The argument goes like this: "Nonsense theories" can have predictive power (like predicting that maggots will form from rotting meat or that the sun will rise in the morning and fall at night, showing the sun revolves around the earth).
This argument is a complete misuse of the concept of predictive power. If you're comparing two hypotheses or theories in order to figure out which is the more probable, and your set of predictions for both is the same, You Are Doing It Wrong. The tool of predictive power is wielded by looking for different
predictions for the rival models, and then performing observations and/or experiments to see which model predicts better.
Let's take the observation that "maggots emerge from rotting meat," and two hypotheses used to explain it: Spontaneous Generation (the maggots just form within the rotting meat) and Biological Origin (maggots are the offspring of adult flies). If we just leave out a piece of meat and observe as it rots until maggots appear, then "the predictions are the same." Ah, but what if we take two
pieces of fresh meat, leave one out as before, but put the second one in a jar with the opening sealed over with cheesecloth held in place with a strap or rubber band? Now we have a setup crafted to isolate one variable--access to the meat by adult flies--and make that differ, while keeping the other variables (temperature, moisture, access to air and sunlight, etc.) the same.
With this new setup, we can now anticipate that if Spontaneous Generation is correct, maggots should still emerge from both pieces of meat, but if Biological Origin is correct, maggots should only emerge from the meat that adult flies can land on to lay their eggs. So now we can compare the hypotheses by running the experiment and observing the results, repeating the experiment as necessary to prevent experimental error.
Predictive power works best when predictions of future
experiments and/or observations can be made, which advocates of both (or all three, whatever) models can agree upon in advance as tests of their models. For example, physicists were able to predict, decades before the Large Hadron Collider was constructed, what sort of energy levels etc. in a particle accelerator experiment would be required to reveal the presence of a Higgs boson, and what the results would look like if it did, or didn't, exist. So, by the time the experiments were run on the LHC, there wasn't a lot of room for goalpost-moving by scientists whose models don't incorporate a Higgs boson.
In the case of evolution and Creationism, we're dealing mostly with the past and with sets of observations (the fossil record, etc.) both sides already have access to. Goalpost-moving is easier under these circumstances, so apart from discoveries made after the rise of the creationist movement (e.g. Tiktaalik, the discovery of Noah's Ark, if that were to happen), we may need to multiply examples in order to make it easier to spot who's moving the goalposts. As with the Spontaneous Generation vs. Biological Origin "debate," we should be looking for the areas where the anticipated consequences of each differ
, not where they are the same.
Since Creationism is really "the Book of Genesis is highly accurate," we can look for observations that do, or do not, match the BoG (while matching, or not matching, the predictions of evolutionary theory). Here is the main area where creationists fail: In order to test a theory, you don't just look for evidence for it; you also look for evidence against it.
Richard Carrier explains this well here
. Creationists are religiously forbidden to honestly look for evidence against Creationism (that might lead them into the snares of the Devil), so they can't perform this crucial step toward making science work.
In order to look for evidence against Creationism, we have to clearly define its truth-claims, and minimize available room for goalpost-moving (likewise for evolution). Since the BoG was written thousands of years ago, we can spell out its claims by applying the Creationist hermeneutic ("Genesis should be interpreted as primarily historical-literal in its intent; it was intended to tell us the actual origins of the Cosmos, life, humans, and the Hebrew nation") and interpreting it as we would if we did not have access to later scientific findings.
In other words, read it as its original audience (or, say, early Christians like Paul's disciple Timothy--call it the "Timothy test") would have read it, if they also employed the Creationist historical-literal hermeneutic. This makes it possible to treat the discoveries of science as "future" findings, rather than trying to read them into the BoG (goalpost-moving).
So, if the BoG is both accurate, and written as a historical-literal treatise, we should anticipate that certain things will be true: rain comes through windows in a solid sky, all animals and land plants diverged from Asia Minor in the recent past, the size, location, and nature of the Sun, Moon, and stars should imply that their function is directly related to the Earth...
God made two great lights—the greater light to govern the day and the lesser light to govern the night. He also made the stars. God set them in the vault of the sky to give light on the earth, to govern the day and the night, and to separate light from darkness.
--Genesis 1:16-18a, bold emphasis added.
...etc.. Creationism predicts that the Cosmos not be significantly older than a few thousand years. Creationists can fudge this a little by applying the concept of "Apparent Age." Since Yahweh created a fully-formed and functional world, at least some things would appear to be a bit older than they really were. For example, Adam and Eve were biological adults or teenagers at the moment(s)
of their creation, the plants and animals were fully-grown, the rivers situated in river-beds, and so on. However, this can only go so far if Yahweh is not deliberately
faking the appearance of an older Cosmos. There's no reason to assume, for example, that Adam and Eve had belly-buttons since they were never attached to umbilical cords. "But maybe Yawheh gave them belly-buttons so they wouldn't have an oddity in relation to their kids/so they'd look like 'standard humans.'" OK, but one thing we would not
expect if we were able somehow to go back and give them full medical exams on the day of their creation, would be for, say, Eve to have scar tissue from what looked like a ten-year-old hamstring injury. Right?
In like manner, we should anticipate that if Creationism is true, that any tree extant at the time of Creation would either have no rings prior to years of life, or if rings are necessary for the trees' survival, to have identical rings, or perhaps rings arranged in some aesthetic pattern. What we should not
see, if Yahweh is honest, is rings of varying thickness which indicate "good and bad tree-growth years" that never happened. Likewise for things like layers in ice cores, craters on the Moon, planets, asteroids, etc., galactic collisions, supernova remnants, and so on. The Cosmos should look
young, and if light has a constant speed (hint: it does!), we should not be seeing light from objects more distant than a few thousand light-years (the distance light travels in a year) away.
Notice in the passage from Genesis above, how the stars are treated almost as an afterthought. From this, we should anticipate that nothing about the stars would suggest they are in any way of equal or greater in importance relative to Earth. There is no way Timothy could read that passage and guess that stars are gigantic, ancient spheres of gas, some of which could engulf our whole inner Solar System if they were put in the place of our Sun. Nothing in the BoG would ever lead Timothy to expect that galaxies
could exist. From the Bible as a whole, we should anticipate that stars are relatively small objects that can fall to Earth
Etc., etc., and so forth.
From this it becomes readily apparent that a "Timothy test" compliant Creationism rapidly gets demolished by bringing the discoveries of science to the table. And that's before we even get
to the fossil record, genetic relationships between species, synteny, ring species, homology, Darwin's finches, and the like. On the other hand, the Cosmos looks exactly
the way evolutionary scientists would expect it to--very, very
old, with a history that is not in any sense "all about Earth," operating according to natural regularities, and so on.
Therefore, in like manner evolution is just circumstantial and not science because it does not actually show a cause of how life evolved. Evolution only shows the outcomes (fossils, DNA, etc) but not the actual causes. Therefore, it can't be science.
I'm not quite clear on what this argument is supposed to mean. Evolutionary theory does
explain the causal mechanisms involved: mutation, genetic variability within populations, and natural selection. Or are they saying something like, "Well, you don't have video of the specific mutation that made Archaeopteryx
diverge from its ancestors taking place, do you? Therefore, HA-HA! Evolution isn't science!" If so, that's just ridiculous. We do science with past events that we can't replicate all the time, e.g. archaeology and crime scene investigation.
So too, it is argued (by creationists) that the inference to greater probability/plausibility is not enough because one must have experience with outcomes (more experience means more statistical data). But we have not experienced "macro" evolution. Therefore, it's not science. It is argued, therefore, that is evolution is "just assumed".
We don't have any current experience with Yahweh writing books either. Much less pillars of cloud and fire, bodies crawling out of graves and the like. That all (supposedly) happened in the past.
Somehow though, Creationists don't seem to have a problem with trying to take their ancient books, use them as data, and attempt to support claims such as "Jesus fulfilled these Old Testament prophecies!" Never mind that their claims can be refuted on the basis of the texts themselves (e.g., the "prophecies" read in context were not written as prophecies in the first place, or were prophecies for some other event, such as a child named "Emmanuel" being born and two of Judah's rival kingdoms ceasing to be a threat before he grew up), they're still deriving conclusions from "evidence" from the past. Any Creationists have video of Jesus' resurrection handy?
Again, this Creationist premise is nonsense. "Were you there?" applies to them and their theory as much as it does to scientists and evolution. Even if it were so that Moses wrote the Book of Genesis (and there's plenty of good reason to think that he didn't), he wasn't there
to see the Cosmos created. At most, we have his claim to have received visionary revelation from a supernatural entity (Yahweh) who was there. But how do we know
that the alleged entity representing itself as Yahweh was really Yahweh, and that Yahweh was there at the creation of the Cosmos? We can't. We would have to take "Moses'" word for it, and that of the alleged entity representing itself as Yahweh. It's hearsay
Also, Creationists have yet to demonstrate that there is there is an actual distinction between "micro" evolution and "macro" evolution that is any more relevant than the difference between a "micro" road trip ("Let's go to the store!") and a "macro" road trip ("Route 66, here we come!") to claims about the possibilities and limits of automotive travel.
And one more thing: Creationists are actually more
"evolutionist" than evolutionary scientists. One of their main "scientific" claims is that the present enormous variety of species diverged evolutionarily from a relative handful of "kinds," a number of types small enough to fit on Noah's boat. Thus, the "cat kind"--house cats to tigers, the "elephant kind"--elephants, mastodons, mammoths, etc., all emerged in a rapid process of super-evolution
from the two/seven of each "kind" on Noah's ark within a few thousand years, rather than the many millions of years scientific evolution would require for an equivalent amount of change.Edit: