Chalmers also challenges the idea that facts provide a firm and reliable foundation for scientific knowledge. This argument falls in line with the other arguments.
Further difficulties concerning the reliability of the observational basis of science arise from some of the ways in which judgments about the adequacy of observation statements draw on presupposed knowledge in a way that renders those judgments fallible.1
Chalmers uses the example of Aristotle’s idea that fire is a substance. Fire was observed, and it could be seen rising into the air so that it seemed accurate to say that fire ascends. This was backed up by empirical data of seeing fires rising over and over again wherever instances of them occurred. This idea of fire being a substance was adhered to until chemistry debunked it. The problem in this example, according to Chalmers, is that the knowledge of fire as a substance was faulty and so the observations of fire rising were also faulty since they were based upon this knowledge. Chalmers also presents the example of the earth being observed to be stationary, and Venus and Mars being thought to not change size throughout a year.2 Both the facts and the knowledge in these examples are fallible, so the facts cannot be given credit for providing a firm and reliable foundation for scientific knowledge.
One difficulty concerns the extent to which perceptions are influenced by the background and expectations of the observer, so that what appears to be an observable fact for one need not be for another. The second source of difficulty stems from the extent to which judgments about the truth of observation statements depend on what is already known or assumed, thus rendering the observable facts as fallible as the presuppositions underlying them. Both kinds of difficulty suggest that maybe the observable basis for science is not as straightforward and secure as is widely and traditionally supposed.3
With this, Chalmers undermines three common views expressed regarding facts and how our scientific knowledge relates to them.
1. A.F. Chalmers. What is this thing called Science? 3rd Edition. Hackett Publishing Company Inc. Indianapolis/Cambridge. 1999. Pg. 15.
2. Ibid. Pg. 16-17.
3. Ibid. Pg. 17-18.