Compare:

http://www.alanaragonblog.com/about/

to:

http://chc.ucsf.edu/coast/faculty_lustig.htm

I'm not saying that's dispositive, but why exactly is Alan Aragon more credible than a medical doctor and UCSF clinical pediatrics professor?

I've never heard of Alan Aragon, but he claims to have a master's degree in nutrition. That's a HELL of a lot more nutrition training than your average MD gets.

I'm sure both have tons of post-degree self-study in nutrition, and that's virtually impossible to measure.

The problem of quantifying levels of expertise is a hard one, especially in the world of nutrition.

In the UK things are slightly easier. The word "dietician" is reserved. It is illegal to call yourself a dietician unless you have specific qualifications and are registered.

Anyone can call themselves a nutritionist. I could set up shop tomorrow, calling myself a nutritionist.

That's made a bit more complex because you have sensible nutritionists working within public health doing real science, and you have wingnuts.

The word 'dietitian' is protected similarly in the United States, and the word 'nutritionist' is similarly unprotected.

In this case, Lustig is a professor at a major medical school and is the director of a university clinic that focuses on obesity. He has also done substantial published research in the area. In comparison Aragon's only formal credential is a master's from an unspecified university. So if we're going purely on credentials, I think Lustig wins.

I would go with: Bio PHD > MD > Masters in Nutrition

I'll admit that I'm biased, because my wife has a PhD in nutrition (as well as being a registered dietitian), but my best friend from high school is now an MD, and my wife knows more about nutrition and its effect on the body than he does.

Also, I'm aware that's merely an anecdote. Based on purely empirical evidence, I'd place both my wife and my friend in the top 10% of their respective fields, though.

Though of course, if the sugar question was a settled question in nutrition science, this thread wouldn't be happening, so comparing credentials isn't really relevant to the sugar question.

I disagree.

The sugar question is settled in nutrition science. Sugar that doesn't occur naturally in food is pretty bad for you. But underqualified people have different opinions and get a disproportionate amount of face time on media.

In fact, I'd say the question is almost identical to the climate change 'debate'. The science is settled, but the average American doesn't know who to believe.

How can something be merely anecdotal and empirically evidenced at the same time?

You've misread his comment.

The comparison of his wife and best friend is the anecdote.

He then adds separately that he has empirical evidence--unshared with us--that each is competent in their respective fields.

He doesn't claim anything to be simultaneously an anecdote and empirical evidence.

A good reason why lustig spends much of his talk discussing the chemistry of sugar metabolism.

Definitely can't argue with you there. Although AA's arguably the leader in his field, a top sports nutritionist going against any sort of deeply credentialed scientist/doctor is going to be put at a credibility disadvantage.

I encourage you to read the two articles though and see what you think.

Are you arguing proof by appeal to authority?

No, obviously, I'm rebutting an appeal to authority.

The parent posted a link to a 1,500 word argumentative essay backed up with inline references to 19 peer reviewed journal papers and included the words "check it out here and make up your own minds". Instead of making any comment on the content of said essay, you merely compared credentials of the speakers.

Which poster seems more guilty of a fallacious argument?

Did you actually read the linked articles and the referenced links? They don't say what the AA claims they say. He makes scientific statements that can generally be inferred from the cited sources, but which the sources don't actually prove.

It would be like some guy saying that physical money is bad and referring you to a CBO publication about hyperinflationary currencies.

I read both links but only 4 abstracts of the referenced articles (which on their face seemed legit but I did not have access to the full articles. His analysis of the last 37 years of American diets seemed accurate based on http://www.ers.usda.gov/Data/FoodConsumption/ compared to what Dr. Lustig cites for 6 years for children.)

If you disagree with one of his conclusions, please post your thoughts - but be specific. I'm open minded... if "He makes scientific statements that can generally be inferred from the cited sources, but which the sources don't actually prove"...I'm happy to agree with you but that seems like that would be simple to show but you don't link to anything or provide any arguments or even a sentence or two to back it up.(?)

I don't have a horse in this race, but I'm not going to discount someone just because they aren't a professor at UC-SF.

The problem with this comment is that it assumes I have a horse in this race too. I think maybe you'd have been better off posting a comment on the root of the thread rather than attaching it to mine.

This right here is one of the more annoying message board tics.

I'm pretty sure that's not what people mean when they talk about appeal to authority. An actual appeal to authority is fine. A fallacious appeal to authority is one where the 'authority' in question has little or questionable authority in the area being discussed.

Here is a possibly legitimate appeal to authority, although you could refute it on its own grounds :-) http://en.m.wikipedia.org/wiki/Argument_from_authority

An actual appeal to authority isn't "fine", it's saying

"Accept my logic as correct because I namedrop a well regarded name as a supporter". But since well regarded people can be wrong this is no sort of proof at all.

I think you need to read the Wikipedia entry on Argument from Authority.

Aragon's "rebuttal" of Lustig is nonsensical.

He completely biffs Lustig's position on fruit (vis a vis Atkins Diet). In that lecture, Lustig says fruit is okay, whereas fruit juice isn't, because the fiber in fruit blocks the fructose from being metabolized, while the glucose gets used.

Lustig may be right or wrong. But criticisms should be about what he actually said.

Since Lustig publishes his research and results, Aragon could step up act like a scientist and either refute or confirm Lustig's data. But sciencificalologeries is hard work, whereas just making shit up is pretty easy.

Further, while I'm on board with Lustig's science, and conclusions, and strategy, I've personally adopted a nutrition somewhere between Eat To Live and Dr Terry Wahls "eat 9 cups of fruit and veggies per day". Works great for me.

Yes, this. I just watched the Lustig YouTube lecture and then read Aragon's rebuttal. Aragon is arguing either with things Lustig didn't say or with small bits taken out of context.

In particular, Aragon doesn't seem to get the difference between a lecture and an academic paper. One can't edit a lecture, so you have to give the speaker a little leeway. Aragon also can't seem to tell the difference between a rhetorical flourish and a claim of absolute fact. Disappointing!

Dr. Lustig's rebuttals:

http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-ab...

http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-ab...

http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-ab...