January 30, 2008

Re: Software Engineering Programs Are Not Computer Science Programs

Written by David Lorge Parnas the article under that title was published in "IEEE Software", Nov/Dec 1999, and essentially says that computer science and software engineering need to be separated in the same way as theoretical physics is separated from its related engineering fields. For the sake of both. As far as the education goes at least.

He also advocates the mandatory accreditation of software engineering programs and points out the problems to be encountered. Among the problems mentioned by the author are the lack of knowledge how to teach and experienced staff.

Frankly, the article was a little tedious to me, biased by the magazine specifics perhaps. But just like the other works of this great man that I had a chance to read, it is truthful and inspirational. Although in the case of this article, the inspiration has driven me in a slightly unexpected direction.

And so I would like to criticize the article on the grounds that the analogy between physics/regular engineering and computer science/software engineering does not hold.

First, there is a historical difference. Between physics and its engineering fields, it all began with practice and experiment. The extreme case would be construction - people have been prototyping since probably 50 thousand years ago. Two thousand years ago selected craftsmen have already mastered wood, stone and iron construction. There was neither science nor engineering at that moment, all they had was observation and experience.

I am not an expert in history of science, but it seems plausible that same pattern repeated most of the time - experiments came first and the theory followed. To be sure, physics as a science is far ahead now setting up experiments that only a few understand, but at least at early stages practical considerations have prevailed.

Exactly opposite is true for computer science. What began as pure mathematical theory in 1930s couldn't even be supported by experiment until a decade later when some sort of electrical apparatus has been constructed. In fact, being a branch of mathematics, computer science didn't have to be supported by experiments in the first place.

The "mathematical" engineering therefore was not something that anyone practically required. All they needed was to speed up the calculations, and I seriosly doubt that anyone could see the consequences. As the story has it, at one time IBM predicted the computer world market to be in tens of installations. If it wasn't for semiconductors, software engineering wouldn't even be here today, but computer science would.

Over time, software engineering became an awkward crossover between mathematics and psychology, where people try to project mathematical abstractions onto real world. Remember how Knuth said: "I have only proved it correct, not tried it." The matter dealt with in software engineering is thus something that should work because it is theoretically perfect but doesn't work because we are not practically perfect.

Second, there is an economical difference. Software is intangible, software production does not respect political borders, it can easily be and is routinely outsourced. What would you say if a team of construction workers could fly from India with its own tools and materials to raise a house overnight ? Plus they would charge less and still get the job done with satisfactory quality. And they would not need to be certified. Similarly, if a doctor or a lawyer could consult over the Internet from a different country, and his services were just as good, wouldn't that nullify certification efforts ?

Besides, you can't strictly control telecommutable industry, you try to lock it down by regulations and it goes underground. And the last thing we need is the black software market in addition to a pirated software market. Besides, such regulatory inhibition of software engineering would hamper the scientific progress and thus have exactly the opposite effect to the desired.

You may try to enforce mandatory certification of products instead, but this brings in a totally different perspective and requires a definitive procedure of software quality assessment - something at least improbable at this moment.

Third, there is a natural difference. There is no laws of nature in software engineering.

Try hard as you may, you cannot build a house which levitates above the ground. Because physics provides its engineers with absolute laws - such as energy conservation law, thermodynamics laws or Newton laws. They all may be a reflection of some deeper principles, but in practice it is sufficient for an engineer to know that you are limited in energy and can't fight gravity. And this is not because a scientist said so, but because you simply can't.

Not the case with software. The world in which software lives is only restricted with hardware architecture. Von Neuman is literally the god of software and computer scientists are his prophets. But what absolute laws do they give to their poor engineers ?


The hardware has its restrictions, that's true, but it is all in capacity. It is physics that limits the hardware, the computer science does not impose any restrictions above that. It is as though it was possible to build a house with the only restriction in mind - that its size should not exceed that of a planet. You can even start building from the roof, and it doesn't have to touch the ground when it's done. It's all imaginary.

The lack of unbreakable laws leaves all the arguments about how software has to be build to a degree open-ended. But then, how could you certify an industry in which there is still no consensus on how to do the simplest thing ?

To conclude, I believe that computer science and software engineering are indeed different, so different in fact, they can be treated as totally unrelated. But the relationship between them is not the same as with physics and engineering, and it would be wrong to approach it with established (educational) practice.


wiz said...

But how one have to distinguish good programmers from bad?

Dmitry Dvoinikov said...

And you are suggesting that by their certificates shall ye know them ?

There is indeed a correlation between certification and the product quality, simply because to obtain a certificate you have to pass a few courses. In the same way there is a correlation between certification and trust the people have in an engineer (although in case with software such trust is often void).

On the other hand, mandatory professional certification is not about quality, it is about responsibility. As soon as an engineer is granted a license, responsibility is shared. The underwriting authority is to a degree responsible for his future actions, and he is obviously responsible too, but now he is going to be much more careful at a risk of losing his practice.

Dima said...

Not quite agree with you, Dima. Computer science has its own laws, recall the theorem on the undecidability of arithmetics. These laws however, I agree, have completely different nature compared to laws of physics.

Dmitry Dvoinikov said...

Different indeed, as though a designer of a desk lamp should be concerned about E=MC2.

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