Do you agree with Sherlock Holmes?

In The Sign of Four, Sherlock Holmes told Watson,

… when you have eliminated the impossible, whatever remains, however improbable, must be the truth

Do you agree?

I don’t agree…because from whatever remains, there may be several possibilities, but many may not be “the truth”.


But, logically, only one of those possibilities IS “the truth.” The others are all false, and thus impossible (because what is not the truth cannot possibly be the truth).

Suppose we ask, “who shot JR?” That question has only one possible answer (he was shot once). If we know for sure that only five people had opportunity, and we eliminate four of them as impossible, the last must be the shooter (even if Victoria Principal (as Pamela Barnes Ewing) is highly unlikely).

This is not a trick question. I’m not gonna pull out an Agatha Christie “And Then There Were None” twist. Assume it is a question of classical logic with no tricks or twists. All possible options are on the table, and all but one are positively and absolutely eliminated. The remaining option might seem absurd, but it MUST be true (such as the absurdly unlikely solution in Edgar Allan Poe’s Murders in the Rue Morgue).

In a quantum physics world, if we open the box containing Schrodinger’s cat, and observe the cat to be alive, it means it cannot be dead (and vice versa). Everything is plainly on the table, and there is no uncertainty. (Fun fact: Erwin Schrodinger developed the dichotomy of his famous cat to refute the “absurd” notion of uncertainty in physics. It was a reductio ad absurdum argument that has become the standard teaching model of the Copenhagen interpretation of Niels Bohr, so it completely backfired on Schrodinger).

There’s no trick in this question. It’s a flippin’ obvious question with a flippin’ obvious answer. But the answer has logical implications.

I voted ‘no’ thinking along similar lines to daddygirl.
Perhaps it’s semantics.
I thought of a hypothetical question? who drove to mom’s birthday party?
If I and each of my siblings say “I did”, we have five truth possibilities.
If one of us was actually home sick, then we have one impossibility and four individual true statements.

I think people are suspecting some kind of trick here, but someone would have to prove to me how this statement is not true. It is very simple. The Dallas reference dates you though. :wink: Funny, considering that if you had made some Aquinas reference it would not.

Agreed. But, unless driving was shared, you have only one driver (one actual truth).

My question presumes that all non-facts (people who did not drive) are known with absolute certainty, and only one possible fact (the actual driver) remains, even if the one possible fact is highly unlikely (perhaps a six year old child).

Again, it is NOT a trick question. The answer has other implications that I have not stated here, but the question itself is NOT a trick question.

For the purposes of this thread, I’m just trying to ascertain the level of philosophical (logical) awareness of people in this Forum. I have stated this.

What I am REALLY asking (but the answer STILL has further implications that I have not yet explored) is if we open the box containing Schrodinger’s cat, and we see that the cat is alive, can we conclude that the cat is alive? The cat is either alive or dead. If the cat is alive, it cannot be dead. If the cat is dead, it cannot be alive.

Sherlock Holmes would say that a living cat precludes a dead cat (even if the conditions in the box made surviveability highly unlikely). There are only two possible outcomes of opening the box - the cat is alive, or the cat is dead. No matter how unlikely is the possibility that the cat survived, Holmes would say that evidence of a living cat invalidates (makes impossible) a dead cat.

It is NOT a trick question. My question is a precursor to another thread that I intend to open, but I want to gauge Catholic reaction to this question before I proceed. It is NOT an attempt at a scientific survey, because I have already said that I agree with Holmes. If anybody can forward a logical disagreement then I would be interested. But if you think I am trying to trick you then you are wrong.

I’m working up to an Aquinas reference (the unmoved mover), but I intend to frame it in a more modern philosophical and scientific context. I wasn’t actually gonna mention Aquinas in the process, but I think you have discerned the philosophical root of my intent. But, first, I need to understand what I might expect here from a purely philosophical discussion.


Or, to restate Holmes in the syntax of logic (such as used in computer science),

If A is (B xor C)
and not B
Thus A is C

XOR is an unfamiliar logical construct to many - it is “exclusive or,” meaning “this OR that but NOT this AND that” (whereas logical OR includes both possibilities). XOR is the logical construct used when two options are mutually exclusive (the cat is either dead or alive).

If anybody can forward a logical disagreement then I would be interested. But if you think I am trying to trick you then you are wrong.

but you did not accept earlier logical arguments as logical (one of the first three comments)

anyway Holmes is wrong logically. possibility is not truth. when you eliminate all impossibles you are left with only the possibles.
it is possible for me that I WILL GO TO MASS TODAY does not logically constitute a truth that I WILL GO TO MASS TODAY.

Therefore since it is possible for me to vote YES for Holmes, I will prove him wrong by voting NO.

But Holmes is a detective, not a psychic. He only cares if you DID go to Mass today.

Either you did, or you did not. Holmes is not a theologian, and doesn’t care if you arrived late (or just HOW late you arrived), or if you fasted, or anything else.

Everything that Holmes knows is known to everybody. He ALREADY knows if you went to the such-and-such Mass (or neglected Mass altogether). He doesn’t care. Everything that CAN be known is already known. There is only ONE POSSIBLE alternative. It might be staggeringly unlikely. But Holmes (and Poe) think it is the only alternative to a corpus of impossibilities.


… when you have eliminated the impossible, whatever remains, however improbable, must be the truth

The impossible does not need to be eliminated. The impossible is eliminated by definition. Whatever remains must contain the truth, but, the statement is completely trivial.

A philosopher! Finally!

Whatever remains must contain the truth, but, the statement is completely trivial.

Awww. Philosophical truth is trivial?

heyyyy. let’s stick to logic here. I think you should re-evaluate the statement: should it be WHATEVER REMAINS MUST BE THE TRUTH or WHATEVER REMAINS MUST CONTAIN THE TRUTH?

As my siblings and I live in separate homes, we would still have multiple drivers.

I do agree that driving and not driving were the only options we could choose in my hypothetical case.

For me, things got messy in the Sherlock Holmes question with the shift from impossible to truth.
In a binary, I would oppose impossible with possible.

I’m looking forward to learning from your thread.:slight_smile:

Yes, I can see that, but it gets messy to state it from that direction and maintain the logical rigor. You would need to say:
Once you have eliminated all but one possibility, the remaining possibility, no matter how improbable, must be the truth.
I like Doyle’s approach better - it has a nice cadence. And it maintains logical rigor, because, after all, once a possibility has been eliminated, it becomes an impossibility. Something cannot be simultaneously possible and impossible.

I hesitated answering the poll when I first saw it posted. Then, I decided to say yes. Now, I’m having second thoughts, and wish I had answered it with ‘but’. If we were talking strictly about logic from a scientific point of view, then I would probably agree that he was correct. But, this is CAF, and religion doesn’t always follow strict logic. I would have to say that nothing is impossible with God, so that statement might not be as simple as it seems.

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