I'd like to present the following as an example of what I see as the reciprocal relationship between claims and supporting data:
Instead of proposing "thought experiments" or "hypothetical questions", why don't they present the scientific data that supports their claims?
The discovery of Charon in 1978 showed the mass of Pluto to be much smaller than expected, and insufficient to explain the observed perturbations in the orbits of Neptune and Uranus (the calculated orbit of Neptune fit observations only for a few years, and then started to drift away, while the orbit for Uranus fit the observations during one revolution but not during the previous revolution). As a solution, the astronomer Tom van Flandern hypothesized the existence of a tenth planet beyond the orbit of Pluto. Over this past weekend, the news was released that this hypothesis was confirmed in 2003 with the discovery of a yet-unnamed planet about 3.6 billion miles from the Sun.
This was a repeat performance of a process of discovery that took place over 150 years ago when John Couch Adams and Urbain Leverrier hypothesized the existence of the planet we now know as Neptune. There were other proposed explanations for the discrepancies in the orbit of Uranus observed at that time. One hypothesis was that some time after Tobias Meyer's (assumed) sighting of that planet (earlier, in 1756), its orbit was altered by an impact from a large object. Other astronomers were so frustrated by their inability to explain Uranus's behavior that they were driven to considering the possibility that Newton's Law of Universal Gravitation somehow failed when applied over sufficiently large distances.
In my opinion, this willingness on the part of those scientists to question their most fundamental assumptions in the face of what they saw as sufficiently strong evidence stands in stark contrast to the stubbornness with which adherents to other systems of thought often cling to their most cherished notions, showing more willingess instead to perform the most agonizing mental contortions imaginable in the hope to sustain them.
We are talking about two separate things here: evidence, and interpretations of evidence; when John Paul says: "Hypothetical questions are not a valid way to do anything", he directs our attention to the latter rather than the former. Is this a valid concern? Absolutely. What possible value can evidence have if flawed methods are used to evaluate it? I believe, however, that he has underestimated the value of the asking of hypothetical questions such as: "Could Uranus's orbit have changed due to an impact?" as a tool toward formulating and evaluating interpretations.
Did the discovery of Neptune completely eliminate the possibility that Uranus had been hit by some object? No. Is there some evidence that could be used to estimate how reasonable a proposal that was? Yes. The liklihood of an impact by an object of the required size can be inferred from the frequency with which impacts by objects of varying sizes are observed to take place elsewhere in the solar system (infered in turn from the presence of the craters of varying sizes which they produce); the probability of such an event occurring in a given period of years could then be expressed as a percentage. In this case, the impact hypothesis would be very undesirable, because the narrow temporal window would make this percentage very low; however, it might still be considered the best explanation in the absence of better alternatives.
Did the discovery of Neptune completely eliminate the possibility that Newton's law fails over large distances? No. Newton's law rests an assumption which is one of the axioms of science: that consistency in phenomena we observe bespeaks a general underlying consistency to the universe at large. We have no choice but to assume that if galaxies exist which are too far distant for us to observe, that gravity operates the same there that it does here; that the laws of conservation will not suddenly begin to be suspended on alternate Wednesdays; etc. The 'flawed law' hypothesis would then be even less desirable than the 'impact' hypothesis because one of its implications is that a fundamental assumption (one in which we place the highest degree of confidence) is flawed.
Many creationists have learned from first-hand experience that fabricating evidence is a tactic on which they can not rely. One example recently mentioned in this forum, that of fossil tracks purported to show dinosaurs and man coexisting, has been so thoroughly debunked that leading creationists have been forced to admit the deception and now caution their followers not to use this example lest the effort serve only to further damage the credibility of creationism's proponents (this is hardly an isolated case, btw; those new to the debate would do well to have a look at the more comprehensive list found here):
Instead, the creationist community has gradually come to see the wisdom in taking a different approach, one more compatable with the standard practice of science: to focus on constructing alternative interpretations -- of the same evidence -- to those offered by evolutionary theory. I believe that scientists are not immune to certain human foibles and the pitfalls to which they often lead, among them: bias, bogus assumptions, hasty conclusions, optimistic projections from sparse data, and the like. Much of the discourse that takes place in science is therefore quite justifiably directed toward logical examinations of interpretations rather than to direct examination of evidence. Consider this snippet, part of a long (and occasionally, surprisingly ugly) debate between Richard Dawkins and Stephen Jay Gould:
"Richard is basically wrong, [about gene selection being the most meaningful level at which to consider the effects of selection] because organisms are doing the struggling out there. If organisms could be described as the additive accumulation of what their genes do, then you could say that organisms are representing the genes, but they're not. Organisms have hosts of emergent characteristics. In other words, genes interact in a nonlinear way. It is the interaction that defines the organism, and if those interactions, in a technical sense, are nonadditive -- that is, if you can't just say that it's this percent of this gene plus that percent of that gene -- then you cannot reduce the interaction to the gene. This is a technical philosophical point. As soon as you have emergent characteristics due to nonadditive interaction among lower-level entities, then you can't reduce to the lower-level entities, because the nonadditive features have emerged. These features don't exist until you get into the higher level. His argument is wrong. It's not just a question of being inadequate. It's wrong."
I feel that such dialogues -- by being directed to issues of bias and assumptions on the part of each participant's adversary -- demonstrate an implicit acknowledgement of the above-mentioned pitfalls already; but it may be that creationists have something to offer too, if only by virtue of, shall we say, a somewhat inhanced willingness to challenge science's most fundamental assumptions. This is something which scientists themselves are generally reluctant to do, but which creationists (proponents of the Young Earth model in particular) must be willing to do at every turn.
In my opinion, what we primarily do here is to consider interpretations of evidence. In fact, our debates are mostly over interpretations of interpretations -- I mean, how many here claim to be original theorists? How many of us are involved in hands-on collection of evidence either in the laboratory or in the field? How many claim original authorship of the first theoretical explanations of such findings? We are mostly debating the quality of ideas which have come to us second-hand, and most of us are struggling just to understand the arguments; never mind defending them.
I seriously doubt that history will render ironic this prediction: the world will little note nor long remember what we say here -- but to anyone who took the trouble to wade through this unintentionally lengthy post, I submit the following:
The formulation of a theory (an interpretation of evidence) depends not only on what one considers, but also -- and perhaps to a greater extent -- on something one may not take time to consider: those assumptions which are taken on board unexamined. When it comes to a willingess to examine one's own assumptions, I see the scientist and the creationist as being on approximately even ground. But the scientist's reasons for leaving his assumptions unchallenged are very different from the creationist's reasons for doing so. For the scientist, the questioning of his most fundamental assumptions (laws of gravity, of conservation of matter and energy, etc) is a last desperate resort, because discarding these, his strongest and most exhaustively tested tools, would leave him without any basis for formulating conclusions. For the creationist, questioning of his most fundamental assumptions is never an option, under any circumstances, because his fundamental assumptions are the very conclusions he has already reached.