What purpose is Jonas expected to fulfill and what would be the consequences of his "escape"?
In the world of The Giver, when a person turns twelve years old, he is given his professional assignment. Jonas is chosen to be the Receiver of Memory, a special position that only one person may hold for life. In this society, there is no memory of war, famine, heartache, or joy. There is no concept of history or a time before now. All of those memories are kept by one person, and Jonas has been chosen to be that person.
The consequence of Jonas's escape from the society would be that whatever memories had been transmitted to him by the Giver would then somehow return to the people. The eNotes study notes remind us that the previous Receiver found the assignment too distressing. The Elders allowed her to be released, and "the five weeks' worth of memories had come back to the people, causing them much anguish. The outcome is remembered as a terrible failure." Imagine what it would be like to have no concept of pain, and then all of sudden being overwhelmed by images and feelings of pain.
Even though the Elders considered the release of memories to be disastrous, it is necessary for both Jonas and the people. The eNotes essay "Controversial Themes in The Giver" states that "the community needs its memories in order to heal itself; if members acknowledge both their pain and their joy, as well as the depths of their emotions, Jonas will be 'released' (not killed) from the huge burden of serving as the Keeper of Memory."