Fundamental assumptions of statistical mechanics

[Mayan Fung]

The assumption states that all states (or I shall say micro-states) are equally probable. This is the foundation where we construct our theories on entropy, different kind of distributions, etc.
Is there any explanation for this assumption? Or why did the scientists that time take this assumption? I mean what made them think this is so fundamental.

 

[Charles Link]

Perhaps the best reason for it is they found that it works. It's kind of an odd assumption, (IMO=in my opinion), and my instincts, perhaps yours also, would tell you that some states seemingly would be more likely to occur than others. It surprised me a little when I first learned the subject, and you are correct, that the entire subject is based on the premise of all states of the same energy being equally probable.