Let me add a few remarks, not to disagree with Charles Taliaferro, but to help bring the discussion back to earth after wondering about zombies, etc! I understand quite a bit about my friend Jack's political point of view (we argue often enough in the pub); but I've little idea where he is coming from sexually (what clues I have seem to have no pattern, and a few drunken chats have left me even more mystified). My colleague Jill shares my tastes in music, and we seem to enjoy much the the same concerts and CDs for the same reasons -- when we talk about them, sometimes at length, we seem to be very much on the same wavelength; but in some other respects she's a closed book to me, and the more we discuss, the less I feel that I am "getting" her. And isn't that how it ordinarily is (when we use "understand" in the ordinary way, not in some fanciful philosopher's sense)? We might understand someone's take on X very well, find it difficult to get on their wavelength on Y but sort-of understand, and...

Isn't it just that typically not much hangs on answers about the numbers of stars, but you can e.g. ruin your clothes by getting it wrong about the paint? But if it matters (say, to win a competition with a big cash prize), I bet you would double check my statement about the number of stars, and not just fill in what I tell you on the competition entry form. And if we are idly gossiping in the pub, and I boringly mention that the new-fangled paint that they've been advertising takes for ever to dry, I don't suppose you'd leap out of your seat to check the room I've been decorating: you'd shrug and say it was my turn to buy a round of drinks. What you bother to check will depend not on the topic so much as on how much hangs on getting things right.

As I've noted here before , we should surely distinguish loving someone from being in love with them. I might delight in the "sheer goodness and well being of" my daughter, miss her presence, especially when I'm feeling low -- that's evidence of love, but not of being in love. It is only too easy to be in love with someone you don't really love in Charles's sense (which is why I don't think his reply will do as an answer to a question about being in love). You can be obsessed, lustful, unable to get the other person out of your mind, your heart leaps at their glance, you are wildly jealous of glances bestowed elsewhere, but for all that you don't really care for the other in the right way, or delight in their well-being etc. ("If you really loved her", we might have to say to the man in love, "you wouldn't treat her like that.") Being in love, as Romeo memorably says, can be a "madness ... a choking gall and a preserving sweet". Proust is depressingly good on this!

It isn't right to say that Christianity, per se, advocates a god that values what you might call blind faith, i.e. faith which is not grounded in reasoned argument. Perhaps that's true of some sects, but certainly not all. Catholic tradition has it that the existence of God is rationally demonstrable (and that God wants us to use the reason that we have been endowed with). So those atheist critics who argue that the supposed arguments for God don't work -- whether purely a priori arguments or partially empirically based arguments -- aren't point-missing, but are directly engaging with a major strand of Christian thought which holds that there are rationally compelling arguments for his existence. But suppose you do posit some god that goes out of its way to hide itself and give no rational evidence for its existence (even though it wants us to be credulous and believe in it). Then to be sure, the empirical state of the world is the same whether or not such a being exist. By hypothesis, we have no...

If you want to try something rather more accessible than the heavy-duty books that Eric Silverman suggests, then try Richard Dawkins The God Delusion . Sure, it's shallow in places, and a bit crass in others, but it will certainly be an enjoyable read that gets you thinking hard.

It is a requirement for something to be genuinely known to be true that it is true. So knowledge implies truth (in the sense that if X knows that so-and-so, then it is the case that so-and-so). But that doesn't make knowledge the same as truth. The implication the other way around doesn't hold. There are truths that you don't know, that I don't know, and indeed that no one right now knows (maybe because nobody has bothered to find them out, maybe because the time has past when anyone could check, or because the truths are about far-off events like meteorite strikes on the far side of the moon, or for other kinds of reason). Leaving ominiscient deities out of it, not every truth is known. But we might wonder whether every truth is knowable , in principle, e.g. by a suitably placed and sufficiently smart observer. The trouble with that idea is in spelling out the "in principle".

It's worth saying something first about Descartes (as it wasn't his view that he couldn't prove he wasn't dreaming). Descartes is troubled that, as he sees it, the then dominant systematic story of the world is in deep error, and is getting in the way of the growth of the revolutionary new science of the day. He has a diagnosis, too, of the source of error -- he sees Aristotelianism as springing from some deeply embedded childhood habits of thought. Radical measures are required to prise us out of such deep-rooted error. The ‘Method of Doubt’ provides the once-in-a-lifetime jolt needed to shift us out of certain childish thought-habits and to get us adopt better intellectual methods and open the way to improved science. Faced with even the most reasonable-seeming presumptions, Descartes suggests, "I must withhold my assent from these former beliefs just as carefully as I would from obvious falsehoods, if I want to discover any certainty in the sciences." So for Descartes, it is not that our...

One thing I know is the difference between the taste of sangiovese and pinot nero -- a bit of wine-wisdom I've acquired over the years. But I certainly would be very hard put to express that knowledge in propositional form, at least in any informative way that could usefully convey my knowledge to you. Is there any proposition I could use to do that? Of course, I can say -- taking a sip -- " this one is sangiovese", and -- taking another sip -- " that one is pinot nero". But that won't help you, unless you are sipping away from the same wines, and you are attending to the differences. You need to experience the wines for yourself, and need to pay attention to them and learn to tell them apart. And developing that skill, that know- how , seems to require something other than picking up propositional knowledge- that about the wines.

The idea of a "disembodied spirit" is hardly a clear one. And no doubt some ways of trying to fill out this idea lapse into sheer incoherence. Understood in such a way, there just can't be any such things as "disembodied spirits". And non-existent beings can't do any causing! But let's suppose we can spell out an internally coherent theory that purports to explain various occurrences by postulating the existence of things that, by the lights of our current scientific beliefs, do look decidedly ghostly. Well, it could in principle turn out that, by our best standards of theory assessment, this surprising theory in the end trumped rival theories. Why not? After all, similar things have happened often enough in the history of science -- meaning that initially whacky looking theories postulating weirdly spooky stuff (action at a distance! photons going through both slits!! many-dimensional strings?!?) can begin, given enough successes, to look to be the best game in town, and even come to be firmly...

I am entirely certain that two and two is four, that the earth is bigger than a peanut, and that Hitler didn't win World War II. Aren't you?