Saturday, April 21, 2012

Homeless Holmes, Case One

One of the most annoying repetitions in all literature is Sherlock Holmes' insistence to poor Dr. Watson and others subjected to his supercilious intellect that he is engaged in "deduction" when tracking down criminals or analyzing a crime scene.  What he's actually doing most of the time is "induction."  So instead of "deducing" things from clues and appearances,  he's "inducing" or "inferring," a necessary part of the scientific method.

Here's the difference,  illustrated in an easy example I used to give students (Apologies to professional logicians and philosophers of science):  Deduction is a logical inquiry in which the conclusion is certain, given the validity of the premise.   Take a guy who's always frantically searching for his car keys before work.   Accept the truth of the following premise-- his loving wife constantly reminds him that his keys can always be found in one of three places:  
     A.  Resting on the cluttered dresser top.
     B.  Hiding beneath the coins in his trouser pockets.
     C.  Dangling in the doorknob outside.
On a given morning the frantic boob establishes--with wifely aid--that the keys are neither A. Resting on dresser, nor B. Hiding in trousers.   "Huuunnnny . . .????" loving wife coos, as music starts mocking "wah wahs" and audience starts tittering. . . Cut to a shot of keys dangling in doorknob, rocking slightly in snowfall . . . Audience ROARS.

Deduction is entirely a matter of symbol manipulation, which is why computers seem so smart.

However, in one episode the boob sheepish rolls his eyes at loving wife, opens the door . . . Audience gasps.

The key hole is empty.  The keys are missing.  And so is the boob's highly recognizable station wagon. 

Here is where induction comes in.  Induction requires real-world knowledge and intuition (forget about defining these terms).  In this case it seems pretty clear that the keys were taken and with them someone has stolen the station wagon.   After this obviosity is out of the way, students quickly catch on that lots of other things could have happened and plenty of classroom speculative fun ensues:  Loving wife is playing a joke;  Boobish Husband is playing a joke;  their son Bibby, who was only introduced in the third season and seemed to vanish thereafter, has returned and is playing a joke; aliens are playing a galactic fraternity joke . . . and so on.

From there it's easy to show how scientists and workaday stiffs have to use both induction and deduction constantly, just to make a cup of good cup of coffee or use a urinal.  Some computer scientists claim that machines like Deep Blue and the Jeopardy-winning Watson are so advanced that they're using induction--and that by extention humans are just extremely well-stocked fact machines and that all induction is really hyper-deduction . .. but that's all boring and academic and Sherlock Holmes is still a preposterous bore.

Actually, I still like Holmes and have to admit that saying "ladies and gentlemen, my powers of deduction have have never failed me.  I invite you to observe these two ostrich eggs as I drop them from the balcony onto Baker Street . . . Now!  What do you deduce?"  sounds better than "What do you infer?" or "How do you like that shit?" 
(A dusty old joke that I like has Holmes and Watson pursuing a criminal mastermind into the wilderness.   They camp out and after midnight Holmes shakes Watson awake.

"Watson!  Wake up!  Look up!  What do you deduce?"

Watson shakes off sleep and looks up.

"Go on, man!  Deduce!"

"Well," says Watson, I observe myriad stars, around which may revolve planets such as our own, where may reside creatures such as ourselves, scheming, planning, hoping, fearing . . ."

"Watson, you idiot! Someone has stolen our tent!)

All this is prelude to talking very briefly about a fun new game I've started playing, "Homeless Holmes."  To play,  you pick out a homeless person while standing in line somewhere or sitting in chapel.  Then you rub your stubbly chin reflectively, hiss a bit, click your tongue, and say to yourself, "Observing this poor fellow I deduce (yes, deduce!) . . .

Then you take in the guy's age (about 87, from appearances, although he might be 63 and just very fermented and sun-puckered);  his pink My Little Pony backpack mended with safety pins; the plastic bags strapped over his bare feet with rubber bands and the rubber flip-flops he's somehow slipped over the plastic bags; the thick yellow fungus infecting all nine fingernails (Caught that, did you?); the way he sings "Amazing Grace" by intoning the word "YEEP" in different registers . . .

 . . ."I deduce that this fellow was for some 30 years a leading authority on Great Horned Owls at a great Mid-western university and murdered a colleague with the very same garden trowel he displays on his braided hemp belt to obtain that station in life.  He now sits there, a ruined example to us all!"

Play again and again . . . and enjoy!


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