The Reasons Why Michael Myers never Speaks/Talks

I believe that John Carpenter wanted to represent Myers as a force of nature..something that cannot be reasoned with, overcome..just survived. In the opening of the first “Halloween”, you may notice as a child he never spoke just before or after the murder of his older sister…..I could hazard a guess he was selective mutism - he simply doesn’t want to speak

In order to make him mistique and inhuman the script writers had to resort to mute Michael. It is not explained why he doesn’t talk except that he just stopped.