"You know the only people who are always sure about the proper way to raise children? Those who've never had any"

This quote by Bill Cosby talks to the problem of parenting and the lack of certainty that comes with it. It implies that those who have never had kids are the only ones who are sure about the appropriate way to raise them. This is since they have actually not experienced the obstacles and unpredictabilities that include parenting. It suggests that parenting is a hard and unforeseeable journey, which there is no one-size-fits-all technique to raising children. It also suggests that those who have had children are more likely to be available to various techniques and to be more understanding of the troubles that feature parenting. Ultimately, this quote functions as a reminder that parenting is a complex and ever-changing process, and that there is no one best method to raise children.