Basically, Says who? applies to all judgement calls in the gray (and sometimes not so gray) range.  Anyone who has tried to raise a child knows that for every piece of expert advice, there is often an equally persuasive counterargument.  As with highly complex tasks, there’s no one right way to mother.  Of course your child should not drink Drano (all the experts agree).  But when an officious passerby tells you your one-year-old shouldn’t have a pacifier or that your five-year-old mustn’t play with dirty cans in the park, it’s time for says who?