Rosenstock-Huessy's Law of Technology

All technology expands the space, contracts the time, and destroys the working group.

Sattingler's Principle

It works better if you plug it in. If it still doesn't work, switch it on.

Ninety-nine Rule of Project Schedules

The first ninety percent of the task takes ninety percent of the time, the last ten percent takes the other ninety percent.

Grosch's Law

Computing power increases as the square of the cost. If you want to do it twice as cheaply, you have to do it four times as fast.

Computer Rule

To err is human but to really foul things up requires a computer.

Lubarsky's Law of Cybernetic Entomology

There's always one more bug.

Gallois's Revelation

If you put tomfoolery into a computer, nothing comes out but tomfoolery. But this tomfoolery, having passed through a very expensive machine, is somehow ennobled, and no one dares to criticise it.

Westheimer's Rule

To estimate the time it takes to do a task: estimate the time you think it should take, multiply by two, and change the unit of measure to the next highest unit. Thus we allocate two days for a one-hour task.

Peers's Law

The solution to a problem changes the problem.

Gilb's 1st law of unreliability

Computers are unreliable, but humans are even more unreliable.

Gilb's 2nd Law of Unreliability

Any system which depends on human reliability is unreliable.

Gilb's 3rd Law of Unreliability

Undetectable errors are infinite in variety, in contrast to detectable errors, which, by definition, are limited. Investment in reliability will increase until it exceeds the probable cost of errors, or until someone insists on getting some useful work done.

These rules were coined by Thomas Gilb, a systems engineer.