you should've known better than

[stau la bloc]

Hello,

I couldn't find an explanation for this expression with Google. Also, I've put the question on another forum and didn't get a satisfying answer.
From what I've seen, "you should've known better than..." is followed by something undesirable, a negative outcome, and the meaning is "you shouldn't have done that".
And still, from a paper dictionary I've learned that it means something like "you should've known that it would be better to (do something)", so it would be followed by a desirable outcome.
Could someone please explain how can I use it correctly?

Thanks in advance.

 

[Copyright]

You should've known better than to invest with him -- now you've lost all your money.
You should've known better than to marry her -- now you've lost all your money.
You should've known better than to take up photography -- now you've spent all your money.
You should've known better than to listen to my advice -- now you're really in trouble.

 

[Cagey]

[....]
And still, from a paper dictionary I've learned that it means something like "you should've known that it would be better to (do something)", so it would be followed by a desirable outcome.
Could someone please explain how can I use it correctly?
[....]

Copyright has given you excellent examples, despite the fact that he is warning you against taking his advice.

However, I am puzzled by what you say the book says. I can't think of any way that form of assertion would be followed by a positive outcome. The closest I can come to it is:

If you had known better than to invest with him, you would still have your money.
​

But we wouldn't usually say this that way, though it is grammatical and possible.

 

[Hermione Golightly]

"you should've known that it would be better to (do something)", so it would be followed by a desirable outcome.

This is a different construction from "you should have known better than to ..", despite the similarity. It is focusing on the option that wasn't taken, the better option

It is a combination of "It would have been better to have + past participle " and "You should have known that. (that = it would have been better) "


It would have been better to have invested with GoLightlys
You should have known that it would be/was better to invest with GoLightlys (than to invest in Lehmans)

You should have known better than to invest in Lehmans



HG

 

[stau la bloc]

Thank you all very much!
Note: the dictionary isn't exactly Oxford, so...