Not really either, it’s a neat way of saying that a hypothesis doesn’t actually explain anything: it doesn’t provide a deeper explanation for the phenomenon in question (this explanation is the “moving parts”).
A hypothesis allows you to make predictions; a good one will clearly express how and why various factors are combined to make the prediction, while a bad one will at best give the “how” without providing any deeper understanding. So a bad hypothesis is a little like a black box where the internal mechanism is hidden (sometimes, “no moving parts” might be better expressed as “unknown moving parts”).
This idea occurs in the sequences, but the best explanation of the meaning I can find there is (source):
[...] the hypothesis has no moving parts—the secret sauce is not a specific complex mechanism, but a blankly solid substance or force.
(The “secret sauce” refers to the deeper explanation.)
Interesting, I hadn’t encountered that in any of my studying, just seen it in passing, but with my mechanical and other technical experience (limited though it is) I automatically interpreted “no moving parts” as a good thing. Another case where sloppy writers should have thought things through a little further.
ADDED: Anyone with an engineering background would have thought the same, my experience is limited but every engineering design book stresses reducing or eliminating moving parts as a good thing.
For anyone interested, Ferguson’s Engineering and the Mind’s Eye is a wonderful, comprehensive look at engineering design for general audiences.
I think the analogy holds. Hypotheses with too many “moving parts” can predict anything and so tell you nothing (they overfit the data). Hypotheses with too few moving parts aren’t really hypotheses at all, just passwords like “phlogiston” that fail to explain anything (they underfit the data).
Analogously a mechanism with too many parts takes a lot of effort to get right, and it’s weaknesses are hidden by its complexity. But if someone tried to sell you a car with no moving parts, you might be suspicious that it didn’t work at all.
As Einstein said, things should be as simple as possible, but no simpler.
What does it mean for a hypothesis to “have no moving parts”? Is that a technical thing or just a saying?
Not really either, it’s a neat way of saying that a hypothesis doesn’t actually explain anything: it doesn’t provide a deeper explanation for the phenomenon in question (this explanation is the “moving parts”).
A hypothesis allows you to make predictions; a good one will clearly express how and why various factors are combined to make the prediction, while a bad one will at best give the “how” without providing any deeper understanding. So a bad hypothesis is a little like a black box where the internal mechanism is hidden (sometimes, “no moving parts” might be better expressed as “unknown moving parts”).
This idea occurs in the sequences, but the best explanation of the meaning I can find there is (source):
(The “secret sauce” refers to the deeper explanation.)
Interesting, I hadn’t encountered that in any of my studying, just seen it in passing, but with my mechanical and other technical experience (limited though it is) I automatically interpreted “no moving parts” as a good thing. Another case where sloppy writers should have thought things through a little further.
ADDED: Anyone with an engineering background would have thought the same, my experience is limited but every engineering design book stresses reducing or eliminating moving parts as a good thing.
For anyone interested, Ferguson’s Engineering and the Mind’s Eye is a wonderful, comprehensive look at engineering design for general audiences.
I think the analogy holds. Hypotheses with too many “moving parts” can predict anything and so tell you nothing (they overfit the data). Hypotheses with too few moving parts aren’t really hypotheses at all, just passwords like “phlogiston” that fail to explain anything (they underfit the data).
Analogously a mechanism with too many parts takes a lot of effort to get right, and it’s weaknesses are hidden by its complexity. But if someone tried to sell you a car with no moving parts, you might be suspicious that it didn’t work at all.
As Einstein said, things should be as simple as possible, but no simpler.