I've had as good a time as anyone else discussing armchair philosophy based on cosmology and human nature, but now take the position that it would be professional negligence to engage in same without a firm grounding in e.g. particle physics and evolutionary biology. Other than a Dan Dennett (on evolutionary bio side), who are some contemporary philosophers who are exploring this space? For example, I would love to read the extent to which Aristotle survives or thrives in the light of scientific discoveries over the intervening millenia.

I agree that philosophers should engage with relevant science. But of course, what science (if any) is relevant depends very much on what philosophical questions you are tangling with. If you are concerned with the metaphysics of time, for example, then you'll no doubt want to know something of what various kinds of physicist doing foundational work on relativity, etc., are thinking (but you needn't care at all about e.g. neuroscience). If you are concerned with the philosophy of mind then you'll probably want to know something of neuroscience and experimental psychology (but you won't care about cosmology). If you are interested in whether numbers are objects in Frege's sense, or under what circumstances abortion is permissable, or in how names latch on to the world, or whether a non-minimal state is justified, you won't care much about either neuroscienc e or cosmology, or about evolutionary biology either. So what science, if any, you need a "firm grounding" in as a philosopher will...

According to Karl Popper, a hypothesis is scientific if it can be observationally falsified, not, if it can be verified. One instance not in accordance with a supposed law refutes the law, but many instances in conformity with the law still do not prove it. Accepting this falsification test, we may remark that the idea of the divine existence either could, or could not, be falsified by a conceivable way of observation. If it could not, then science in no position to test theism. Please comment. Thanks

I'm not as confident as Peter Fosl about the testability issue: perhaps we need to know a bit more about what counts as " the theistic hypothesis". After all, a lot of theistic hypotheses look perfectly testable by ordinary scientific standards. Take, for example, the claim that Zeus exists. I take it that no one now reading this site believes that that claim is literally true! But why? Well the existence claim, taken literally, is bound up with a range of stories about how the world works; and we now know the world just doesn't work that way. Mount Olympus is not populated with gods; bolts of lightning are naturally caused discharges of electricity; clouds and rain are not gathered by supernatural agency; burnt sacrifices to Zeus do not increase the chances of better crops or victory in battle; and so it goes. Science -- in the broadest sense of our empirically disciplined enquiries into how things work -- has shown we have no need of the Olympian gods to explain anything. Of course, that...

If I make a claim, based on empirical evidence, that itself invokes the existence of unobservable entities (e.g., those which are very small) am I making a supernatural claim? For example, if I claim that there are tiny elephants which act as the smallest building blocks of all that exists, is this supernatural or is it simply a scientific claim, given that we currently do not possess the means to observe existence at this level but we might eventually develop such means?

If you have a powerful theory about the smallest building blocks of the world, aboutwhat the laws governing them are, how they combine to generate morefamiliar entities, and this allows you to make more or less successful predictions about the world, then you are presumably giving a scientific account of the natural world. What else? True, these building blocks may not be directly observable, and indeed yourtheory may explain why they can't be observed. But postulating theirexistence may still be the best explanatory game in town by standardscientific criteria. There's nothing 'supernatural' going on -- even if the quantum mechanical laws governing these micro things do make them pretty weird by everyday standards. You jokingly call these ultimate building-blocks "elephants", I call them "quarks" (in fact a name that seems to have originated in another joke). But what's in a word?

Why does mathematics "work"? How does it manage to describe the physical world?

Which mathematics manages to describe the physical world? Mathematicians offer us, e.g., Euclidean and non-Euclidean geometries of spaces of various dimensions (and the non-Euclidean geometries come in different brands). They can't all correctly describe the world, since they say different things even about such simple matters as the sum of the angles of a three-dimensional triangle. But we hope that one such geometry does indeed describe the sort of structure exemplified by physical space (or better, physical space-time). That's pretty typical. Mathematicians explore all kinds of different possible structures. Only some of them are physically exemplified. For example, group theories explore patterns of symmetries; some of the patterns are to be found in the world -- but I guess that no one thinks e.g. that the Monster Group is physically instantiated. Mathematical physicists tell us which kinds of structures are to be found in the physical world and then use the appropriate mathematics to...

I would appreciate some recommendations on texts (for a layperson -- a nonprofessional philosopher) whose subject is the philosophy of science.

I'd start with some more modern books actually written for beginners, before tackling Popper, Nagel et al. Two that in my experience work well with students are Alan Chalmers' What is This Thing Called Science , and Alexander Bird's Philosophy of Science .

Scientists often say (rather diplomatically, I think) that science cannot rule on the question of whether God exists. But is this really true? I suppose that some people might hold God's existence to be evident a priori; but I don't think that most religious people actually think this way.

Discussions of the status of theological claims can suffer from a restricted diet of examples. It is worth remembering that lots of theological claims are in fact uncontroversially true or uncontroversially false, and their epistemic status (and their relation to science) is pretty clear. Take, for example, the claim that Zeus exists. I take it that no one now reading this site believes that that theological claim is literally true! But why? Not, I'm sure, on the basis of fancy philosophical arguments. Yet rejecting the existence of Zeus surely isn't irrational prejudice either. For the existence claim is bound up with a range of stories about how the world works; and we now know the world just doesn't work that way. Mount Olympus is not populated with gods; bolts of lightning are naturally caused discharges of electricity; clouds and rain are not gathered by supernatural agency; burnt sacrifices to Zeus do not increase the chances of better crops or victory in battle; and so it goes....

Two questions. It seems that no one has figured out good standards for acceptance or rejection of philosophical arguments. In science, observation is king. If evidence contradicts a theory under careful conditions, the theory is false. In math, we justify things formally; we cannot expect more certainty. So would you agree that philosophy, as a field that aims at knowledge and not something else like evoking emotions, suffers from a lack of standards? And since at the moment I suspect it does, I want to ask also, why do philosophers act so certain? To them their arguments are true or correct (or whatever) without empirical evidence or rigorous proof. They should be the most uncertain people of all, even more so than scientists. And they are pretty darn humble. (A better way to ask this might be, aren't proof and evidence the two best ways to knowledge? If so, shouldn't philosophers be much more uncertain than they appear (to me)? I now realize it's dependent on how I see things, so I only hope you can...

Just a footnote to Marc Lange's response (which seems spot on to me). It is worth adding that in serious analytical philosophy there is actually a good deal more agreement on arguments than there might appear to be at first sight, and there is a good deal of pretty secure knowledge. For what often emerges from the to and fro of debate is essentially something of the form "If you accept A, B and C, then you'd better accept D too". Then one party might endorse A, B and C and conclude that D; and another party might think D is unacceptable, and conclude that one of A, B, or C must be wrong. And another party again (me, often!) might not know how to respond. [A trite example. If you accept act utilitarianism plus some other things, it seems that you should sanction the sheriff hanging an innocent man if that is the way to stop a riot in which more innocent people are killed. Some bite the bullett, some think so much the worse for utilitarianism.] Now, there may indeed be a loud disagreement between...

Let's say that by positing the existence of some unobservable entities (e.g., strings), we can form theories which reliably predict observable behavior. Does the success of such theories provide evidence that the posited entities actually EXIST? Or is the significance of such entities merely heuristic?

Ian Hacking, in his very readable book Representing and Intervening , describes an experiment done by a friend which involved changing the electrical charge on a minuscule ball of niobium. And how was that done, he asked? His friend said "Well, we spray it with positrons to increase the charge or with electrons to decrease the charge". And Hacking comments "From that that day forth, I've been a scientific realist. So far as I'm concerned, if you can spray them then they are real ." Hacking's story remind us that many of our best theories about "unobservables" enable us to do a lot more than reliably predict observable behaviour in a hands-off, watching-from-the-sidelines, sort of way. They do more than merely tell us a story about a supposed hidden substructure of the world, something that we could perhaps treat as a "just so" story, a useful fiction, a "heuristic". Our theories guide us in causally manipulating unobservables, and in causally producing desired observable effects. We can...

Is science merely a system of universally codified opinion? Cf. Jacob Klein, Paul Feyerabend, etc.

At any one time, quite a bit of science is provisional, conjectural, and the subject of hot debate among scientists. So, rather boringly, science in general can't be said to be a system of " universally codified opinion". I suspect, however, that the intended question is something more like this. Take a scientific claim that isn't any longer provisional, conjectural and contested -- e.g. take the claim that DNA has a double-helix structure. Then, the rephrased question goes, does this claim in any good sense tell us the fact of the matter, tell us how the world is independently of us? Or is it, in the end, merely that some bunch of people (the scientists) have come to a shared opinion about the world, in this case the opinion that DNA has a double-helix structure? To which the common-sense realist answer is the first. After all, science tells us, it is the fact that DNA does indeed have a double-helix structure which causally explains the behaviour of DNA under...