So-called objectivist philosophy, but more generally any philosophy that claims to constitute an objective ontology, rests in part on a claim to have settled the is-ought problem. Hume's guillotine as it is sometime called, puts forward the premise that one cannot move from an observation of what one believes exists, or is, to what one ought to do. What this premise basically says is that experience of the world cannot proscribe actions to us. In other words, even if we know what is, we don't necessarily therefore know what ought to be. Since Hume, this has been one of the central problems of all Western philosophy and I believe in some sense that the failure to find a way through this is the reason that one of the very strong currents of philosophy fell into a fairly relativistic strain that we associate with writers like Lyotard and Derrida. 

And I must admit that when talking philosophy I find it difficult to imagine any serious way that an objective philosophy can be constituted. Despite simplistic claims to common sense philosophy or the so-called objectivism of people like Ayn Rand and her followers, I see no way to settle the is-ought problem. Some form of 'value-pluralism' as explained by Isaiah Berlin certainly makes a lot more sense to me. 

More on this tomorrow.