I’m hoping to draw on the collective wisdom of the internets here. There is a distinction that could be very useful to my thesis, and I feel sure that someone must have made it already, but I can’t for the life of me think of who or where. Any help identifying a prior source for this would be most appreciated.
The distinction is between what I’ll call the general and the universal. Roughly, things that are universally true are true in all cases, whereas things that are generally true are true across contexts. Put like that there doesn’t seem to be much difference, so let me try to make it clearer.
Consider two putative biological laws. From Hempel and Oppenheim (1948), we have the proposed law “All robin’s eggs are greenish-blue”. Now that may seem odd to modern philosophers of science, because it’s unlikely that there has never ever been a case where, due to random mutation or dietary oddness or whatever, a robin has laid an egg that wasn’t exactly greenish-blue. But at the same time, we can say that, in general, robins do indeed lay greenish-blue eggs.
Now consider a different proposed biological law, from Sober(1997) : he suggests that if we’re worried about the presence or absence of laws in evolution, we can easily build them by including in the antecedent of our law all of the ecological conditions which lead to a certain phenotype coming into being. So Sober’s laws look something like,
If X ecological conditions obtain, then for all Y’s, Y’s will evolve to have Z trait.
Instead of just saying “All tigers are stripey”, we say, for all tigers that evolved in such and such a context, those tigers will have stripes.
So the distinction I want to make is between the generality of Hempel and Oppenheim’s law about robin’s eggs, and the unviersality of Sober’s laws of biology. Sober’s laws will always be true, because (by hypothesis) we built into their antecedent enough detail to ensure that the consequent will always follow. They are true in all cases. However, because we specified it so particularly, the antecedent will very likely obtain in only a few extremely specific circumstances. His laws therefore have very little cross-contextual applicability.
On the other hand, Hempel and Oppenheim’s law about robin’s eggs has pretty good cross-contextual applicability. We can vary quite a lot about the background conditions in which robins live, and they’ll still (mostly) lay greenish-blue eggs. The average temperature can change, the kind of trees they live in, the sort of predators they face, and probably their food sources can be varied fairly widely, and still they’ll (mostly) lay greenish-blue eggs. Of course, their law has limited generality – there will be background conditions under which robins cease to lay greenish-blue eggs, or even where robins will fail to exist at all. But I think it’s obvious that Hempel and Oppenheim’s purported law is much more general than Sober’s.
So that’s it. Generality versus universality. Universality is just about whether we can stick a universal quantifier on our conditional – in all cases, if X then Y. Generality is a modal concept, about invariance under variation. It’s about the antecedent of a conditional – across how many contexts can we reasonably say that X obtains, such that our law is even relevant at all?
Someone must have made this distinction, I’m sure. Any suggestions?