If Darwinian theory is tautological, why was it so controversial? Indeed Darwin knew it would be, and so kept it secret for decades after conceiving it. Why does it continue to be controversial to this day in some places, such as the U.S., to the degree that organizations like the one you cited (the Discovery Institute) are dedicated to dismantling it?
The core of Darwinian theory is not "what survives is fit; what is fits survives." The core of it is:
1) Life can multiply extremely rapidly, outstripping the available resources to live on, meaning that only some offspring can survive (this comes from Malthus)
2) There is random variation in the characteristics of offspring, some of which will prove more successful at survival and reproduction than others.
3) The action of (1) and (2), starting from some unknown point of origin of life, can explain all the variation in types of life that we see around us today, from fungi to humans.
I think you misunderstood the person you’re responding to. They are saying that the way we take in calories is so far removed from the environment we evolved in that any Darwin comparison is smoke and mirrors. IMHO they are spot on.
Gilder co-founded Discovery so you'd have to assume this essay is somewhat representative of the kind of thinking that inspired its creation. I've read plenty of Gilder and I honestly don't know what his exact views on the origin of life are. I'm sure he has his problems, but doubt they have much to do with whatever the original opposition to Darwin was. The point is very much that it doesn't matter. A purely deterministic and materialistic theory of evolution could be perfectly true, yet one has to concede it cannot possibly give us much of an edge in solving today's problems. The meat article made me think of Gilder's essay because it's a perfect example of trying to employ Darwinian thinking when it cannot possibly help.
The core of Darwinian theory is not "what survives is fit; what is fits survives." The core of it is: 1) Life can multiply extremely rapidly, outstripping the available resources to live on, meaning that only some offspring can survive (this comes from Malthus) 2) There is random variation in the characteristics of offspring, some of which will prove more successful at survival and reproduction than others. 3) The action of (1) and (2), starting from some unknown point of origin of life, can explain all the variation in types of life that we see around us today, from fungi to humans.
None of these are tautologies.