1. Computers are unreliable, but humans are even more unreliable.
2. At the source of every error which is blamed on the computer you will find at least two human errors, including the error of blaming it on the computer.
3. Any system which depends on human reliability is unreliable.
4. Undetectable errors are infinite in variety, in contrast to detectable errors, which by definition are limited.
5. Investment in reliability will increase until it exceeds the probable cost of errors, or until someone insists on getting some useful work done.
6. The only difference between a fool and a criminal is that the fool will attack a system unpredictably and on a broader front.
7. A system tends to grow in complexity instead of simplicity, until the resulting unreliability becomes intolerable.
8. Self-checking systems tend to have a complexity in proportion to their inherent unreliability.
9. The error-detection and -correction capabilities of any system serve as a key to understanding the types of errors it cannot handle.
10. All real programs contain errors until proved otherwise which is impossible.

Found in NetDummy Humor.