Jack is getting pretty frayed and starting to act erratically, but I can't blame him either. Locke has acted like a nut job pretty much the whole time. Highly unpredictable and often dangerous.
What bothers me about both of the knuckleheads is that they can't ever discuss anything or compromise, let alone lay out all the information they have and let people make up their own dang minds. Is it really that hard?