the general and the universal

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?


4 thoughts on “the general and the universal

  1. Not sure about anyone making this precise distinction, but the first item, your universality, plays a big role in Donald Davidson’s case for anomalous monism – he tends to speak of ‘strict’ or ‘exceptionless’ laws (he also tends to argue for anomalous monism, but you should probably ignore that).

    I’ve heard something like your ‘generality’ called ‘scope’ or (roughly) ‘explanatory power’. It is, I’d have supposed, the main counterweight to complexity when deciding who gets slashed with Occam’s razor.

    That said, I worry ‘generality’ may have a slightly different meaning. Applying across different contexts could mean ‘across the contexts which come up often’, or ‘across many contexts that we can distinguish in principle, although none is very common’. A law that applied across ‘many contexts’ in the first sense would probably have greater scope and explanatory power, while a law that applied across ‘many contexts’ in the second sense might be thought to be more general (less ‘specific’).

    So I don’t know anyone who explicitly poses this contrast, but I think plenty of people talk about the two notions (or three), with people tending to implicitly recognise their distinctness under different labels.

    • Yes, there is something tricky to be worked out about generality. Is it true that in all possible worlds Robins tend to lay greenish-blue eggs? To answer that you need to say whether it is intrinsic to the concept ‘Robin’ that they should lay such eggs. The language of ‘cross-contextual applicability’ helps to hide that wrinkle, but possible worlds talk brings it out fairly clearly, because the mind goes to contexts which, as you say, exist in principle but don’t necessarily come up.

      I suspect the idea I’m after has more to do with contexts which come up often. Or the *relevant* contexts (which is even worse, in terms of trying to precisely specify the idea).

  2. It strikes me that the two sorts of statements differ in how we come to know them. In order to know the Sober statement (universal), we have to unravel (at least to some extent) the process by which Tigers became stripey and so to make the statement we must know the synthesis of the generalized set of facts. Whereas all that we require for the Hempel Openheim style statement (general) is an analysis of the facts that nature presents us with, the tendencies of egg colouration, birds and so on. Obviously a universal statement can be used in support of a general statement including a general statement that is stronger (implies more) than the universal statement, but the opposite is less true. Knowing about Tiger evolution might allow yo to make a universal statement about Tiger stripeness and you might then include it in evidence for a generalization about Tigers in a wider context.

    For the other way, an example that comes to my mind is that knowing that in every or most bird species egg colour is consistent in a wide band of conditions, would buttress (but would not warrant on its own) the statement that in General robin eggs are greenish-blue, by showing that such consistency of colour is possible and promoted in a wide variety of conditions similar to robin gestation. It however does not license a universal statement because it could be that in different bird species different factors hold the different generic colours of the eggs constant. In order to make the proper universal statement you would know which was operating in the robin’s egg and to what extent.

    The general statement is great for the overdetermined case, as with Ben Franklin’s statement that the only certainties in (human) life are death and taxes, however we don’t care about what you die of or which taxes you pay in determining the truth of such a sentence. You could come up with a biological universal about the aging process, probabilities of genetic and other damage and so on to show that human life would almost have to be finite, but such a construction is way stronger than what was needed to justify Ben Franklin’s claim.

    I realize this may be a complete sideline from what you are worried about, but it just struck me that this was involved with various disputes about the nature of causality, which are prominent in say Mill’s treatment of causation (aggregate view, effects are a tendency, vector addition model) and of course Nancy Cartwright (all laws are highly local contingent affairs abstracted from messy reality etc.). I realize this also may be of little interest, but I was looking through the “Generics, Laws and Context” thesis (by Alice Drewery) that was posted on your facebook wall and was heartened to notice that the author does feel her concerns have parallels with Cartwright, so I don’t think I’m making these associations up. I see other associations with (non-/)reductive explanation, multiple realizeability I assume are related to your interest…

    I would say that however causal processes work the distinction you draw between a properly constructed universal and a merely general statement could be maintained. Also, its not simply the force of the evidence, a merely general statement (that the sun will rise tomorrow) could be more credible than a universal statement (a machine that consistently produces more energy than it consumes is impossible as shown by statistical mechanics etc.).

    I realize you know this but I can’t help but think of the difference between a logical universal, the naturalistic universal you are bringing up and the (naturalistic) general statement. The general statement is stronger than the mere logical universal because of its assumption of truth across real and hypothetical variation, whereas under you description of the universal the naturalistic universal is stronger because it is derived axiomatically and implies those axioms not just the conclusion etc.. I’m sure any attempt to make the distinction more concrete than that will run into a bunch of hoary problems around the subjunctive/counterfactual conditional, defining similarity and what not…

    Interesting stuff.

    • Perhaps we can take a Kantian approach. A generalisation is an aposteriori synthetic judgment. Based on a number of registered actuals/occurences sharing feature X, I inductively infer that all instances have feature X, thus going from specifics to the genus/general.

      A universalisation is an apriori synthetic judgment. It can neither be proved nor disproved. It is a necessary condition for our experiencing the phenomenon. (critical Idealism: experiencing the phenomenon is necessary for realising that there is a universal that precedes the registration of a specific).

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