Inductive reasoning is often the method we scientists apply in our everyday work. We appeal to evidence — observations obtained, in the best case, under various conditions — for supporting our theories. This approach, however, bears unpleasant surprises.
Most of our knowledge, whether related to our everyday life or to our scientific activities, appears to accumulate by induction. Does the method of induction lead to relevant knowledge? Bertrand Russell in Problems of Philosophy warned us about the validity of this method. He illustrated the problem with the story of a chicken.
Once upon a time there was a chicken in a farm. This was a good and honest, empiricist chicken. He absorbed facts from around himself and learned about the nature of reality that he was exposed to. The chicken noticed an interesting thing, every day in the morning the farmer showed up and fed him. He did not really understand why that was happening but hey he got fed every day. The farmer showed up, the chicken got fed. Every single day, under all sorts of conditions, hot days, cold days, rainy days, windy days, the farmer showed up and the chicken got fed. What kind of conclusion could the chicken draw about the relationship between the farmer showing up and him getting fed? Well, being a good empiricist, allowing himself to make inferences about the laws of nature, the chicken concluded that there must be a law of nature saying: every time the farmer shows up a chicken gets fed. A different chicken, a sceptical one, asked: How do you know? How do you know that there is a law of nature that connects us being fed with the farmer showing up? The first chicken replied testily that all evidence pointed to this law of nature, that every single day of their life when the farmer showed up they were fed, that there was absolutely no evidence to contradict this.
One morning the farmer showed up and wrung the neck of the chicken. What? The chicken relied on good inductive reasoning, all evidence supported his theory, none of the evidence contradicted it and nonetheless he ended up being wrong!