Perhaps I can mediate a bit here.
I am scientifically oriented, as those of you who have read my posts here know, but I understand why Eric O and Chad take the position they do. It goes back to a favorite medical anecdote I have mentioned before on here: one that takes a little knowledge of chemistry to appreciate.
West German scientists in 1957 introduced a drug, Thalidomide, to combat morning sickness during pregnancy. However, they synthesized a right-handed chiral isomer of the drug. A chiral isomer (as of an amino acid) simply indicates the way the molecule orients its structure. As RJKD already noted in another post, the classic example is your hands: your left and right hands, when put together to pray, are identical: mirror images. But they are not truly identical, because on one the thumb is on the right side, on the other, the left side. The same structural diversity is possible in amino acids. Interesting, though, given this possibility, is that only the left-handed forms are found in nature. Now, when the scientists introduced thalidomide, I believe other drugs using right-handed isomers had already been introduced to the medical community, and achieved their desired effect. The incentive to produce this less natural form was because it was cheaper and simpler to manufacture. But with thalidomide, this happened:
When Thalidomide was taken during pregnancy (particularly during a specific window of time in the first trimester), it caused startling birth malformations, and death to babies. Any part of the foetus that was in development at the time of ingestion could be affected.
For those babies who survived, birth defects included: deafness, blindness, disfigurement, cleft palate, many other internal disabilities, and of course the disabilities most associated with Thalidomide: phocomelia.
This is the reason the FDA is so stringent in the USA today, and Europe is (by comparison) making guinea pigs out of their citizens. The advantage is a lot of cutting edge phamaceuticals are available in Europe years- sometimes even a decade- before they are available here. The disadvantage is illustrated above.
So I understand why people are sometimes distrustful of science; it is the ambition of science to remove subjectivity (and scientists seem to me far more committed to that ideal than the journalists I've known who never stop quacking about it), but this is impossible, or nearly impossible, and science is usually flawed. When it is not flawed, it is incomplete. What science achieves today is a stepping stone to what it will reveal tomorrow; it is the method- the analytical method- that is constant, and in which I believe.
But science isn't perfect, and that's why I understand, when our knowledge of a subject is vague (which, as I have reviewed it, seems to be the case with artificial sweeteners), I understand the desire to be conservative, and try to maintain the "natural." Because...the natural didn't give us a right-handed thalidomide. It also didn't give us a left-handed thalidomide, which is safe and effective, and it did give us morning sickness...but it didn't give us right-handed thalidomide. I understand the nature of distrust, there.