#7 - Still on the 'ledge (with a ledger, a pen, and an idea)

Salvete! (Latin for hello [to more than one person])

Let's keep at this and continue on post #6...

Let's say that you're sitting down at your desk. You have your eyes closed, a writing implement, and a something to write on (perhaps your trusty 'ledger?) You're thinking about what would happen if you jumped off a cliff... with a nylon rope tied around your waist (phew, you had me worried for a sec). But the cliff is over a pool filled with lots of hungry pirañas [Oh my god, *gulp*, you know how much I hate.... diacritical tildes! Why can't you just spell it 'piranha'?!? Then it will be less scary!] [NO!]. You want to know exactly how long your rope should be (knowing that the nylon rope stretches a bit with respect to a factor that is a quality of the rope) so you can just barely touch the top of the pool. Well, you do all these calculations and you logically deduce that your rope should be x meters long. Hooray! You just gained some knowledge. Not just any knowledge, a priori knowledge.

A priori (pronounced 'ah pre-or-ee') is an awesome word/phrase that describes reasoning or knowledge that proceeds from theoretical deduction as opposed to experience.

A priori comes directly from Latin and literally means, "from what is before."

Then there's you're little brother. While you're slaving away working to logically deduce knowledge and prove things to be true, he's outside doing just any old random thing - observing the stars, throwing objects in the air, digging for a passageway to China. Stupid brother, he's out doing all these things to see how they work, when you could just show him how they work using your pencil and your trusty 'ledger. He also has a 'ledger for some reason. You don't know why he needs it, he's just taking down any old notes, he's not doing any calculations or logical deductions - he's just writing down what he sees. When he observes a phenomenon regularly and repeatedly, he infers from these particular instances a general conclusion. You do have to concede, however, that his methods for observation are pretty scientific. He is quite good at inducing knowledge. Not just any knowledge, a posteriori knowledge.

A posteriori (pronounced "ah poh-steer-ee-or-ee") is another awesome word/phrase that describes reasoning or knowledge that proceeds from observation or experiences - empirical as opposed to theoretical.

A posteriori comes directly from Latin and literally means, "from what comes after." 

So one day you're all fed up with him and his non-deductive ways:

"Hey, little brother! Get over here!"

"Sure...what is it?"

"How can you honestly expect to gain knowledge while you're outside all day?"

"How can YOU honestly expect to gain knowledge while you're inside all day?"

"Hah, I've learned dozens of things in the last half-hour with nothing more than logical deduction!"

"Well, anything you learn from that, I can learn with nothing more than my senses and observations!"

"Oh yeah? Well how about this: I just showed that you would need exactly x meters of nylon rope to jump off that cliff down the road in order to exactly touch the top of the piraña pool! Show that with your precious observation!"

"You mean that ledge? KNOW Ledge?"

"Yeah I do..."

"Well, okay." And he smiles.

"Okay?"

"Okay." And he smiles some more.

Man this is getting interesting! Part 3 coming soon...

Certainly yours,

Quentin

P.S. Recently learned that 'a priori' and 'a posteriori' have alternate pronunciations I did not know about. Listen to them here and here.