When is the “slippery slope fallacy” really
a fallacy?
Welcome to Critical Thinking Scan, where we
look at how you can think about any faith-challenging
message and arrive at a biblical, logical
conclusion yourself.
I’m Patricia Engler and today, let’s look
at another type of potential fallacy, or faulty
form of reasoning, which creationists are
sometimes accused of using.
It’s called the slippery slope fallacy,
also known as the thin edge of the wedge or—I’m
not making this up—“the camel’s nose
in the tent.”
The idea is that slippery slope arguments
say one action or belief will inevitably
(or at least, very likely) lead to another and
another, with dire consequences.
For instance, “If you leave the gate open,
then the dog will escape.
If the dog escapes, it will attack the mail carrier.
If it attacks the mail carrier, then important
mail will be delayed.
If important mail is delayed, society will collapse.
Therefore, if you leave the gate open, society
will collapse.”
As you might have noticed, this type of argument
involves a series of “if-then” statements
stuck together, which we saw in Episode 46 is an 
argument structure called a hypothetical syllogism.
Logically, this is a valid structure, because
if the premises are true, the conclusion must be true.
However, the problem with slippery slope arguments
is that it’s sometimes hard to tell
how true the “if-then” premises really are.
WILL society collapse if the mail gets delayed?
That doesn’t seem likely.
Since it can be hard to say how certain some
“if-then” statements are, slippery slope
arguments aren’t usually meant to be deductive
arguments, which PROVE an outcome will happen,
so much as inductive arguments, which IMPLY
an outcome is likely.
So, slippery slope arguments are only considered
fallacies if the outcome isn’t necessarily
likely, given the premises.
There are two questions you can ask to help
discern how likely the outcome will be, and
therefore, how strong the argument is.
Question 1: How probable is each “if-then”
statement?
For example, how likely would the dog escape
if the gate were left open, and how likely
would the mail carrier be attacked if the
dog escaped?
The less likely the outcomes, the weaker the
argument.
Question 2 is “How many “if-then” statements are there?”
The longer the chain of events, the less likely
the final outcome can be, if each event has
an associated uncertainty.
For instance, if it’s only 50% likely the
dog would escape if the gate were open, and
50% likely that the mail carrier would be
attacked, then there’s only a .5 x .5, or
25% chance the mail will actually be delayed.
On the other hand, if you can show that each
“if-then” statement is highly likely or certain,
the resulting argument is inductively
strong, and therefore, not a fallacy.
Now, let’s see how this can play out in
the creation-evolution controversy.
In an article entitled, “Argumentation and
fallacies in creationist writings against
evolutionary theory,” which I discussed
in Episode 32, a research team suggested that
creationists use the slippery slope fallacy
when they identify the negative societal outcomes
that accompany widespread belief in evolutionary
origins, including rising rates of racism,
abortion and euthanasia.
So, IS this a fallacy?
Only if belief in evolution is NOT logically
consistent with these outcomes.
But, like you can learn from the linked resources,
multiple scholars have documented in detail
the direct links between belief in evolution
and outcomes including racism, abortion and
euthanasia, because if humans are merely evolved
animals, there’s no logical reason for humans
to have greater rights than any other evolved
animals.
If we euthanize spare animals, we should be
able to euthanize spare humans.
Naturally, not every evolutionist will want
to enforce this conclusion, but the point
is that it’s logically consistent with an
evolutionary worldview.
Like you can learn from the linked resources.
If humans evolved apart from God, then humans
are left to define morality, and even secular
scholars like former Yale Law professor, Dr.
Arthur Leff, have realized that truly defining
moral absolutes logistically doesn’t work
without God.
Of course, showing that evolution leads to
serious consequences doesn’t prove whether
evolution is false.
But it does show the societal importance of defending 
the truth of God’s Word, beginning in Genesis.
For more on how to think critically about
messages that challenge God’s Word, you
can access my other CT Scan videos packed
with tactics, tips and tools that helped me
as a Christian student in secular university.
Thank you for watching!
Hey – It’s Patricia here.
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