Det skrev jeg forleden en kommentar om ovre på Pleiotropy, som egentlig fortjener at ophøjes til et helt indlæg her. Kommentaren tager udgangspunkt i en bemærkning om, at irreducibel kompleksitet – argumentet om, at en levende organisme er så kompleks, at fjernelsen af blot en enkelt komponent vil få den til at fejle, og derfor kan den ikke være opstået ved en tilfældighed – egentlig er et sundt, videnskabeligt argument, der er bare ingen observationer, der peger i retning af, at det er relevant for livets opståen her på Jorden:
First of all, I think that the argument of irreducible complexity is a bad argument because it’s a reductio ad absurdum.
Such arguments work extremely well in mathematics, but in empirical science their track record is bad because some way around the “absurdity” might be found which the proposer of the theory hadn’t thought of.
E.g., the existence of the ether was once considered necessary, even proven, because waves (light) can’t propagate in nothing, i.e. vacuum.
Except they apparently could: No positive evidence could be found for the existence of the ether, and in 1905 Einstein famously showed that the ether is not necessary for the consistency of the theory of electromagnetism.
Likewise, saying that irreducibly complex systems can’t arise spontaneously is equal to saying just about nothing, since in some cases they actually can – in physics I believe we see it in chaotic systems and resonance phenomena.
So if the ID people and creationists really wanted to go places they’d want to find positive evidence that point to a creator or designer – evidence that could supposedly tell us something about said designer’s nature, tools, methods, etc. Alas, such a theory is probably not forthcoming.
Carl Sagan had an outrageous idea in one of his novels, that the Creator had signed his work by embedding a representation of a picture of a circle in the decimals of Pi – the ID people would have to come up with something similar if we are to take them seriously.
Even so, I tend to agree that the argument of irreducible complexity is scientific, even if it is potentially flawed. However, I think that what makes the ID theories really not science is that they’re not falsifiable – there’s no experiment we could design or perform which would make these people change their mind. And if you’ve already made up your mind (or let your religious ideas make up your mind) as to what class of phenomena you will accept from Nature and what kind of theories you will use to describe them, then you’re not a scientist period.
Pleiotropy er i øvrigt et godt sted at gå hen, hvis man gerne vil læse kvalificerede indlæg om evolutionsbiologi, striden om Intelligent Design og en masse andre beslægtede emner.