I'm sure you all recall the recent $20,000 SENS Challenge results and the ensuing high-quality commentary from the healthy life extension community and wider blogosphere. SENS, the Strategies for Engineered Negligible Senescence, is an engineering approach to preventing and repairing the root causes of degenerative aging. The approach - and the underlying points that aging is the biggest problem we face, and that we know enough now to make good progress within our lifetimes - is garnering increasing support and interest.
By way of a reminder, you can find the various challenges, responses and counter responses at the Technology Review website.
Since the results were announced, Michael Rae - calorie restriction advocate, MPrize supporter and Aubrey de Grey's research assistant - has taken the time to prepare a fairly lengthy and detailed reply to the counter response provided by Estep et al. It's densely written and point by point, but if you've been following the debate you should certainly read the whole thing. Casual readers may want to scroll down to find the link to Chris Hibbert's analysis, which is written in more of an essay style.
I will briefly say that Mobbs's reply seems to be redundant to his original, which was already pretty weak, and intentionally ignores the specifics of Aubrey's reply; Weinstein's is too vague to be taken seriously, not presenting any evidence or seriously engaging the arguments, EXCEPT for his more detailed presentation of his histological disordering argument, which should've been made in his original rather than presented in argument to Aubrey's rejection thereof; and that Estep et al's reply was, as the judges rightly said, the most cogent. It's unfortunate that there is no mechanism for a direct counter-counter-rebuttal; here, I offer a somewhat informal attempt at the same.
Estep et al then make an attack on the Wright Bros. analogy. This would require an essay in itself to disentangle. The key points are that (a) de Grey is not claiming that we could do engineering with NO basic research, but that in the specific field of biogerontology, basic research has progressed to the point that no FURTHER basic research is required to devise a second-order, engineering solution to aging (with the "life-expectancy escape velocity" caveat mentioned above); and that (b) de Grey is entirely in favor of "every critical component of [SENS] be[ing] rationally designed and repeatedly tested" on exactly the same basis that the Wright Bros. tested their plane: *build* the thing, first plank-by-plank/component-by-component (as an intervention against a specific kind of damage and an ensuing disease state) and then as a complete platform (to reverse aging), testing them individually and then in unity. Given more time, one-to-one analogies could be drawn between various plane components and various specific SENS interventions.
For further reading, I recommend this equally lengthy analysis from Chris Hibbert:
In their response, Estep et. al. point out that the Wright brothers used the scientific process to test and evaluate the components they were building, and that they were systematic in their efforts to evaluate all the effects that mattered in getting into and remaining in the air. This response completely misses the point. Estep et. al. think that progress is made by systematically expanding the frontier of what is known. de Grey proposes to take what is known and build an effective mechanism to solve a problem, learning as he goes. The relevant question is whether we know enough at this point to start the process. The Wright brothers didn't know the answers when they started. They weren't satisfied with asking all the interesting questions, either; they asked the questions that were blocking their path to building a successful flying machine. Useful questions for critiquing an engineering proposal include: Do we know enough to get started? Is the cost estimate reasonable? Are there reasons to believe that there is no solution to the problem (within the budget)?
Overall, I have to agree with TR's panel. Estep et. al. may have found some holes in de Grey's specific proposed therapies (it's hard for me to tell; unlike de Grey, Estep et. al. don't provide layman's versions of any of their technical arguments), but they didn't show that these holes make the entire effort unlikely to succeed, and they didn't show that de Grey's proposal doesn't address a useful goal.
Again, you'll find a great deal more there to think about; go and read the whole thing.