Why don't we have two nulls?

Question

I\'ve often wondered why languages with a null representing \"no value\" don\'t differentiate between the passive \"I don\'t know what the value is\"

Answer 1

In most programming languages null means "empty" or "undefined". "Unknown" on the other hand is something different. In essence "unknown" describes the state of the object. This state must have come from somewhere in your program.

Have a look at the Null Object pattern. It may help you with what you are trying to achieve.