Analysis of information sources in references of the Wikipedia article "The Free Software Definition" in English language version.
The reason they are numbered 0, 1, 2 and 3 is historical. Around 1990 there were three freedoms, numbered 1, 2 and 3. Then we realized that the freedom to run the program needed to be mentioned explicitly. It was clearly more basic than the other three, so it properly should precede them. Rather than renumber the others, we made it freedom 0.
I [Matt Mullenweg] originally thought Stallman started counting with zero instead of one because he's a geek. He is, but that wasn't the reason. Freedoms one, two, and three came first, but later he wanted to add something to supersede all of them. So: freedom zero. The geekness is a happy accident.
