Assertion 4.18: Macroevolution remains unproved because no one has observed it. In fact, macroevolution is in principle unobservable, so evolution is unscientific.
Analysis:
Although information in experimental science is acquired through observation, the observation of a great amount of indirect evidence of a process makes as good a scientific case as the direct observation of a process. As Michael Ruse asks, "[t]he evidence that I have a heart is all indirect, neither I nor anyone else ever seen it, but does anyone really believe that it is not a fact that I have a heart?" (Ruse 1982:58). In the same way, there is sufficient evidence for macroevolution that it can safely be considered a fact without direct observation of the process occurring in our time. We need not, as many unsophisticated creationists put it, observe cats changing into dogs right before our eyes, in order to have a good case for macroevolution.
References
Ruse M. 1982. Darwinism Defended: A Gudie to the Evolution Controversies. London: Addison-Wesley.