Babies cry. It's a fact. Next to pooping and sleeping, it's what they do best.
Why they cry can be anyone's guess. They could be wet, hungry, tired, scared, confused, sick, or just need some attention. They can't talk yet, so crying is the closest thing to a language they have.
For the most part, it works. You hear your baby cry, you quickly try to figure out what's wrong and rectify the problem. Crying baby = bad. That's what we're instinctively taught.
But at what point do we stop listening to our instincts? When babies cry all night long unless you're holding them, should you be comforting them or do you need to give them some tough love?