Defender's Guide to Science and Creationism

Assertion: Theories about the past cannot be scientific, because the past cannot be observed.

Analysis

This kind of claim places overly strict limits on what counts as scientific. The claims suggests that a proposition about x cannot be scientific unless x is observable in the here and now. In actuality, however, this is not what scientists means when they talk about the importance of observability in science. What scientists mean is that the proposition in question must have observable consequences—in other words, that it must be testable by means of observation. Nothing about this requires that the entities referenced in the proposition be themselves observable. If this were not the case, then the proposition, for instance, that atoms exist would have been unscientific before the development of electron microscopes, since distinct atoms are too small to observe directly by less sophisticated means. But, of course, the proposition was scientific, because the existence of atoms had directly testable consequences.

Likewise, scientific theories about the past have testable consequences. Big Bang theory, for instance, makes a claim about the state of the universe 13.7 billion years in the past. Not only were there no observers back then, no observer could have existed under the conditions posited by the theory, so it seems that we have here a prime example of a theory discussing something itself unobservable. However, the truth of the theory has consequences that can be observed today: the expansion of the universe, the abundance of light elements, and the cosmic background radiation. If any of these predicted consequences failed to pan out, the theory would have to be scrapped or modified. The same considerations go for other scientific theories that make statements about the past, such as theories in geology and parts of evolutionary biology.

References

Ruse M. 1982. Darwinism Defended: A Guide to the Evolution Controversies. London: Addison-Wesley.

Defender's Guide to Science and Creationism
Copyright © 1997, 2012, Mark I. Vuletic. All rights reserved.