One argument that supports the idea that the boys should be punished for the deaths of Simon and Piggy is that certain boys were fully aware that their actions and involvement in the deaths of the two characters. Every boy on the island participated in the murder of Simon, and Piggy was fully aware of his participation. Ralph and Samneric try to justify their actions and deny responsibility, but they are conscious of what they've done to Simon. Although the boys did not intentionally kill Simon, they are still guilty of voluntary manslaughter. Voluntary manslaughter consists of intentionally killing someone, but the killing is accompanied by additional circumstances. The most common type of voluntary manslaughter involves extreme provocation that induces rage or terror and is sometimes described as a "heat of passion" killing. Simon's murder would fall under this category. The boys were engaged in a ceremonial "war dance" and were in an uncontrollable frenzy. Their skewed perception and group-mindstate resulted in extreme violence. Each child on the island is liable for Simon's murder.
Roger is solely responsible for Piggy's murder. Roger is guilty of first-degree murder because his actions were pre-meditated. Roger had surveyed Castle Rock and knew the location of certain rocks that could be hurled at intruders. He thought about how he would commit the crime, and when the opportunity presented itself, he took action. The other boys on the island did not participate in Piggy's murder and were not liable. Roger acted alone, and would be guilty of committing first-degree murder. Hypothetically speaking, every child is guilty of manslaughter, and Roger is guilty of first-degree murder. They are all minors, and their sentencing would be difficult to determine.