Topic Summary: Although I am not an infallibilist, I disagree with Popper about how common it is for true theories to later be proven false. This is because I disagree with him about what a theory is, or what a universal proposition means.
Goal: Become a better philosopher. More specifically, I think that much of Popper’s philosophy—and my disagreements with it—hinges on this topic (and some things closely related to it).
CF relevance: I assume that CF agrees with Popper on this point.
Do you want unbounded criticism? (A criticism is a reason that an idea decisively fails at a goal. Criticism can be about anything relevant to goal success, including methods, meta, context or tangents. If you think a line of discussion isn’t worth focusing attention on, that is a disagreement with the person who posted it, which can be discussed.) Yes.
(All Popper quotes are from Conjectural Knowledge: My Solution to the Problem of Induction).
Popper thinks that Newton’s theory might be false, because he thinks it contradicts the theory of Einstein.
I first turned against [the idea that not all the general propositions of science are mere hypotheses] because of Einstein’s theory of gravity: there never was a theory as well ‘established’ as Newton’s, and it is unlikely that there ever will be one; but whatever one may think about the status of Einstein’s theory, it certainly taught us to look at Newton’s as a ‘mere’ hypothesis or conjecture.
I don’t agree that Newton’s theory contradicts Einstein’s, but talking about Newton’s vs Einstein’s theory is a complicated discussion.
Thankfully, Popper gives some much simpler examples of established laws that he thinks have been refuted in the sense that they were originally meant. One example he gives is
(c) that bread nourishes,
in whatever sense Hume meant (c) when he wrote it. (c) is false, says Popper, because it
was refuted when people eating their daily bread died of ergotism, as happened in a catastrophic case in a French village not very long ago. Of course (c) originally meant that bread properly baked from flour properly prepared from wheat or corn, sown and harvested according to old-established practice, would nourish people rather than poison them. But they were poisoned.
It is bizzare to me that Popper thinks Hume’s common sense theory that “bread nourishes” is false. I think Popper is imagining that “that bread nourishes” is shorthand for some very formal statement, in the vein of analytic philosophy, which says something like “for any bread which exists in the set of all logically possible bread, if it satisfies conditions C1, C2, C3, C4, and C5, then it will always nourish in all circumstances.” I don’t even think that such statements are meaningful (I don’t believe in “logically possible”). But regardless, I think that this isn’t what people actually mean when they say “bread nourishes.”
What do I think it means that “bread nourishes”?
It means that bread, in essence, does nourish people. When it doesn’t nourish, that state of affairs is caused by some existent which is not essential to the nature of bread itself (the Claviceps purpurea fungus in the case of the ergotism), or some existent which is not essential to the nature of man himself. For example, bread will not nourish if it is laced with arsenic, and people who have celiac disease will not be nourished by bread.
What is an essence? Here I take Ayn Rand’s definition (ITOE)
Objectivism holds that the essence of a concept is that fundamental characteristic(s) of its units on which the greatest number of other characteristics depend, and which distinguishes these units from all other existents within the field of man’s knowledge.
In the case of bread, one of its essential characteristics is that it is a foodstuff for man. Many or most of its other characteristics depend on that. Indeed, that’s why bread has the size and shape that it has, that’s why it’s easy to chew, that’s why it’s made of flour, that’s why you can buy it at the grocery store, etc.