When the White House was asked for a comment about the Terry Schiavo autopsy results, Scott McClellan said:
"It doesn't change the position that the president took," said its spokesman, Scott McClellan. "The president believes we should stand on the side of defending and protecting life."
This is perfectly consistent with the way Republicans think about many of the issues.
The way rational people come to have a position on something is by looking at the facts and the evidence, and then coming to a conclusion. For this reason, if new evidence comes to light it is perfectly reasonable for a rational person to change his or her position.
Many republicans not only do not think like this, they actually scorn people who do. They call them flip-floppers. To many republicans considering new evidence is not a virtue, it is dangerous, it is almost blasphemous. This is because they did not come to their positions based on a careful consideration of the evidence, they came to them because it stemmed from their ideology. We can see this with Iraq (most clearly now from the Downing Street Memo), we can see this with Stem Cell Research, we can see this with global warming, and we can see this with Terry Schiavo. For this reason, many republicans don't care about truth, they don't care about facts, they don't care about science, unless it happens to agree with their ideology.
It therefore makes sense that McClellan would say that the new facts about Schiavo do not change the position of the administration.
Their position was not born from facts, so it cannot be killed by them.