Duhem on Physical Theory and Experiment

Let's see if this works. It should come out as a slide show.
Duhem on Physical Theory and Experiment


which outlines Pierre Duhem's takedown of falsification and positivism. 



Modus tollens states that

1. p→q
2. not-q
3. /.: not-p

which  is to say "p" has been "falsified." However, in this manner, heliocentrism, natural selection, and electromagnetism were "falsified." Does Popper have the grace to blush?

1. heliocentrism→visible stellar parallax
2. no observed stellar parallax
3. /.: no heliocentrism

The others were similarly falsified. A new trait would be diluted before it could establish itself; permanent magnets did not have an electrical current.

But in every case, what was falsified was not the main proposition, but certain auxiliary assumptions associated with it. Heliocentrism would result in visible parallax IF the stars were close enough. Stellar distance was based on the brightness and apparent diameters of the stars; but those diameters were spurious: artifacts caused by optical aberration. The stars were really much farther away and the resulting parallax was too small to detect at the time.

Similarly, inheritance was not through the mingling of blood, as Darwin and his contemporaries thought, but through genes. That is, inheritance is digital,  not analog. A gene mutation could spread through a population until it reached a critical concentration and bearers began mating with one another. And the electron bore the electrical charge for permanent magnets.

IOW, the logical situation is:

1. p1+p2+...+pn→q
2. not-q
3. /.: not-p1 OR not-p2 OR... not-pn

All of which makes the verification or falsification of scientific theories rather more complex than many suppose. The electron was a leap of faith, postulated specifically to justify electromagnetism for magnets that were not overtly electrical. Hertz and the rest kept the Maxwellian faith. So also did Kepler and Darwin maintain that the facts were wrong, not the theory!

Consider the SF possibilities.