Nominull comments on Rationality Quotes: January 2011 - Less Wrong

2 Post author: wedrifid 03 January 2011 05:24AM

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Comment author: Nominull 07 January 2011 08:10:32PM *  3 points [-]

I don't think this is really true (but have not been able to downvote anything for quite some time). You can have a functional understanding of how something works (if you do A to it it makes B happen) without having a model of how it works internally. This sort of modeling is what the "theory" practicalists disdain concerns itself with, and they may do well to ignore it.

Because we have limited computational abilities, we will often do better on non-novel problems by learning a few useful patterns than by deriving everything from the underlying model. There is a reason why in elementary-school math classes we do not just give the children the Peano axioms and say "have at it".

Comment author: RobinZ 07 January 2011 09:06:27PM 8 points [-]

Next paragraph in the book:

What is wrong with "Theory of Flight," from the pilot's point of view, is not that it is theory. What's wrong is that it is the theory of the wrong thing – it usually becomes the theory of building the airplane rather than of flying it. It goes deeply – much too deeply for a pilot's needs – into problems of aerodynamics; it even gives the pilot a formula by which to calculate his lift! But it neglects those phases of flight that interest the pilot most. It often fails to show the pilot the most important fact of the art of piloting – the Angle of Attack, and how it changes in flight. And it usually fails to give him a clear understanding of the various flight conditions in which an airplane can proceed, from fast flight to mush and stall. This whole book, and especially its first chapters, are an attempt to refocus "Theory of Flight," away from things that the pilot does not need to know about, and upon the things that actually puzzle him when he flies.

Comment author: Will_Sawin 10 January 2011 01:37:26AM 2 points [-]

The synthesis here is roughly: Practical experience in a sort of Giant Lookup Table fashion but has bugs and fails in certain situations. Theory may have limits, but its main flaw is that it includes many useless things. To help those with practical experience, you need an awareness of theory and an awareness of the bugs in practical experience.

Anecdotal evidence: Most of driving, I learned through practice and instruction. I learned to brake smoothly only after my dad told me the underlying physics.

Comment author: RobinZ 12 January 2011 10:46:50PM *  1 point [-]

Thinking it over, it's also a matter of extrapolation. From practice, you can effectively fit a curve to the behavior, but you don't learn what happens outside the domain where that curve fits - and so, when you stall the wing or lose grip on the rear tires, your reactions will be exactly wrong, because you're playing by rules that don't apply any more. And yes, you can learn to fit the point of switchover and learn to fit the behavior in the new regime, in time ... but if you crash, first, it will be very expensive.

Comment author: Will_Sawin 13 January 2011 01:00:45AM 1 point [-]

Agreed, both are advantages of theory.

Comment author: RobinZ 02 November 2012 05:52:50AM 0 points [-]

I would like to belatedly apologize for the terseness of my response - I realize now that I was basically punishing you for not hearing what I didn't say, which was wrong of me.

In point of fact, I think Langewiesche was not quite correct - you can do things well without theory. Look at control systems. What theory lets you do is predict which practices will do well. We don't give children the Peano axioms, but we try to make sure what we teach them accords with those axioms.

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