Scientific knowledge changes. In the past, there were different theories and ideas than now. In the future, there will probably be different theories and ideas that may or may not resemble the current ones. In the previous post (here), I noted that this makes it rather difficult to tell what theories there will be in the future. We are prisoners of the current knowledge and, as long as we do not actually have (justified) alternative theories and ideas, it is impossible to tell what alternatives are accepted in the future.
We have also noted, in a previous post (here) how Luca Tambolo (2020) pointed out that “In order to be plausible, the outcomes of counterfactual histories need to be appropriately continuous with [the] results [of actual science], which provide the yardstick for the assessment of the plausibility of counterfactuals” (2113). “What [–] we view as a plausible alternative to actual history of science is influenced by our currently accepted knowledge” (2123).
These problems share an essential feature: Interesting future and counterfactual (past) scenarios concerning the development of science are the ones where an idea or theory is accepted only if it is justified. Given this and given that the current theories are accepted because they are better justified than known alternative theories, we cannot write interesting future or counterfactual scenarios without using our current ideas and theories to tell which alternatives could be justified. Current ideas and theories leak into interesting scenarios.
This implies that no matter how much we want to challenge the present order in science by writing counterfactual histories, the task can never be epistemically robust. Of course, it is possible to write histories where different evidence is found because different theories were at the table, but imagined evidence is not actual evidence. Of course, it is possible to look at the history in order to find blind spots and dubious turns in theory-choice, but this can only establish problems in the justification of the current theories and ideas. Of course, it is possible to show historically that there are, in fact, evidential considerations that we have missed that confirm some alternative theory, but this would be a scientific breakthrough. However, a mere future or counterfactual scenario cannot establish that alternative science could be accepted (due to a great amount of justification that it could have received).
To challenge the present order of science, one may look at counterfactual historical developments. However, in order to justify the counterfactual histories, one must already change the present order of things. The value of counterfactual histories cannot lie in their ability to establish alternative science. However, counterfactual scenarios can still tell us many things about the structure of scientific development. Moreover, the mere fact that we cannot escape the present science epistemically speaking does not mean that it is an inevitable endpoint of history. On the contrary, we need to appreciate the fact that present science leaks into what-if scenarios. Due to this flaw in our epistemic predicament, our inability to tell how history could have developed otherwise does not tell us much about the history itself. Rather, it tells us the limits of the historiography of science.
Chang, Hasok (2004). Inventing Temperature: Measurement and Scientific Progress.
Tambolo, Luca (2020). So close no matter how far: counterfactuals in history of science and the inevitability/contingency controversy. Synthese 197 (5):2111-2141.
 Hason Chang’s idea of complementary science falls to the latter two categories. It has the explicit goal of contributing to the epistemic soundness of the current science (2004, 3).