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Sunday, 19 November 2023


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My dad was an engineer. This was one of his favorite sayings :)

To know and not do, is to not yet know.

In essence, if you know stuff but don't apply it, it's valueless knowledge. And possible less than valueless, because you'll be open to claims of hypocrisy - even if only by yourself.

An old favorite. Also no idea where it came from.

(Clearly the same line, but my version ends "they differ.")

The version of this that I hear early on is: In theory, practice will follow theory, but in practice it doesn’t.”

Practice is what works. Theory is how things might or should work. Ergo, they're different.

It is the Song of the Insufficiency of Human Struggling in The ThreePenny Opera.

You make a cunning plan, then another one (the theory), but in practice, both don't work.

It is so odd an expression—for a scientist or engineer that is knowledgable, that it created a knee jerk reaction in me.

Let me try. Of course they are the same, so I am sort of walking around it.

A theory for our discussion is an explanation, often expressed in rather general terms so as to explain seemingly different situations. If the theory does not correctly account for things, as they are done, usually we are not really understanding how the theory and practice relate in the given situation. So I would not say as a catch all phrase “theory and practice do not match”, or “do not follow one and another.” It is not usually the case that the theory is wrong—just that it was not understood sufficiently well by the person saying this.

People tend to be divided into three groups: thinkers, doers, and both; left and right brain, and both; or some other unfortunate labels. To properly make an assessment the individual must have both feet in both camps. That is simply the way some of us are hard wired—but unless you have both feet in both camp, you not capable of deciding if theory and practice are or are not in agreement.

It would be unfair to ask a person not sufficiently knowing about art, to say if a William de Kooning painting is art. I think many of us recognize there are areas we/another is insufficiently knowing, or insensitive to, or prejudiced in, to make a judgement. So how can a person who is not sufficiently knowing about science decide theory and practice don’t agree.

This was usually the case, but to cover more bases, if practice and theory are not the same, then consider:

— the theory is unknown by the person, or it is too complicated/not presented in proper way, or the person is in some other way unqualified to judge

— the theory has been modified or supplanted, in which case a knowledgable person knows this. If the theory is simply wrong, then we are saying the explanation is wrong. Perhaps it was someones hypothesis, or someones attempt a an explanation—but it was inadequate for any number of reasons. And for a test whether theory and practice are consistent—it is unfair to use a wrong explanation.

— the theory is incomplete, in which case again a knowledgable person knows this.

This is most common and mostly under appreciated. In a non-mature area in science (or any area, when we continue to refine things), where things are too complicated we develop a simple explanation (simplest theory, and knowingly [planned to be] incomplete)—properly called a model, and then we explain the observed differences from the simple model, and use these differences to refine the model, creating ultimately a more whole theory.
In photography, a photo every day of the environment [not in the tropics, so we may need to start by picking carefully, or various environments] would, on review, be tough to spot a trend—make a theory, devise a model. But if we group them into—those taken in appropriate 3 month periods, we find a pattern, and we have a refined observation: spring is cool and plants are developing, and so forth. We can develop a model, that the orbit and tilt of the earth are broadly responsible. That is our model. and then improve the model and ultimately have a working theory (or group of theories), by including all he other reasons for differences. But theory does not say it cannot snow in August. Nor is global warming wrong when there are several consecutive cooler years.

Never thought we'd be talking about praxis on TOP.

Sounds like the quote:
'Those who can, do; those who can't, teach'

The source of 'those who can't do teach'?

My favourite saying is:

'Never show a job half done to a fool or a child'.

( I'd add 'Client' to that list ).

They are the same only if the theory incorporates the empirical evidence

Praxis… had to look that one up. I thought it was an East German copy of something 😄…

I always tell my wife I wish to die one day before her.
But I secretly wish it to be one day after. That way I might finally get the last word in.

I have a theory that engineer types lack a sense of humour/humor.

It's kinda looking like theory and practice are the same.

That quote has been attributed, at various times, to Einstein, Yogi Berra, Richard Feynman, etc. Quote Investigator gives it to Benjamin Brewster. https://quoteinvestigator.com/2018/04/14/theory/

The source is George Bernard Shaw.

“No plan of battle survives first contact with the enemy.” That’s all you really need to know about theory / practice.

In practice, aphorisms are useless.

As others have pointed out, the ‘hard’ sciences are probably the exception here (although I guess everything eventually breaks down if you zoom in or out enough).

The sentiment is much more in line with Rand Scott Adams’ comment.

Everyone has a plan til they get punched in the face.
All models are wrong, but some are useful.
No strategy survives contact with the real world.

Two definitions of theory:
1) An idea or set of ideas that is intended to explain facts or events.
2) A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts.

A theory is thus a mental model to explain the behaviour of some system. All models are simplifications and thus wrong, but many are useful because they explain the system well enough, in a constrained space, for us to base our decisions on them.

In some cases we move outside of the space that the model describes well enough, or our requirements change and what was good enough suddenly isn't anymore. Then we come up with a different theory to either refine the first one or apply to the new space.

The non humorous version is thus: Sometimes theory and practice are close enough to be treated the same, in other cases not.

We can own a simply constructed tool and recognise its function. However, possessing a hammer and knowing it can be used to join two pieces of wood together with a nail or three, is just the start. Can’t be difficult? Only a head and a handle.

Needing to join several pieces of wood together and being given appropriate nails by the kindly neighbour who has recently re-roofed their house, our hero is ready to go.

However, the process is more challenging than expected. Hitting the nail head squarely is apparently impossible, while the pain due to magnetic fingers is an unpleasant surprise. Who knew, nails have a life of their own? They don’t go straight, or unexpectedly bend, or both simultaneously.

Going again to the neighbour for more nails, sympathy, and help with a Band-Aid, she explains how with practice she got better.

“Though not as good as the old man who came to help. Once the nail was positioned, he didn’t need to look, while knowing exactly when to stop so as not to indent the wood. He could and would nail and talk while maintaining eye-to-eye contact!”

Of course, especially in North America, this sometimes bloody and blistered learning curve can be avoided by buying a nail gun.

Re: 'Those who can, do; those who can't, teach'. I read an explanation for this quote, but don't remember where. At any rate it goes somewhat like this. "Those who can't teach" is the case in part because "those who can't", have tried, and erred, and learned, and tried again. So that eventually they get closer to 'do', but in the process, they learn a lot that others need to know, hence they teach.

Truthiness: In theory, Sir Bedevere the Wise knew the woman was a witch made of wood because she looked like a witch, dressed like a witch, had reportedly turned someone into a newt, allegedly floated like bread, apples, and very small rocks and was proven to weigh the same as a duck. In praxis…well, in praxis, Sir Bedevere did what made sense to him at the time. Sir Bedevere did what was customary and I assume that because she was found to be combustible, he was “proven” correct. :-)

I just finished reading "The Things We Make" by Bill Hammack, on the relationship between engineering and science, which parallels practice vs theory. Despite the common refrain that scientific enquiry leads to later practical uses in engineering, he points out that engineering can live quite happily without science, and for most of human existence engineering has *preceeded* science, not the other way around. Example: Huge structures like cathedrals were built (and are still standing) long before science came along.

Engineering needs rules of thumb that are shown to work empirically - practice. It doesn't care so much about *why* they work, which is the job of science, to provide that theory.

On a related note, at my alma mater Univ of Chicago, there was a line that went "That's all fine and good in practice, but how does it work in theory?"

The wit of the quote seems to be lost on many smart readers. The "in theory" predicate seems to be ignored, thereby distorting the meaning of the balance of the first sentence. "in theory readers would read and appreciate the full meaning of written dialog. In practice they don't."

It's relatively rare for an observable event in the real world to have a single unitary cause. (One of the skills of scientific experimenters is jiggering things around to minimize causes affecting the thing being measured in the experiment.)

Thus, real-world events don't always conform to theory that well. A falling object doesn't really behave in accordance with Newtonian physics -- here in the Earth's atmosphere, where air resistance is a significant factor. (Cheap school physics lab experiments are particulary prone to problems in this area!)

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