So the, the researcher runs a preliminary trial on this new cardiac medication,
right?
And the trial comes back, well, inconclusive.
It, it failed to prove that the medication actually lowers blood pressure.
But then the researcher turns right around and concludes that the medication is
definitely completely useless.
That it, it simply does not work.
Classic.
I mean, that is, that is literally the first trap I used to fall for every single
time on Section Two.
It is a classic LSAT move, yes.
And, and what is happening logically there is what Carl Sagan famously summarized
as, you know, absence of evidence is not evidence of absence.
Or to put it in formal terms, the lack of evidence for the existence of something
does not necessarily prove that it does not exist at all.
Right, because, okay, if I say I checked my backpack and I,
I did not find my keys, that does not mean my keys were annihilated from the
universe.
It just means, uh, maybe I did not look in the side pocket.
Or maybe I left them on the kitchen counter.
Precisely.
But in casual, everyday conversation, we, we collapse that distinction all the time.
If a friend says, hey, is there any evidence that the new coffee shop on Fourth
Street is open yet, and you say, uh, no, I have not seen any proof,
your friend naturally hears, okay, it is closed.
We, we use no proof as a proxy for false.
Yes!
That, that was my exact breakthrough when I was studying!
I realized the test writers are constantly playing on our human cognitive bias.
In real life, if nobody has proven a claim, we practically treat it as fake news.
But on the LSAT, a complete lack of proof just leaves us sitting right at status quo
uncertainty.
We, we just know nothing new!
Exactly.
Status quo uncertainty.
You are, you are stuck in the middle.
Now, there are really two distinct flavors of this flaw that you have to watch for
on test day.
The first one is the simple version we just described: taking no evidence for X,
and leaping straight to therefore X is false.
Okay, and, and what is the second flavor?
The second flavor is a bit more subtle.
It is when an arguer takes one specific, terrible argument for X,
completely dismantles that flawed argument, and then concludes that X itself must be
false.
Oh, like, if a bad lawyer brings in a terrible, completely unreliable witness to
prove the defendant was at the bank at three o clock, and you show that witness is
lying, you have not proven the defendant was somewhere else!
You have only proven that particular witness is a liar.
The defendant might still have been at the bank!
Knocking down a bad premise leaves the conclusion unproven,
not disproven.
Unproven, not disproven.
I, I literally wrote that on a sticky note on my monitor for two months.
So how do we spot this in the wild under time pressure?
You want to look for what I call the sharp about face in the stimulus.
The premise section will be spending all its energy tearing down a single study,
or calling a expert biased, or pointing out a flaw in a survey methodology.
It is all about the weakness of the evidence.
Right, tear, tear down the study, attack the survey.
And then, boom, you hit the conclusion, and the author makes a dramatic jump from
this evidence is weak to therefore, this claim is categorically false or this
event cannot happen.
That about face!
It goes from, uh, we do not know, straight to, we know it is definitely not true!
That pivot is your signal.
And when you see that structural pivot, you immediately go to the answer choices
looking for abstract descriptions of that mistake.
LSAC loves phrasing it like, conflates a lack of proof for a claim with proof that
the claim is false.
Or, treats failure to establish a position as conclusive evidence against that
position.
They have like, five standard, super legalistic ways of saying the exact same
logical error, do not they?
They really do.
It is the same skeleton dressed in different abstract vocabulary every time.
Okay, so here is the practical test I used when I was stuck between two choices,
especially on those tough Level Four and Level Five Logical Reasoning questions.
I call it the test of replacement.
Tell me about the test of replacement.
You scratch out the author's dramatic, sweeping conclusion,
and you replace it in your head with, therefore, we remain uncertain,
or therefore, we do not know yet.
If that replacement conclusion actually follows logically from the premises,
then you know the author committed the Absence of Evidence fallacy!
Ah, that is brilliant, Nora, because if we do not know yet is the actual
legitimate deduction, then jumping to definitely false exposes the unearned gap
immediately.
Exactly!
If the premises only justify saying we do not know, but the author said it is false,
you have caught them red handed committing the flaw.
You just grab the matching abstract answer choice and move on in forty five seconds.
Forty five seconds.
Clean, repeatable, no drama.
And no overthinking.
Unproven stays unproven.