Indeed, the commonplace distinction between the fact of evolution and the mechanism of evolution may apply equally well to design—recognition of a fact of design need not be anchored to an understanding of the mechanisms by which design is introduced into natural phenomena. Incidentally, that point was already made by Paley. (And in fact Dembski’s Design Inference can be read as an attempt to construct an empirical approach to identifying facts of design independent of identifying design mechanisms.)
–Del Ratzsch, “Design Theory and its Critics”
Aristotle argued that a full explanation required four kinds of “causes” (more like “becauses” or explanatory factors): final, formal, efficient, and material. Francis Bacon argued that science should focus on efficient and material causes and leave the rest to the metaphysicians. Intelligent design (ID) theorists are in effect saying that formal causes (designs, plans) should be considered in science, even if final causes are left for others to sort out.
It is unquestionable that we cannot speak much about biology without using some teleological and design language. Naturalistic scientists see this as mere window-dressing that could be eliminated in principle. As for bringing design (back) into science, the scientific community is still Baconian. Some say, Show us the designer and the purpose of the design before we consider it.
Is it possible to discern design without specifying a designer and a purpose or intention? Yes, it is. That is because design, any design, must have one key feature: it must address multiple constraints. Now constraints are not intentions. They just limit the solution space in a certain way.
Consider explanations of law and/or chance. If something happens by law, say a planet moves in a fixed orbit, it doesn’t happen by chance, which would mean unpredictable movement. If something happens by chance, say the shapes of clouds, it isn’t predictable by law except in a general way that leaves open many possibilities. These are opposite explanations and so opposite kinds of phenomena.
But consider then phenomena that is partially law-like and partially chance-like, say the varieties of languages. There are patterns that repeat but there are so many variations we cannot really predict what a newly discovered language will be like. We conclude that language is neither a product of law nor of chance. This means language is designed.
Design is a mean between the extremes of law and chance. If there is only one option, there is no design. If there is effectively no limit on options, there is no design. It is only when there are multiple options and multiple limits on options that design exists. There must be a choice, but not an arbitrary choice, for design to exist.
Are there methods for detecting design? Yes. Entropy is one. When entropy is neither a minimum or a maximum but something in-between, there is evidence of design. Dembski’s explanatory filter is another method. Applied to life forms, there is clear evidence of design in the biological realm. If we follow the evidence and don’t exclude design, we will conclude that design is very much part of biology.
One response of evolutionists is that a mean between the extremes of law and chance may just happen to turn out that way because of evolutionary mechanisms. I would say, first, a mechanism is a kind of design. So-called genetic algorithms show how we can use this method to design things. Second, that does not answer the second-order question: how did this mechanism arise? By law or by chance? An evolutionist would likely answer Chance. But then this is only a first-order design, a single design method that cannot be expected to work in general. A universal design method must be designed itself. Design must be all the way down to explain the myriad of life forms that exist.