What does "ought" mean?

When someone says you "ought to" do something - what does that mean?
It appears to be an incomplete sentence in that ought to should be accompanied by "or else" rather like "either X or." makes no sense

I suggest it by default means the following

"Or else I will not approval of your actions"
Or "you will be the subject of my disapproval"

And one can extrapolate any further meaning from your knowledge of the person saying it and how they care about the topic and whether you think their approval is worth anything and whether it signifies anything.

You don’t even have to find out about the event of course.

For example there are cases where I might say - "you out to be nice to your pet dog" but since I don’t know you I will never find out if you hurt it. BUT my purpose is to make you think of my disapproval and feel it (despite the fact I am not feeling it myself) if you try to hurt the dog.