The Torah forbids necromancy [Lev. 19:31 and 20:6,27; Deut. 18:11]. Yet King Saul goes to the witch of Endor, who brings up the dead prophet Samuel for him. Samuel responds:
Why have you disturbed me and brought me up? ... Why do you ask me, seeing that the Lord has turned away from you and has become your adversary? ... The Lord has torn the kingship out of your hands and has given it to your fellow, to David, because you did not obey the Lord and did not execute His wrath upon the Amalekites. That is why the Lord has done this to you today. Further, the Lord will deliver the Israelites who are with you into the hands of the Philistines. Tomorrow your sons and you will be with me; and the Lord will also deliver the Israelite forces into the hands of the Philistines. [1Sam 28:15-19]
What does traditional Judaism conclude from this story?
(1) That there is an afterlife, and that communication with the dead is possible, but God does not want us to attempt it?
(2) That necromancy is bogus and that the witch of Endor was a gifted ventriloquist? (But Samuel's prophecy was fulfilled.)
Do you have sources, particularly for (2)? As for (1), did the rabbis actually mention that episode as a proof of an afterlife?