The conclusions of scientists are based on evidence, and the evidence
remains for all to see. Scientists know that their ideas must stand
the scrutiny of other scientists, who may not share their
preconceptions. The best way to do this is to make the case strong
enough on the basis of the evidence so that preconceptions do not
matter. And scientists themselves condemn preconceptions when they see
them. (Stephen J. Gould, the most vocal recent crusader against
preconceptions in science, was vehemently anticreationism.)
The history of science is filled with scientists accepting ideas
contrary to their preconceptions. Examples include the reality of
extinctions, the reality of meteors, meteors as causes of mass
extinctions, ice ages, continental drift, transposons, bacteria as the
cause of ulcers, the nature of prions, and, of course, evolution
itself. Scientists are not immune to being sidetracked by their
preconceptions, but they ultimately go where the evidence leads.
Scientists make deliberate efforts to remove subjective influences from
their evaluation of conclusions; they do a good job, on the whole, of
reducing bias. They do such a good job, in fact, that what
creationists really object to is the fact that scientists do not
interpret evidence according to certain religious preconceptions.
The hypocrisy of this charge cannot be overstressed. Creationists
state outright that they accept only what they already assume.
Consider part of Answers in Genesis' Statement of Faith: "By
definition, no apparent, perceived or claimed evidence in any field,
including history and chronology, can be valid if it contradicts the
Scriptural record" (AIG n.d.). The Institute for Creation Research has
a similar statement of faith (ICR 2000). Creationists admit up front
that their preconceptions, in the form of religious convictions,
determine their conclusions.