It would be nice if we always knew the morally right thing to do, if our choices and commitments were painted in stark black and white.
The slippery slope argument is an argument where one action is argued to start a chain of events that will result in undesirable consequences. Take, for example, the argument that "If gay marriage is allowed, then people will want to marry objects or animals." When is the slippery slope argument fallacious and when is it—if ever—compelling?
This video from Wireless Philosophy gives a helpful explanation of the slippery slope argument and how to avoid committing a logical fallacy. Watch it here: