Comment by jncfhnb

The problem as described does not specify his behavior. Only what happened. If all you know is that he opened a goat door you have learned nothing.

It could be that he always opens a goat door meaning you should switch.

It could be that he only opens a goat door if you picked the car and you should not.

It could be he only opens a goat door if you picked a goat and you should.

Probability cannot determine which of these is any more likely than the other. You have learned nothing.