My comments and questions:

“If pigs can fly, then phlogiston causes fire.” This statement is vacuously true. If Sorenson is correct, all claims/theories in science which depend on idealizations are similarly vacuously true since the antecendent is false. Now Sorensen says at 42-43 minute mark that there has to be some “premises” which are added to render certain claims/theories less accurate or correct. But this is not clear and it seems to me to be a little too imprecise to make much sense of his supposition theory.

In any case, I suspect it will not appease realists and may be ammunition for the instrumentalist and other anti-realists that all theories, true or otherwise (under more intuitive notions of scientific truth which seems to be about the world and which are true or false simpliciter and not true under logical material implication with an added false supposition as antecendent), in science or otherwise are similarly vacuously true even if they happen to be less or more accurate, etc, under some premise. In this way, no theory is really true in a more robust sense required by the realist because they will always be vacuously true under some (false) idealization.

What I am missing from Sorensen’s account here?

Sorensen has responded to my question and comment. A passage from his response:

ReplyDelete"If P then Q.

P is close to the truth.

Therefore, Q is close to the truth.

Illustration: If the earth is sphere, then its surface area is 4pi times the square of the earth’s radius. `The earth is a sphere’ is close to the truth. Therefore, the surface area of the earth is 4pi times the square of its radius.

This type of reasoning is inductively strong because a little difference rarely makes a significant difference. With threshold phenomena, some little difference may make a big difference (such as an avalanche). So background knowledge is needed to assess the applicability of the vacuous conditional.

Standards also matter. For some purposes, we will need more accuracy and so need to accommodate the fact that the earth’s spin makes it bulge in the middle. But we can deal with this with another round of idealization; suppose that the earth is an oblate sphere . . . .

Even if we view a theory as a conjunction of assertions, the scientific realist is entitled to use suppositional reasoning in applying these assertions. For the realist is entitled to classical logic and that legitimates both reductio ad absurdum and conditional proof."

This more detailed idea seems to me to be a more plausible account of the supposition theory.