My attempt at a holistic answer to the OP. “Evolution” as a whole isn’t so much a single theory as the the inevitable outcome of some underlying ones. So I think you’d have to falsify one of them.
Evolution in this scientific sense is basically six postulates: three genetic ones, and three environmental ones.
The genetic ones:
Offspring inherit traits from their parents. (Inheritance)
At least occasionally, offspring will manifest a trait not inherited in any parent (Mutation).
A certain amount of similarity is required for one organism to produce offspring with another (Speciation). Stated in the negative, sufficiently different organism will not, and–if the difference is large–cannot, have children together.
The Environmental ones:
Certain traits increase or decrease life expectancy in specific environments.
Statistically over large numbers of organisms, organisms which live longer have more offspring.
Environments change over time and/or space.
Everything else follows from these six. So to falsify evolution, you need to either:
- Demonstrate that one of these six is false, or
- Demonstrate that another condition is necessary, AND demonstrate that it’s false.
The usual one to attack is (3), which requires demonstrating that a large number of observed speciation events are faulty or not reproducible
More accurately, “anti-evolution” proponents generally attack combinations of them: “Sure, changes happen, but they don’t add up” or “Things can change, but never so much that speciation happens” or “Environments don’t change enough to cause speciation” or the positively bizarre: “Sure, some creatures are evolving, but most don’t.”
To answer a couple other points raised here at random:
Colibri, it has been my experience that proponents of Intelligent Design generally do deny that organisms have evolved, but it’s a quibble. More importantly, I think, is that their postulate is stronger than you stated. Specifically, that the evolution of complexity (usually stated as intelligence) REQUIRES design by a designer of greater (or at least equal) complexity. This axiom is trivially shown false by failure of induction. There’s no base case, God (or whoever) would have had to have been designed by a still greater intelligence,and so on. The introduction of the idea that “God is an exception” is religion, nonfalsifiable, and another point at which ID ceases to be science: it’s the redundant “introduced” non-created being necessary in the first place only because we don’t accept the universe itself being non-created.
kanicbird The sexual reproduction one is pretty easy, actually: once the work of “constructing” the fetus has been differentiated to different cells (which occurs even in asexually reproducing creatures), there’s no barrier at all to the different parts being in different creatures. The whole penis/vagina thing would take a while to develop, but simple proximity sharing of genetic information (by rubbing, pollination, separated laying/fertilizaton events (like fish), actual intermingling of two organism, etc.) is easy, and everything after that is just a jump.
In fact, assume you’ve got an organism with both “male” and “female” genetic material (which exist), and a relatively easy way to share it with those organisms around it, such as these http://www.hi.com.au/resource/rfacts.asp?kla=1&subtopicid=1143
Once you’ve got that, losing the ability to asexually reproduce might not be be a disadvantage if breeding partners are readily available, so a mutation that caused an either/or creature to be sexually reproductive only wouldn’t necessarily select against them.
There’s some interesting papers on this on the web, but I can’t find one that’s just HTML and not PDF or Powerpoint, so just google on “both sexual and asexual”. Oddly enough, this seems to be a mostly work-safe search :dubious: