David Parnas Quotes

Copy and paste is a design error.

One bad programmer can easily create two new jobs a year.

As a rule, software systems do not work well until they have been used, and have failed repeatedly, in real applications.

Artificial intelligence has the same relation to intelligence as artificial flowers have to flowers.

When someone builds a bridge, he uses engineers who have been certified as knowing what they are doing. Yet when someone builds you a software program, he has no similar certification, even though your safety may be just as dependent upon that software working as it is upon the bridge supporting your weight.

Requirements in mathematical language are no use unless they are easier to read than the code.

We must not forget that the wheel is reinvented so often because it is a very good idea; I've learned to worry more about the soundness of ideas that were invented only once.

Whenever anyone says, 'theoretically', they really mean, 'not really'.

Find the simplest model that is not a lie is the key to better software design.

With software products, it is usual to find that the software has major `bugs' and does not work reliably for some users... The lay public, familiar with only a few incidents of software failure, may regard them as exceptions caused by exceptionally inept programmers. Those of us who are software professionals know better; the most competent programmers in the world cannot avoid such problems.

Complexity is not a goal. I don't want to be remembered as an engineer of complex systems.

Many spend their time berating practitioners for not applying their method. We all need to disseminate our ideas, but most of our time should be spent applying and improving our methods, not selling them. The best way to sell a mouse trap is to display some trapped mice.

My judgment is that research in 'Star Wars' is going to fail, and I believe this so strongly that I'm willing to stake my professional reputation on this. I don't believe anybody is going to build this thing.

There are no standards for computer programmers and no group to certify them.

I have found that the reason a lot of people are interested in artificial intelligence is the same reason a lot of people are interested in artificial limbs: they are missing one.