Science and Common Sense

For various reasons I was playing around with ways of summarising what is distinctive about Lewis’s contributions to philosophy, and I thought the following idea sounded interesting. I’m not sure whether it also sounds true, but I thought I’d put it forward for consideration.

One of the signature tasks of philosophy is to figure out the relationship between science and common sense. By ‘common sense’ here we don’t mean platitudes that people utter, as much as the tacit knowledge that lets us navigate the world successfully without sufficient explicit knowledge to pass any given tenth grade science course. Making that tacit knowledge explicit is one of philosophy’s tasks, and one at which Lewis excelled, but perhaps less crucial than relating it to the scientific image. Four options stand out here.

First, we could say that science has shown that common sense is badly wrong, and in need of radical overhaul. This way lies eliminitivism.

Second, we could say that common sense shows that science is either wrong or, at the very least, incomplete. Various forms of dualism and idealism lie this way.

Those two options say there is a tension between science and common sense. The next two options are for reconcilation.

So third, we could say that proper appreciation of science as we find it reveals a place for our common sense concepts. Various forms of naturalism, at least as that term is understood in America, go this way.

Lewis promoted, and to a large extent pioneered, a fourth way. By investigating the structure of common sense closely, we find that it is fit to be reconciled with science, almost any way that science turns out will turn out to be compatible with common sense.

This kind of approach, if it works, allows you to keep two of Lewis’s distinctive attitudes, attitudes he often displayed side by side. First, it’s not an open scientific question whether there are, say, psychological states such as beliefs and desires. Second, philosophy can’t overturn what science shows us. If we go with option three (not to mention option one), there is a danger that science will overturn tacit folk knowledge. That would be bad. If we go with option two, we’ll be using philosophy to overturn science. That would be worse. So option four it is.

The trick then is to make common sense fit for science, roughly however that science turns out to go. Lewis’s strategy here has three parts.

First, show that the ontological and ideological commitments of common sense (or at least the bits of common sense we are committed to keeping) are thin enough that science is guaranteed to meet them.

Second, provide a broadly functional analysis of common sense concepts, passing the question of what realises those functional roles to science. The functional roles are specified in a Wittgensteinian ‘near-enough-is-good-enough’ way, so as to maximise the chance that science will find realisers. (I don’t distinguish here between theories that provide functional definitions of folk terms, theories that provide rigidified functional definitions, and theories that take functional roles to be reference fixers, though that’s something we’d like to know when we do the details.)

Third, provide a broadly subjectivist account of those folk concepts that don’t look like science will find distinctive realisers for them. Lewis’s subjectivism about ethics and contextualism about epistemology fit into this part of the project.

At every stage the devil is in the details, but we can see a way to carry out option four in this outline. A large percentage of Lewis’s work can be seen as carrying out this three-step plan.

If this is the right picture in outline, then these paragraphs would be an introduction to a work saying how Lewis carried this off. That work would probably be book length, so I won’t try it here. But I wonder what people think of the broad story?

12 Replies to “Science and Common Sense”

  1. Before any other comments come in, let me note three disclaimers.

    First, Lewis did sometimes work that looks more like my option three, fitting existing science into common sense. The paper on QM in the special AJP issue is in this tradition.

    Second, Lewis’s work on religion was obviously more eliminitavist than his other work. (Though even there he was largely carrying out option four. Recall his sometime worry that common sense itself was irreligious, so his religious friends were being incoherent. Here he would have preferred option one to option four.)

    Third, some technical work, e.g. work on formal semantics and perhaps work on philosophy of maths, doesn’t fit into this story at all, because it’s not about the science/common sense relationship. The story I’m telling here doesn’t cover all of philosophy, though it does cover a large part of it, at least for Lewis.

    Also one clarification. ‘Common sense’ here means regimented common sense, and Lewis’s preferred regimentation included some things we would not normally include in the common sense picture of the world, most famously concrete possible worlds, but also temporal parts. Here Lewis does increase the ontological burdens of common sense, but not in a way that science could ever show to be mistaken.

  2. What would be bad about science overturning tacit folk knowledge?

    It is a good thing when science overturns the folk physics platitude that heavy things fall faster than light things. And such examples aren’t obviously relegated to folk physics. It turns out that people tend to systematically mess up in mind-reading by overestimating the extent to which their knowledge is shared by their interlocutors. If we’re willing to be theory theorists on this issue, then, we should take it that science has shown that folk psychology contains some false platitudes about the extent to which our interlocutors share our knowledge.

    These results seems like the sort of thing we philosophers should welcome, not the sort of thing that our methodology should be purposely designed to avoid. I suppose Lewis has a snappy answer to these points, though.

  3. Dennis,

    I think it’s not bad (for Lewis) when science shows that folk theories are mistaken, or even when it shows that they are significantly mistaken. Rather, what’s bad is if science shows that folk theories are — as Brian puts it — radically mistaken, like as in reference-failure mistaken. Learning that our mindreading faculties systematically overattribute our own beliefs to others’ minds is a welcome discovery. “Learning” that there are no beliefs or minds at all would be the bad thing.

  4. I wonder why you think of the epistemic contextualism is “broadly subjectivist”. I would have thought it fell more into the second category: knowledge is a state to be treated functionally, like belief or free action. The philosopher is bringing out the analytic connections that let us see how it fits in. Of course, it’s complicated by the context dependence Lewis claims the language of knowledge claims has: but again that’s not such a disanalogy from the language of propositional attitude ascriptions, which Lewis also indicates is messy in myriad ways, presumably sorted out in practice to some extent by contextual perameters, though I’m speculating even more with this last supposition.

  5. Daniel,

    I suppose I think that for knowledge the contextual elements are more important than the more traditionally speaking epistemic elements. It’s something of a judgment call, but what’s driving this is that I don’t think Lewis regards knowledge as an important philosophical concept. The notion of belief itself plays an important role in Lewis’s theories, above and beyond what we say about belief ascriptions. The notion of knowledge does not I think. Or, to put things another way, Lewis seems like he treats belief as a much more natural relation than knowledge. There’s not a great amount of textual evidence to back this up, just a gut feeling that Lewis doesn’t think there’s anything much more to say about theory of knowledge (or justification for that matter) than explaining the subjectivity of our knowledge ascriptions.

  6. So, nobody has thought to challenge the idea that it’s worse to overturn science with philosophy than to overturn common sense with science?

    Read John McDowell very carefully and then argue explicitly for that assumption.


  7. Would you care to argue for it yourself? Or would you rather just leave anonymous comments and then ask other people to do the work for you?

    It would also be nice to have a good long list of the times that people trying to overturn science with philosophy have ended up pointing us towards the truth. Or even a short list. Just a list would do. Or in the alternative a decent reason why such a list hasn’t been drawn up. You know, something other than an anonymous comment.


  8. Quote,

    “Second, we could say that common sense shows that science is either wrong or, at the very least, incomplete. Various forms of dualism and idealism lie this way.”

    I am not sure if you mean metaphysical or epistemological “idealism” here. If it is the latter, then your characterization does not seem like a very fair characterization of the idealist, as opposed to the realist, positions vis-a-vis truth and knowledge.

    Presumably, realists don’t think current science is complete. What makes someone an epistemological idealist, at least in my jargon, is that they go one step further and believe that, broadly speaking, the concept of a true statement is distinct from the concept of a statement that accurately and timelessly describes a mind and language independent world (maybe the negation of this is not a fair characterization of the realist position. So it goes). Consequently, the idealist just believes that there is no endgame for science—no notional set of propositions that pick out “all the physical the facts.” This can be a very weak thesis, implying no more than that, even if there is progress in natural science towards an asymptote of perfectly consistent and comprehensive propositional knowledge, natural science will never get there.

    Traditionally, the metaphysical idealists and dualists, or at least the good ones, did not see themselves as trying to revise or complete science, just assess and interpret its presuppositions. Aristotle began with the empirical and tried to use his “first philosophy” to show its deeper metaphysical and epistemological ground, likewise Leibniz and Berkeley. Descartes’ project was ultimately to develop a metaphysics and epistemology that could put common sense on a surer footing. Kant, famously, tried to deduce the truth of Euclid and Newton from the structure of the understanding. When he worried about science, it was because it did not seem to leave room for human agency (hence the positing of two worlds and the writing of endlessly opaque German prose). Frege called his logic “not laws of nature, but the laws of the laws of nature”(or something like that).

    In other words, I think the 4 options you have outlined have only begun to scratch the surface of how to approach the issue of the relation between common sense, science, and philosophy. It seems more fruitful to me to analyze what the possibilities are, rather than stick labels like “naturalist,” “idealist,” “realist,” and “dualist” on them (advice I have conspicuously avoided taking in this comment).

    [Note: I do not have much to say about Lewis because his most significant contributions seem to be in areas that I do not have the technical competence to assess.]

  9. I think it’s a very uncharitable (to say the least) interpretation of the claim “Various forms of dualism and idealism lie this way” to read it as saying all forms of idealism follow this pattern. Since some idealists clearly do want to overturn the scientific view of the world, I think what I said is uncontentiously true.

    I thought that the four views I put forward were more or less exhaustive – you either think science and common sense are compatible or they are not, and in either case you either take science to be primary or common sense. Maybe there is some middle ground I’ve left out here, but I’m really not sure what it is. Perhaps that there’s a version of compatibilism that says neither needs to defer to the other?

  10. “Since some idealists clearly do want to overturn the scientific view of the world, I think what I said is uncontentiously true.”

    Fair enough, I guess that since I have more than average sympathy with the “good” dualists and idealists, I tend to pretend that the bad ones—you know, the majority of American citizens—simply just don’t count.

    Now, as for your concluding question, I think part of the problem is the ambiguity in “common sense.” It seems like common sense to me that things like rationality, intentionality, the self, free will, phenomenal consciousness, and values can’t be fully naturalized (where “naturalized” means fully reducible to computational functions and physical structures).

    However, I also don’t think there’s anything wrong with naturalistic psychology, linguistics, or any other science: I just think they will probably fail to completely capture the things that make humans unique in their net. Ultimately, that’s just an empirical claim, but I think there is a reflexivity problem when we try to deploy our means for understanding the world on the means of understanding itself. Douglas Hofstadter gave a great lecture this semester at Tufts on “what’s it like to be a strange loop” that kind of captured the open-endedness of these problems. My worry is that when philosophers see failure in solving them they head straight towards full-scale eliminativism, which I can’t get around seeing as a prima facie incoherent position (i.e., I don’t know what the Churchlands’ claims are, if not statements of what they believe, and I’ve got no better word than “qualia” for what it feels like to wake up in the morning).

    So I guess I like your last option: common sense and science should, when clearly incommensurable, simply live happy and separate lives (that is, as long as it’s my common sense that gets to count as common sense!).

  11. The object of philosophy is to consider the incalculable. What science can measure it will, and what it cannot weigh is philosophy. You might say all humanities lead to philosophy, and science leads away.

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