When you find yourself debating with someone that fundamentally disagrees with your reasoning, there are often many arguments one can use that will get you a lot of pushback. When it comes to logical fallacies this pushback is very well deserved, they are in fact fallacies and thus should not be used to bolster any claim one has. Barring those, however, one argument that I noticed which gets a disproportionate amount of heat is the "slippery slope" argument, to the point in which it too is often labelled a fallacy.
The slippery slope argument is a very simple one which I am sure we have all heard at some point. If we allow for gay marriage what's next?! Marriage between a child and a man?! Marriage between a horse and a woman?! It is MADNESS! It is a slippery slope which should not be ventured down to begin with! While I have chosen a very pedantic example which might lead you to consider it a fallacy, there is more nuance to the argument than that.
In online discussions I have noticed that there are two very large groups of people: the fans of the slippery slope, who will pull it out at any time if for a note of caution than for a real prediction of the future, and those who hate the slippery slope, who think that by simply labeling something as a slippery slope automatically invalidates the other person's objection to whatever topic is in discussion. While I tend to err on the side of not using the slippery slope argument, I do not think that it is entirely without merit.
In many cases, the argument is completely bogus. How does, for example, allowing two consenting adults of unspecified gender to enter into a contractual agreement in any way open the gate to a contract between an adult and someone, or something, which is unable to consent? It is absolutely ridiculous. There are also other, more insidious uses of the argument as well. For instance, there is the very popular opposition to changing the language of what it means to consent from "not saying no" to "agreeing (verbally or non-verbally) to engage in various acts, which can be withdrawn at any time". Many people (I'm looking at you too, Cenk) love to make sure that everyone knows that they would be totally against it if it somehow devolved into having to sign a legally binding contract, signed and witnessed, every time you want to touch a boob or make out. It is ludicrous, it is hyperbolic, and mentioning that you are against such an inflated and unrealistic potential scenario down the line every time consent and rape comes up in the discussion detracts from the point that rape culture is a serious societal problem. All of these cases lead me to want to reject the slippery slope argument whole-cloth as a logical fallacy, but certain events have made me hesitant to do so.
The slippery slope argument does hold merit under some circumstances, and that is when we talk about legal precedent. When a legal ruling is made, which does in fact open the door to taking things further to an absurd end, I feel that criticizing such a ruling on the grounds that it could lead to a slippery slope is fully justified.
Take, for example, the Supreme Court Hobby Lobby decision in favor of allowing the Hobby Lobby corporation to not cover certain contraceptives in their health insurance plan for their employees, based on the sincerely held religious belief on the part of its owners that these contraceptives are abortifacients.
Never mind the fact that their religious belief is in conflict with reality, as there is no scientific evidence that, for example, Plan B blocks implantation, but rather prevents ovulation, therefore the fertilization of the egg never occurs.
Never mind the fact that Hobby Lobby's retirement plan holds 73 million dollars in mutual funds with investment companies which produce actual abortifacients, a detail that did not lead the Supreme Court to find that this was not, therefore a "sincerely held" religious belief of theirs.
Nope. This ruling sets a legal precedent allowing for corporations to subvert US law, so long as such a law comes in conflict with its owner's sincerely held religious belief, regardless of whether or not the belief fits in with reality. Regardless of whether or not the sincerity of their claimed belief could be legittimately called into question given an inherent hypocrisy in the corporation's finances. All you have to do is claim it, and the language of this ruling would allow it.
To point out this is a slippery slope is not a fallacy, it's a fact.
Could a Christian Scientist who employs thousands of people deny them health coverage other than faith healing, because their sincerely held religious belief is that faith healing is the only thing that works, and that any other form of medicine is sinful?
Could an old school Chinese Buddhist only cover acupuncture and alternative herbal Chinese medicine, on the sincerely held religious belief that modern medicine is harmful and wrong?
If there is any language in this ruling that would prevent other such nonsensical religious beliefs from infringing on the rights of the employees the way that Hobby Lobby was allowed to do, please feel free to correct me.
Just because wingnut anti-choicers have been allowed to dominate the airwaves and normalize their opinions on contraception, that doesn't mean that this ruling applies only to them. The law is designed to be blind to popularity, blind to public opinion. The law allows any behaviour that fits within the letter of the law, not based on how many people subscribe to that belief. If someone, a member of an obscure religion from another country, came to the US and started a business, which became a corporation, and then it turned out that this person's sincerely held religious beliefs considered any kind of preventative health care (colonoscopies, breast cancer screenings, pap tests, mole checks, etc) was a sin against their god, this law would permit them to deny that coverage to their employees.
And this, my friends, is a true slippery slope, and it is called legal precedent.
To point out this is a slippery slope is not a fallacy, it's a fact.
Could a Christian Scientist who employs thousands of people deny them health coverage other than faith healing, because their sincerely held religious belief is that faith healing is the only thing that works, and that any other form of medicine is sinful?
Could an old school Chinese Buddhist only cover acupuncture and alternative herbal Chinese medicine, on the sincerely held religious belief that modern medicine is harmful and wrong?
If there is any language in this ruling that would prevent other such nonsensical religious beliefs from infringing on the rights of the employees the way that Hobby Lobby was allowed to do, please feel free to correct me.
Just because wingnut anti-choicers have been allowed to dominate the airwaves and normalize their opinions on contraception, that doesn't mean that this ruling applies only to them. The law is designed to be blind to popularity, blind to public opinion. The law allows any behaviour that fits within the letter of the law, not based on how many people subscribe to that belief. If someone, a member of an obscure religion from another country, came to the US and started a business, which became a corporation, and then it turned out that this person's sincerely held religious beliefs considered any kind of preventative health care (colonoscopies, breast cancer screenings, pap tests, mole checks, etc) was a sin against their god, this law would permit them to deny that coverage to their employees.
And this, my friends, is a true slippery slope, and it is called legal precedent.