Why is punishment by itself not an effective way of learning?

Why is punishment by itself not an effective way of learning?

Review King’s (2014) “Operant Conditioning,” p. 192. Then address: (a) why is punishment by itself not an effective way of learning? (b) does physical punishment frequently lead to aggression? and (c) should parents use physical punishment with children? Support your ideas with 3 articles published in peer-reviewed research journals.