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...

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 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?

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'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 .

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....

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...

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...

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...