The substantial factor test to determine proximate cause has been stated to be the following:

"If two forces are actively operating, one because of the actor's negligence, the other not because of any misconduct on his/her part, and each of itself insufficient to bring about harm to another, the actor's negligence may be found to be a substantial factor in causing the harm.Nevertheless, if the harm sustained by the other would have occurred with or without the actor's negligent conduct, then the actor's negligent conduct is not a substantial factor in bringing about the harm to the other. If the actor's conduct is a substantial factor in bringing about harm to another the fact that the actor neither foresaw nor should have foreseen the extent of the harm or the manner in which it occurred does not prevent the actor from being liable.

1) What is the difference between this test for proximate cause and the test articulated by the Court in Palsgraf v. Long Island Rail Road Co.?

2) Regardless of the which test is used to determine proximate cause, what other form of causation is needed in any successful claim of negligence?