From a materialistic point of view (the point of view of evolution) there is no essential difference between living things and non living things. In fact, materialists claim that living things arose from non-living things so (to materialists) they are essentially the same. Since they are (again according to materialists) have the same properties it is not unfair to ask that if one can see design in non-living things that the same criteria can be used in the case of living things. The argument of intelligent design thus boils down to that if one can easily discern that a complex, interrelated, purposeful object was designed in the non living sphere of things, that such criteria can be equally well used to determine design in living things.
Since evolutionists claim that randomness is the source of change, it is legitimate to ask what chances there are for so many random changes to have occurred? The criteria which Dembski uses is that if there is only one chance in 10^100 that something happened, then it is fair to say that it was intelligently designed. Unlike what evolutionists claim, such chances can be scientifically determined with our present knowledge. The chance of arriving at say a correct DNA string for a certain gene can be easily estimated by using the 4 possible codes to the power of the length of the DNA bases of the gene (ie a gene of 900 DNA bases which is average to small has a chance of occurring at random at one chance in 4^900). This can be tested in the lab by making substitutions and seeing what changes would allow it to properly function. Such tests have been made and continue to be made and the possible substitutions are few and far between. It would be extremely generous to allow the example gene to have one chance in 2^900 of arising at random - which is a virtual impossibility. When one considers all the numerous absolutely new genes that would have had to arise totally at random to create just the 1.5 million known species, one has to see that evolution is totally impossible because as I say, a chance of a near impossible event can be attributed to luck, a chance of numerous nearly impossible events occurring is totally impossible and a ridiculous assertion.
How many times you gonna sing this song? If you and Dembski don't know EXACTLY how something occured, you don't know how to quantitatively express the state-space, and the selection criteria, which means you don't know diddle-e-squat about what the computed probability was.