Well we see this everywhere! If Viet Nam falls to the Commies, then so will Thailand, Malaysia and others.

On the other hand, if I allow you to eat Dairy Queen Blizzards and eat Big Macs all the time, you are gonna get fat is probably true.

"If we don't invade a nation that had nothing to do with 9-11, then the terrorists will be flooding the streets and stopping me from eating my quarter pounders with cheese!"

A real favourite of shallow thinkers of all political stripes, this is very common on RIA.

The arguments always go something like

"If we don't burn witches, pretty soon Satanism will be required in elementary schools," or

"If Michael Moore makes any more speeches at the Academy Awards, pretty soon we'll all be living on collective farms."

The slippery slope argument is commonly committed, especially in social and political debates. Sometimes when a person is giving certain reasons supporting a certain conclusion, he or she might claim that a particular event will set off a chain of events in which one event will lead to another. Reality is that many times there is insufficient evidence to suggest that such a scenario would play out. It is difficult to determine causality many times, and simply put, it is difficult for us to know the future and how certain actions will play out. The amount of outcomes always increases when there are more variables at play supporting a certain final claim.

This is the incorrect assumption that one event causes a chain of more alarming events. Example: If we allow the nurse to deliver the prescribed medicine, tomorrow we'll think its okay to allow nurses to prescribe medication without a physician. Note that deciding on the acceptability of dispensing aspirin does not actually imply the occurrence of more extreme behaviors or show acceptance toward nurses prescribing medicine. Thus, the fallacy in logic.

This should be evaluated on a case by case basis. To say If I shoot you in the face with this shotgun, you'll probably die, and if we're not careful, that could lead to a funeral and maybe even a burial or cremation is hardly a slippery slope. This is one to be careful about, as it's been my experience to see such an argument called out by some intellectual whistleblower as a slippery slope when the reality of the matter was that it was called such because said whistleblower had an agenda of his own and wanted to discredit any opposing arguments. These things do exist, but it requires a little game theory to provide a reasonable estimate of possible outcomes, not unlike the point about gambling made by JonTheMan.

Here's another one you see a LOT in political debate, right, left, lunatic fringe and dishwater center. If we cut down these trees soon we won't have any trees left! If we give homosexuals equal rights, pretty soon child molesters will be demanding equal rights too!

NPR did an interesting segment that featured a linguist who tracked the usage of the term slippery slope and whether it actually occured in any situation that it was predicted to. It did not. This arguement is the darling of anyone who just wants to get a debate over with when they can no longer back their opinion and I've seen it espoused by more than a few regulars here on RIA. It's also a favorite of Senator Santorum who likes to equate homosexual relationships with bestiality based on the slippery slope fallacy.

I'd say this is a way of making one argument seem more important then it actually is. However it is still not unknown for governments to institute gradual change over a period of time that will end in a radical change to the original society. Some schemes are part of a larger agenda, the issue here is recognizing which ones. For example: If a very financially paranoid person says I'm just going to play a few games of blackjack you probably have nothing to worry about, if a compulsive gambler says the same thing it is not illogical to assume he'll be broke by the end of the night.