The short answer is that I don't. A longer answer is given here. Ultimately, I get asked about Mr. Thein but not about Mr. Newhall because Beaumont Newhall doesn't have many fans on the internet with a personal investment in his ideas. Also, Mr. Newhall, being dead, isn't continuing to say dumb wrong-headed stuff, and finally Newhall doesn't use a carefully constructed personal narrative as an important part of his authority.
So my remarks on the gentlemen are different in shape and flavor, as are my remarks on the subject of several other fellows I think have infested our world with bad ideas.
But ultimately, it comes down to this:
People say stuff. Some of it is right, some is wrong, some is clever and some is dumb. There are people with outsized influence. Beaumont Newhall managed, somehow, to become the authority on the history of photography, and he managed to become, to some degree, the sole authority on who matters and who does not in that history. And he's wrong on several counts. Ming Thein has become positioned as an authority on several technical matters, and he's wrong about some of them. Michael Reichmann, Keven Raber, Lloyd Chambers, the list goes on.
It's not that any of these chaps are evil. They're human. Some of their ideas are better than others. Some of their ideas are really just prejudices dressed up as facts. Same as it ever was. I'm the same way.
But the influencers, these people with outsized weight in the eyes of the world, need to be questioned. When an influencer says something dumb, it is important that someone point it out. More precisely, when we think that something an influencer said is dumb (accepting that we might be the wrong one) we should point it out. Let the cage-match of ideas begin, and the best ideas win. The point is not that I am right and Reichmann is wrong. The point is that we should be examining these things critically. It is virtually the definition of an influencer that their ideas don't get examined critically, and this we need to fight against, always, in all walks of life.
You would think that the influential writers of today, working in media where this critical examination could take place in situ might allow it, but as a general rule, they do not. These people are, generally, not very interested in being examined. They're selling themselves, they're selling products, they're managing their brands. And so, they choose to interpret disagreement as personal attack, and then shut it down on that basis. I can think of at least two different examples off the top of my head where I have personal experience of this. I assume it's nearly universal. The cage match of ideas must happen, therefore, elsewhere.
Photography, especially the pedagogy of photography, is simply awash in stupid shit influential people and publications have trotted out. If only a few more people had stood up in the 1970s and said "this rule of thirds thing is stupid and wrong" then we wouldn't have to deal with it today, and the pictures on flickr would be measurably better than they are. A billion pictures have been damaged by a piece of shit that "Popular Mechanics" trotted out in 1970.
Down with the Man. Fight the Power.
But it is kind of fun to pick on Ming, gotta admit it.