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Upon further reflection, I should correct myself for making a connection in my original post that really should not have been made: I made the case that "intelligent design" and "irreducible complexity" were one and the same, when in fact they are not directly related. "Intelligent design" (ID) is different in that it is based more on philosophical and rational argument than on scientific evaluation, which is probably why it is easier to make a logical case for it.

I will use a parallel to make an argument in favor of ID over evolution, based on what is known in philosophy as the Allegory of Paley's Watch.

Suppose you live in a small village on an island somewhere in the South Pacific. You live in conditions that would be described as "primitive" by our standards, and you have no exposure to the outside world. While walking along the beach one day, you come across a large pile of driftwood and other assorted things that have been washed up by the tides, seemingly at random. In the midst of the various things on the beach you come across a gold watch, though your primitive circumstances and lack of exposure to the outside world make you thoroughly ignorant of what exactly this thing is.

The point that is made in Paley's allegory is that a rational person in such a situation would be able to deduce that the item was different than all the other things washed up on the shore. It would be clear to you that this watch was not the result of a natural or random process but of a creative process, and even though you do not know the purpose that this thing serves (and even if the watch is not working when it lands on the beach) you would base this presumption on nothing more than the complexity of the object in your hand.

You can take this allegory one step further. Imagine that while walking along the beach you come upon a pile of driftwood in all shapes and sizes, all of the pieces worn down in a random fashion by the wind and the waves. Now suppose that in the midst of this pile you find one piece of wood that is not worn like the rest but is carved in some intricate manner into a figurine or even some other form that you don't recognize. Once again, any rational person would recognize that this carved piece of wood had an origin that was "higher" than the random pounding of the waves, and once again you would make this case based on nothing more than the complexity of the object in your hand.

It is important to note that no process of scientific evaluation would ever be able to validate your theory in either case (assuming, of course, that you were never able to leave the island and look for the source of these items). What is also worth noting is that it is not entirely impossible for these objects to have washed up on the beach as a result of a random process. It is theoretically possible for the wind and the waves to erode a piece of driftwood in such a way that it assumes a complex, intricate form. It is far less likely, but also theoretically possible, that the various minerals and elements required to form the watch (gold, nickel, glass, etc.) could be brought together in a random process to produce the objest in your hand.

And yet despite the lack of "scientific proof" to support the theory of an outside creative cause, and the theoretical possibility that these objects were the result of a natural process, the person who believes that these things were created at random is the one who is actually making an irrational leap of faith!

OK, lets work with that analogy. It will help you get straight on some basic concepts, like the relation between observation and theory. Question: What must be true in order for an observation to count as evidence in favor of a theory? Answer: The conditional probability of the observation given the theory must be greater than the conditional probability of the observation given the denial of the theory. (Bayesians: I'm on your side, but Paley's argument seems to presuppose Edwards Likelihood Principle so let's play along for the sake of agrument.) Apply that to the watch example: The conditional probability of finding a watch given that there was a designer is greater than the conditional probability of finding a watch given that there was no designer. So far so good? OK, now apply that principle to the present case. Paley didn't have the wealth of observation to work with that we have now. So he might be making a reasonable inference from the information available to him and _still_ be as wrong as people in the 3rd century BC who inferred the world was flat because gosh darn it looked flat. Observation: There are structural similarities between creatures that have no functional explanation. Ie two legged and four legged mammals have the same skeletal structure. Apply the likelihood principle. Is the conditional probability of this observation greater assuming the truth of intelligent design or is it greater assuming that two legged and four legged animals have a common ancestor?

There is a problem with your allegory -- when a scientist looks at a living organism, such as man, if he sees that organism as designed he would wonder at the sanity or sobriety of the designer. Let's take man, for instance. The human back is a rather poor compromise between the horizontal back of a quadruped and a proper upright spine. Because of this humans suffer an inordinate amount of back problems (you may have noticed this on your own). Additionally human knees are not quite up to an upright stance, either, causing all sorts of knee problems especially as we get older. The human eye, as has been pointed out before, has a major blind spot right in the middle of its field of vision. This is because the optic nerve lies atop the retina. Humans (and our closest cousins) cannot make Vitamin C which is vital to survival.

Now, evolutionary science can explain all these things (the knees and back because up until relatively recently [geologically speaking] we went around on all fours, the eye because it is the ad hoc affair it appears to be and the Vitamin C deficiency because in our "natural" habitat Vitamin C was plentiful in nature so our bodies didn't need to make it any more.