With the slippery slope the person will not take an action or let it occur, because s/he believes that this will lead inexorably to a bad end. This is likened to starting to walk down an icy hill.
The classic slippery slope is a single, continuous slope. An alternative is the slippery stairs, with the downward trajectory involving a series of separate stages.
Elements:
(1) all or nothing thinking - once something is started then it is impossible to stop.
(2) a means to gain control over something terrifying
Examples:
(1) smoking marijuana eventually leads to heroin addiction
(2) kicking a cat leads to serial killing
Whether or not a situation will lead to catastrophe depends on a careful and realistic analysis of the situation.
(1) Is there a system of checks and balances in place?
(2) What appear to be the other person's intentions?
(3) Are the concerns justified?
(4) Am I being objective and realistic?
(5) What has happened previously?