Mrrzy, I guess it depends on what you mean. We don't really know if alien life exists although we suspect it to. But is that really knowing we don't know something? I mean we understand and know the concept of alien life, we just have no idea if it exists in fact, or what form it might take and so on.

But there are probably concepts that no-one has thought of yet, however we can't know this either for sure. If we think of a concept it is no longer entirely in the realm of the unknown, however little information we might have about it.

Joe, I think what you're saying is along the lines of that old Oxford / Cambridge scholar's saying "the more I know the more I realise I don't know". In order to know whether absolute knowledge is attainable, we'd have to know if it it exists to begin with. Empirically we don't have that information yet. Religiously we know such knowledge does exist, since God has it (He is omniscient, right?) God is omniscient by virtue of being God. In order to have an equal grasp of knowledge we'd have to become God, or like God (which if memory serves me, was part of the idea behind eating the apple in Eden). My religious understanding is that we cannot become God, though we can aspire to imitate some of His virtues.

But that's another story. Absoulute truths are attainable, and do exist. I emphasise the plural in order to mean not some great unifying truth but rather lots of things that are true.

For instance, there are logical truths. One that springs to mind is the phrase sometimes quoted to me by people I know that "there is no such thing as absolute truth".

But that statement is an absoulte in itself. Now it is either true of false. If it is false, then clearly some absolute truth does exist. If it is 'true' then it contradicts itself as an absolute, and so absolute truth exists, by implying it itself, cannot be true.

Therefore it is true that truth exists. That's a kind of absoulte truth which we can know.

Take the example of various scientists and thinkers over the years. Einstein didn't completely reject the theory of gravity formulated by Newton. The theory of relativity didn't make the truth that gravity exists untrue, rather, the new discoveries refined what we understood about the previously realised truth. Maybe that's similar to what you say about learning more along the path as we go.