The issue which I am interested in concerns his characterization of physics (and chemistry) as sciences which want to establish eternal, universal laws of nature, as opposed to biology, geology, astronomy, which contain arbitrary elements as well which can only be explained by historical means. The way evolution took place, the way the earth devolped, the way our solar system or the milky way developed, all this was not determined by natural laws only. Explanations in these subject cannot be reduced to physical laws only, but also depend on certain conditions which have no explanations. Explaining the theory of evolution in terms of genetics, genetics in terms of chemistry, and chemistry in terms of physics will not explain why there are humans, or even why there are animals at all.
However, Weinberg even admitts that there might be historical factors in physical theory as well. He writes:
"It is not clear whether universal and the historical elements in our science will remain forever distinct." (p. 34)This is an interesting twist: maybe, not only the fact that all planets go around the sun in the same direction is also a matter of history, but also the values of certain parameters in the standard model:
“Not only is it possible that what we now regard as arbitrary initial conditions may ultimately be deduced from universal laws – it is also conversely possible that principles that we now regard as universal laws will eventually turn out to represent historical accidents.” (p. 38)He continues illustrating the idea of multiverses and subuniverses, which I will touch at another occasion. Nevertheless, he claims, this will not detain us being able one day to find a final theory:
“The most extreme hope for science is that we will be able to trace the explanations of all natural phenomena to final laws and historical accidents.” (p. 37)After having read this chapter "on a piece of chalk", I again felt reminded strongly on the idea that there might somehow be no difference between physical laws and historical accidents. There might be a viewpoint from which all laws are accidential, and another viewpoint from which nothing is accidential and everything lawlike. What goes wrong here is maybe that it is notoriously difficult to exemplify the notion of regularity, which underlies the notion of a natural law. We con only observe the former, never the latter. What I actually want to get into is not the problem of induction itself, but what it has to do with the dichotomy between theory and observation. But more on this problem next time.
