continuing with the epistemological musings

The modern approach to Habermas's First World, what he analogizes to the Platonic ideal of The True, is science. That's our word for how we come to understand intersubjective reality, the world we live in. As I suggested before, science can be analogized to a building. It rests on a foundation and each successive story rests on all that is beneath, until we get to the roof.

 

So, the scientific analogy to the foundation is physics, i.e. the study of the fundamental properties of the universe. Actually physicists are in something of a state of angst right now because the discipline seems to have two layers and it isn't clear how they work together. At bottom is the realm of the very small, the quantum world of particles and forces. It is basically understood how the apparently random events at the quantum level get aggregated to the more predictable larger scale world that we inhabit. 

 However, the macro level phenomena of acceleration and gravity (which are equivalent) and their relationship with time and space, as explained by Einstein's theory, does not emerge from the quantum world. That these theoretical realms have not been reconciled bothers physicists, although personally I don't see why the explanations for the two classes of phenomena couldn't just be different. We don't know where the universe comes from in the first place or why it is the way it is.

In any case, moving on come from the foundation we come to what we might call the foundation, which is chemistry. In principle it might be possible to derive all of chemistry from physics -- the interactions among atoms that create molecules can be explained and predicted by quantum theory -- but it isn't possible in practice. Certainly it would be very inefficient. Chemists experiment with atoms and molecules. It's much easier to learn the properties of atoms and molecules by means of experiment rather than trying to predict them from physics, and once you know them, you can make predictions about how they will further interact and test these by experiment as well. 

One way of saying this is that chemistry has emergent properties, that can be understood and manipulated at the level of chemistry without reference to physics. On the other hand, chemistry has to be consistent with physics -- these emergent properties cannot contradict what underlies them -- and physics can be of some help informing chemistry. 

Nevertheless physics and chemistry are different disciplines, requiring different inventories of knowledge and using different methods of discovery. This seldom causes Dunning-Kruger type problems because the difference is very clear and the findings in both fields are rarely disputable. In other words physicists wouldn't get very far if they tried to make inaccurate claims about chemistry, and vice versa. However, problems do crop up when we get to the next level, which is biology, and that's why Linus Pauling got into trouble. That's for next time.