The other day someone in a certain forum I belong to posted some predictions of creationism. I responded to him. Quotes from him are in italics, my words are in bold:
1. Common designs among diverse species – if a designer is in view, one would expect similar designs to appear in species that are not related. If evolution is true, nearly identical designs would necessarily be related. (examples which prove this prediction are the eyes of the chameleon and sandlance (fish), and the bill of the duck and platypus. (regarding this is a wonderful quote from Stephen Jay Gould who unwittingly insists that design convergence is impossible)
Evolution predicts that the chameleon and the sandlance inherited that similarity from a common ancestor. The fact they both have similar eyes is of no consequence to either creationists or evolutionists because it fits just fine in both views. However, creationists can't really use the "common design" argument. Why would God create the wing of the bird, the flipper of the whale, the paw of a dog, and the hand of a man with the same underlying structure? Why not give the whale a propeller? It makes more sense if the common ancestor of all these creatures had a five-fingered hand that was modified for different uses as time went on. Besides, even if there were some reason god would want to make things the same, why didn't he design the wings of the bat, bird, and pterosaur the same? See here.
An evolutionist would solve that problem by arguing that there are lots of ways to make a wing from a five digit hand, and since each lineage (bats, birds, and pterosaurs) evolved separately, each one evolved its wing a slightly different way. How do you explain it, without being inconsistent with your idea of "common design"?
2. Fine tuning – honestly, if the weak refutations of the “fine tuning” argument have caused you to dismiss this argument, fine. But one should consider that this aspect of the universe is predicted by a design model and in opposition to a naturalistic model. So predicting future scientific discoveries based on the premise of a creator must mean that more fine-tuning characteristics will be discovered, the degree of fine tuning discovered will increase, evidence of fine tuning regarding humans will be far more pronounced than for life in general, and most significantly, ALL life on earth both past and present will be found to serve some purpose directly related to the needs or pleasures of humanity.
The fine-tuning of the universe was never predicted by theism. Don't get me wrong, its still possible that theism is the best explanation for the fine-tuning, but it is not a prediction of theism.
The reason I reject the fine-tuning argument for God is because:
1. It just raises the question of where such a complex and fine-tuned creator came from (and if his complexity existed forever, or with no explanation, we may as well say the same about the universe). It is possible that the universe existed forever, as there are lots of cyclic cosmologies that are plausible (See here).
2. Testable multiverse theories (such as Smolin's cosmological natural selection hypothesis) have been put forward.
3. Multiverse theories are not less preferable than God. Some critics object that the multiverse violates occam's razor, but if it does, so does God: The god hypothesis requires positing a brand new kind of entity, while the multiverse only demands that we posit more of the same type of entity that we know exists (the universe).
3. Astronomers will continue to find new evidence which shows that the Milky Way Galaxy is unique in its capacity for a solar system like ours, our solar system is unique in its capacity to have a planet like earth, and the earth is unique in its capacity to support life (no matter how may trillions of galaxies are discovered).
I've got more where these came from, but I'd really like to hear an argument to the "fine-tuning" of the universe that doesn't involve an untestable theory without a shred of evidence (I am of course referring to the infinite shrinking and expanding of the universe).
I don't see how prediction 3 follows from theism. In any case, the evidence so far shows otherwise. I've written a great deal on all these matters, you can check out my writings in book, "Atheism and Naturalism".