What he does is look at the scaremongering of two separate articles.
The birthdayshoes article is well-worth reading; he does a good job of dissecting the unsupported claims in those articles.
After some quotes from those articles, he also provides a nice list of some of the pros and cons of flip-flops.
Among the cons:
You can’t really run in flip-flops very well and you certainly can’t run in them naturally.
To reduce the chance of your flops falling off and to minimize the aforementioned dangling sole (at the heel), people tend to grasp the front of the flip-flop. This isn’t a natural motion — typically your toes point to the sky (dorsiflex) when you walk. This is probably one of the biggest problems with flip-flops because prolonged wear will reprogram your foot to do this grasping thing with every step. Since this would be a bad way to walk barefoot (likely resulting in stubbed toes), well, it’s a consideration in opting to wear flip-flops.
Just a teeny correction: only the big toe dorsiflexes. See the blog entry I wrote on The Human Foot, looking at a book by Thomas Ellis.
Another con, only alluded to, is that because a flip-flop does have a sole, you cannot get the proprioceptive feedback that you get from bare soles.
And there is always the danger that somebody will step on the back of it, making you trip. (There’s actually a lawsuit over that very issue!)
Let me add another, humorous, con:
Among the pros:
They’re super airy! Feet like to breath like the rest of your skin.
They let your toes splay. No toe box means unconstrained toes.
They’re crazy easy to put on and take off. Who doesn’t love this aspect of flip-flops?
When it comes to emergency footwear for getting into some place you really need to get into, flip-flops are certainly the easiest.
His final take? Of course they’re not dangerous, particularly when compared to what full shoes do. I totally agree.
I’d also like to say a few words about the scaremongering in the articles he quotes. It’s just the standard crap about “lack of support”, and unsupported claims. For instance, the first article starts out by saying
According to the National Foot Health Assessment 2012 released in June, 78% of adults 21 and older have experienced one or more foot problems in their lives.
One common culprit of America’s foot pain, especially during the summer, is the flip-flop.
Notice that they give no support for the second statement relative to the first? Is there some increase in pain in the summer for those wearing flip-flops? It doesn’t tell us.
But then they go into the “lack of support” claim. I’ve said this a zillion times before—feet do not need support. Among barefoot populations the “fallen arch” does not exist. Fallen arches are caused by shoes that weaken the arch due to lack of use. As I’ve also said before regarding support, to get people to understand it, suggest that they put their arm into a sling for six weeks. Give it plenty of “support”. At the end of that period, offer to play a game of tennis. Who do you think will win?
And then if they complain about arm pain after the game, is that from the lack of the sling? I don’t think so.
That article also included the crap about “natural surfaces”, and mentions grass, sand, and gravel. But it neglects to mention sun-baked earth trails (such as you will find in Africa and all over the world) that are nearly as hard a concrete. Or large rock surfaces, such as I hiked in Chaco Canyon.
I have to admit that I occasionally use flip-flops. Once, after I overdid a hike (at Yellowstone) but was then scheduled to do another hike, I wore a pair of flip-flops for that ten-miler. I did just fine (though the flip-flops were pretty much done for it).
I absolutely agree with Justin’s conclusion, and add my own spin:
Flip-flops are not as good as bare feet, but way better than regular shoes.