Two or three points here. Sometimes there are no selection criteria because there is no choice. Sometimes such criteria are drastically restricted (as in the example of three-prongs) by the very fact that design (like biological evolution) is a strongly path dependent process. And sometimes even when presented with what seem to be viable alternatives from which one could select one as advantageous over the other, there is no effective way to determine what that advantage is"”what truly distinguishes the alternative"”in which case the selection from amongst them would be said to be arbitrary. We could flip a coin, default lexicographically, or choose first in temporal order, so even when there appears to be no real basis for the selection in terms of "advantage,' we can still make selections in some sense.

I would hazard to speculate that the theory of natural selection, and therefore the concept of fitness, is one of, if not the most, complicated theories ever devised by scientists. There is a reason for that and it hardly needs to be voiced: The fit between the life form (the design) and the pattern to which it must be fitted is exceedingly complex and the process (variation and selection) whereby this fitting is effected is too.
This is just another way that human design is like biological evolution. It never ceases to amaze me that designers are capable of true innovation, when one considers that whatever they invent has to fit into an existing technological infrastructure whose complexity defies both knowledge and imagination.

It's nothing short of a miracle, I'd say! LOL

"If the capacity for and direction of change is front loaded one would still use selection criteria by which to assess the credibility of the theory, right?""”Bradford

In one very interesting way the "capacity for and direction of change is front-loaded." All life on Earth is based on the genetic code. A code defines an intrinsic bias in any changes it admits. Typically codes are defined or described in terms of three basic parameters, and these altogether define the complete design space. I want you to think of these parameters as biases. As defining a capacity for and direction of change. Mike Gene's "theory" vindicated! I've suggested that people think about codes they way do"”as algorithms (because that's what they are). The genetic code, I don't believe, is properly understood in terms of arbitrary representational device, but as a set of effective procedures. Effective wrt what?! Adaptation.

Adaptation = Design?

(Sorry, macht I don't want to ruin your topic by rambling on endlessly and stupidly along any number of remotely tangential topics that interest me, so I'll just shut for a while. Yeh, right, Rock. Like its even possible for you to keep your mouth shut for a minute.)

But since these are designed processes (and not de jure theoretical doctrines like Darwinism or Neo-Darwinism) this is not really an objection to evolutionary computation. Nothing prevents me from designing the evolutionary process to admit "less fit" instances and there are in fact advantages to doing so.

I won't dispute this but would add that selection demands some advantage, however slight, so if the less fit still confers some advantage it would be consistent with neo-Darwinian theory. If the capacity for and direction of change is front loaded one would still use selection criteria by which to assess the credibility of the theory, right?

I saw it: "Human design and evolutionary algorithms share the characteristic of employing multiple iterations, as you point out, but in the case of human design, the "mutations" that are generated are not blind at all, but are the ones that the designer thinks will get him closer to his design goals (i.e. the selection criteria)."

Human design and evolutionary algorithms? Ya lost me right away here. Evolutionary algorithms are human designs. I am sure I don't understand rightly what you were trying to say. And of course, a designer will attempt to skew a search positively in the direction of his objectives. And one of the advantages of evolutionary algorithms (if properly devised), and an advantage that makes them a quite attractive (and sometimes the only effective) alternative to the designer is that they do this automatically. (Which itself suggests that contrary to a common argument that evolution is a ridicuoulsy asteful way to design anything, there are in fact distinct economies involved from the designers'perspective. But no more about that.)

However, kieths, what does the designer do when there is a definite uncertainty wrt to his "design goals (i.e., selection criteria)"? (I think people who have some real-world experience will probably this situation as more typical.) I can tell you what I would do"”I would seek to systematically eliminate in so far as possible any artifactual biases I have unintentionally introduced into the evolutionary design processes, such as in the selection of the code, and in the algorithmic procedures used to generate random numbers, how and when the operators introducing variation into the population of candidates is introduced, etc. Indeed, if I really knew how to bias a search for a solution then more direct methods would naturally suggest themselves to me. So I don't think you've truly identified a difference between design and evolution. But I implied one myself: The evolutionary process proceeds automatically, mechanically, whereas my interventions in the process may not be so automatic or mechanical. (IDers? Any thoughts about that?)

Which reminds me of another design advantage to evolutionary computation: Evolutionary algorithms are "anytime" algorithms, meaning that upon arbitrary termination they can be expected to have found the best solution at that time. Many people have the impression (this is a common argument amongst Neo-Darwinists) that evolution is ridiculously wasteful way to go about designing anything, but there is a definite economy involved from the designers perspective. It saves him the wasted effort of pursuing the incorrect solution to the problem or having no solution in hand or even in sight when an arbitrary deadline is imposed.

This relates to Bradford's question: "Since complex functions are multi-component, each and every incremental addition in its pathway would have to confer a reproductive advantage." But since these are designed processes (and not de jure theoretical doctrines like Darwinism or Neo-Darwinism) this is not really an objection to evolutionary computation. Nothing prevents me from designing the evolutionary process to admit "less fit" instances and there are in fact advantages to doing so. (This is very much like what is done in "tabu" search and optimization methods, e.g.) I think if you will familiarize yourself more with the primary literature you'll find that designers have little interest in conforming their designs to the pet theories of biologists. In the natural sciences things can "work in theiry." In design science nothing "works in theory." It either works or doesn't. In that repect design science is far more demanding than natural science.

Macht asked the question: "In this post I would like to explore some of the implications of evolutionary algorithms (EA's) and what they can (and can't) tell us about design." And it occurred to me if they tell us anything about design we should ask why a designer chooses to use such methods. And to answer that question we should ask another question: What characterizes the problems (and solutions) to which these techniques are effectively applied? Needless to say these are complex problems, definitively problems that are analytically intractable (by "direct methods") for a variety of reasons, such as they are cursed with dimensionality, there are significant unknowns or uncertainties, problems that in short, that do not have any known material implementation that solves.

I realize the bloggers are principally interested in religious matters, but I can't give it a "theological spin." I can't think of a reason why God would bother to perform an experiment. And biological evolution is just an exercise in automated experimental design. And I suppose that's the only reason why biologists think that such designed evolutionary processes can tell us anything about biological evolution.

But that kind of thinking generally befuddles me though. OTOH I do know if there were some really interesting "religious" dimensions to such seeming mundanities it would be missed by persons who a priori make a "hard" (but otherwise inexplicable) distinction between design and evolution. Obviously they are not such different things because biologists generally think life forms evolved, but admit they sure look like they were designed. As if! How would they know?! They are used to asking questions similar to those asked here: What can such evolutionary design techniques tell us, if anything, about biological evolution? Designers don't often ask that question, and likewise biologists never ask what evolutionary design can tell us about design (or designers). But now I'm getting all "designer-centric" and I know that's frowned upon so I'll keep my questions to myself.

And its not topical anyway as macht didn't ask that question. Nonetheless he asked a very interesting question: In this post I would like to explore some of the implications of evolutionary algorithms (EA's) and what they can (and can't) tell us about design.

I think evolutionary design techniques, when consciously embraced and reflected upon (since we all use such techniques but don't always consider that we are doing so) reveals a little appreciated paradigm-shift in the way design decisions can be made (and automated), which I think is interesting, but I don't think its going to be of much interest to the bloggers to explore.

I want to consider a moment another fundamental question, namely, whether there is anything to suggest that every complete functional system confers a survivability advantage (speaking here of the building of function, rather than its degradation). Perhaps each such system performs a function, but is it really a function that provides a survivability advantage?

I would think that evidence for a function conferring no reproductive advantage would also be prima facie evidence for ID. However, the ability to conceive of a selective utility would be an obstacle to the acceptance of the "no advantage" argument. I distinguish between a conceptual utility and a demonstrable one but not everyone does.

I received an e-mail from a friend of mine who is currently employed in the UK as a professor of mathematics. He noted a number of life experiences and some physical features associated with things like appreciating music and beauty and emotional responses; none of which could be unequivocably associated with the conferrence of enhanced reproductive fitness but all of which lend themselves to explanations of resourceful and imaginative minds. This is the kind of speculation observed when empirical support falls short of supporting theorized mechanisms.

Since complex functions are multi-component, each and every incremental addition in its pathway would have to confer a reproductive advantage.

Absolutely right. And that is precisely the point where Behe focused his attention in 1996. In addition to that damning fact, I want to consider a moment another fundamental question, namely, whether there is anything to suggest that every complete functional system confers a survivability advantage (speaking here of the building of function, rather than its degradation). Perhaps each such system performs a function, but is it really a function that provides a survivability advantage?

A contemplative review of nature will suggest examples that appear to have a logical or useful function, but that do not necessarily translate into survivability advantage. The traditional response is inevitably the same: in some long forgotten age the system must have conferred a survivability advantage. Such a declaration is, however, not a statement of fact nor is it an explanation of how the system came about. Rather, it is simply a restatement of the theory. The declaration will often be tenuously propped up with a just-so story, but it will rarely, if ever, be supported by any actual evidence. Thus, we are left with the wonderfully circular "explanation" that the biological system came on the scene because it conferred a survivability advantage. And how do we know that it conferred a survivability advantage? Well, here is it, so it must have conferred a survivability advantage!

Since complex functions are multi-component, each and every incremental addition in its pathway would have to confer a reproductive advantage.

"It was never striving toward porpoises or away from them. Changes simply happened over time; the ones that tended to facilitate survival and reproduction were retained; and we now find ourselves in a world containing bacteria and porpoises, both of whom remain (for now) successful at survival and reproduction."

Assumption based on the theory: changes that tended to facilitate survival were retained and now we have porpoises.

Tautology slipped in the back door (actually right in front of our noses): porpoises were "retained" because of characteristics that helped them survive. How do we know that? Well, because here they are — they survived!

Bonus observation: bacteria reproduce more quickly, with less resources, occupy a greater variety of niches, and get to pass on their precious genes, by all accounts, a lot more efficiently. Again, it is worth asking: Is there any reason to believe, beyond the fact that Darwinism demands it, that every one of the functional complexities we see around us confer a survivability advantage?

For six years I've been begging (literally!) people to tell me what the difference is between "design" and "evolution" and I'm still w/o a clue!

Rock,

See my reply to Eric Anderson above for an explanation of what I think is the major difference.

To me this is the most interesting implication: based on evolutionary biology.

A designer's knowledge of natural processes determines (but not completely) the effectiveness of his control over those process for his own purposes.

Scientists and engineers (by most people's estimation, I presume) are "intelligent designers," and they warrant the designation by controlling natural processes for their own purposes"”including the process of biological evolution.

I would think that the statement of the obvious would have some negative implications for people who habitually refer to evolution as "blind" and "mindless," as if I knew it, or we all accepted it, as a matter of fact.

My experience over the years, Macht, has been that the discussions generally bog down in distinctions between "design" and "evolution."

For six years I've been begging (literally!) people to tell me what the difference is between "design" and "evolution" and I'm still w/o a clue!

In all this time I've certainly learned something about peoples "metaphysical" or "philosophical" stances wrt evolution ("blind," "mindless"), but virtually nothing about design (that I didn't already know LOL).

EA's can produce very complex solutions to problems. For example, look at the antenna designs near the bottom of this page. They were made using a genetic algorithm and they look nothing like an antenna that a human engineer would design. A claim that I've often heard is that the GA designed these antennas, not the humans. But this claim rests on the misunderstanding I wrote about at the beginning of this post. The antennas function in the way the engineers want them to - they fulfill the purpose, the requirements. In this sense, they are designed and they were designed by the engineers

What you say here reminds me of an interview where Sean Booth from the electronic group Autechre discuss the creative methods behind one of their recent albums. Notice his reaction to the interviewer towards the middle… http://www.sas.upenn.edu/~reyn...