Today we encountered the scientific method employed by Sir Isaac Newton. As Newton explained, God orders the universe with laws, and these laws, specifically the ones relating to gravity, become clear to us in the practice of science. However, the causes of those laws are not obvious. That remains true today: gravity is considered a fundamental force, which is to say, it allows of no further analysis.
Newton discovers gravity by following the scientific method, as he puts it, “In this philosophy, particular propositions are inferred from the phaenomena, and afterwards rendered general by induction”. This means he starts with observations and then inductively generalizes from them. But David Hume raises problems for such inductive generalizations. All induction depends on the claim that the future will resemble the past - otherwise there would be no point in observing how things have been in the past to predict the future. But how can we justify this claim about things remaining the same? Hume points out that we cannot justify induction deductively, since it is not a logical necessity that the future will resemble the past. But we can’t justify induction inductively, since inductive arguments require the very premise - the future will resemble the past - that we would need to prove.
To shore up our worries about induction, we had a look at the grue/bleen paradox. The grue/bleen paradox gets its start from this question: How do you know that things are blue? You might say, you know because you have observed them in the past, and they were blue or green then. But all your observations would have been exactly the same if they were bleen – having the property of looking like blue things today and green things tomorrow. (In fact, as we heard in class, babies’ eyes may have this property of looking blue one day, and some other colour the next!) The problem is that all your inductive evidence for calling something blue is equally good evidence for calling that thing bleen.
Every week I'll add some information about what we discussed in class.