Why the Monty Hall puzzle is categorically 1/2 and not 2/3rds

[haruspex]

Prior to choosing the door, we KNOW that at least one of the doors we do NOT open will contain..a goat.
Knowing as well that Monty knows exactly which door, and then opens, adds us no new information.
Had Monty been ignorant, our prediction would become sufficiently skewed towards the "two goats unopened"-scenario (i.e, that we picked the CORRECT door to begin with!) that it would become irrelevant whether we switch or not.

Yes. Did I appear to be saying something different?

 

[Thecla]

One way of thinking adout it:
If you have chosen a door and Mr Hall opened a different door, so there are now two unopenned doors. If at this moment a stranger comes in off the street in the middle of the contest and sees 2 unopenned doors, the stranger's odds of picking the correct door is 50% But you as a contestant have more information than the stranger who came from the street. You know more- what door you picked and which door Mr. Hall openned- than the stranger. This helps a lot.

 

[DonAntonio]

One way of thinking adout it:
If you have chosen a door and Mr Hall opened a different door, so there are now two unopenned doors. If at this moment a stranger comes in off the street in the middle of the contest and sees 2 unopenned doors, the stranger's odds of picking the correct door is 50% But you as a contestant have more information than the stranger who came from the street. You know more- what door you picked and which door Mr. Hall openned- than the stranger. This helps a lot.

Well, ALSO the stranger knows what door you picked and what door M.H. opened as he sees two doors. The really important

point is that the contestant knows that a third door exists which was opened and was empty . This is what changes

the odds for the contestant in cpmparison with the stranger.

DonAntonio

 

[arildno]

Yes. Did I appear to be saying something different?

No.
Sorry for not making clear I made my own reformulation of the content of your post, inspired by it.