I often see misunderstanding of what ID is about. It’s about inferring design by critical analysis of a pattern and the ways that pattern could have come to exist. I find a comparison with a lottery to be the easiest way to understand this.
Suppose there is a state lottery and each month for 12 consecutive months 10 million tickets are sold and one winning ticket is drawn at random. Obviously there must be 12 winners at the end of the year. While each winner beats odds of 10 million to 1 there’s nothing unusual about that as someone must beat the odds each time.
Now suppose that the 12 winners are all siblings in order from oldest to youngest.
This lottery result constitutes a pattern.
First of all we have complexity in the pattern. The odds of any particular sequence of 12 winners are 1 in 10^84 (that’s 10 followed by 84 zeroes). Any single pattern where there are trillions and trillions of patterns possible is complex. But complex things like this happen all the time because the result must be one of those many sequences. A sequence of 10 coin flips, no matter the result, is not complex as there are only 1024 possible results. This is roughly how we define complexity. Complex results happen all the time and in themselves are no indication of design.
Next, the pattern has specification. The pattern conforms to an independently given specification. In this case siblings from the same family is the indendently given specification.
Now we have identified the lottery result as a complex specified pattern (or complex specified information if you will). This is a reliable indicator of design. The more complex the result and the more definitive the pattern the more reliable the design inference.
No matter how convincingly it can be told that the lottery was secure from cheating no reasonable person will be convinced that there was no cheating involved. So we can almost certainly rest assured that the result of the lottery was not random but was the result of design (cheating; rigged).
However, even though we know the result was rigged we have no clue how it was rigged (the mechanism) nor who did the rigging (the designer).
ID is the theory that certain patterns in nature exhibit specified complexity that can only reasonably be attributed to design. ID does not and cannot reveal how the design was accomplished nor what entity or entities did the designing. ID is nothing more or less than design inference based upon high improbability of independently given patterns arising by chance.
Now let’s quickly look at the flagellum. There’s no room for debate about complexity. It’s a precise arrangement of millions of protein molecules from a set of dozens of different proteins, each protein itself a complex pattern. There’s little room for debate that it conforms to an independently given pattern. It’s a propulsion device. Where there is room for debate is in what Bill Dembski calls “probabilistic resources”. These are the resources that “chance” (or unintelligent cause) has to draw upon in forming the pattern. This is why ID seems to be an attack on mutation & selection. Mutation & selection are the leading known probabilistic resource that could form the specified complexity of the flagellum.
Logically one can never prove a negative. ID proponents will never be able to prove that some unknown probabilistic resource wasn’t the source of design in the flagellum. However, this is a problem with nearly every hypothesis in science and it’s why you often hear that all of science is tentative. Some bits are just more tentative than others. This is why most philosophers of science say a hypothesis has to be, at least in principle, falsifiable. If we can’t prove something is true, if we can at least be able to prove it false in principle, then it’s science. The ID hypothesis of the flagellum is falsifiable. In principle a neoDarwinian pathway for its evolution can be plotted on paper and confirmed in a laboratory.
The greater question in my mind regarding falsifiability is whether there’s any method in principle of falsifying a hypothetical neoDarwinian pathway for the flagellum. The only real contender for falsification is a design inference! So you see, if ID didn’t exist, neoDarwinists would have to invent it just so they have a method of falsification in principle for random mutation plus natural selection in creating things like the flagellum.