that they are following Popper, but really they are doing nothing of the sort. A further corrective would be Einstein’s words about scientists and their ‘method’: “Don’t listen to their words, fix your attention to their deeds!”)