How do you know what you know if there is no "all know-er"?

Question

It's been said that "unless a person knows all things about everything that one can know nothing about anything." Let's say we know X, Y, and Z about the universe. The earth is round. The sun is a star. Your wife cooks good. But we don't know A about the universe. A tells us that X, Y, and Z plus everything else we know are all lies. How do you know your chair doesn't turn into a platypus when you leave the room? How can you trust your senses? It seems to be impossible to know anything unless there is an "all know-er" who reveals portions of his knowledge to us. My head hurts.

Answer 1

There once was a man who said "God,
Must think it exceedingly odd
If it turns out this tree
Just ceases to be,
When there's no-one around in the quad."

"Sir, your puzzlement's odd,
For I am always about in the quad
Therefore my tree
Will continue to be
Since observed by, yours faithfully, God."

(And variations)

Two old poems on the question of whether existence requires an observer. (also the "does a tree, falling alone in the forest..?)

The idea is classically attributed to Bishop Berkeley. (URL)

But I'm not at all sure that your first proposition holds.
The escape clause comes with the categories of approximate and provisional knowledge. In fact it may be safer to take all knowledge to be in some degree approximate or provisional or both.

"The earth is round"? Well, yes, but more accurately it's an oblate spheroid.

You can't trust your senses absolutely, because we appear to be able to generate illusions and paradoxes and mistaken impressions. But most of the time, for most purposes, they do pretty well. The same with our ideas, or we'd rapidly starve from trying to eat things that weren't food. "What is food?" is a question for whole careers of whole groups of scientists, but on a day to day level, it's the stuff we find in the food department of a supermarket.

I recently drove my car to Cambridge. I'm not sure I could rigorously prove the existence of Cambridge, or the road, or my car (or "I"?). But the crude idea seemed to work pretty well. I got to what I thought of as Cambridge.

We appear to have enough knowledge about the universe to build silicon chips, computers, lasers... That's evidence of pretty good approximate knowledge, even if you might hear a scream or two if you go into a physics department and ask "What is an atom?"

It isn't in the sense that Douglas Adams intended it, but the world can be managed using "Clearly defined areas of doubt and uncertainty."

And yes, the possibility that everything is a computer simulation is not ruled out, but how would that change your day-to-day decisions? (URL)

Answer 2

Of course you can't be disproved. Your head hurts because there are too many things that CAN happen. All things being equal, we have only two choices:

1. Believe everything that CAN happen.
2. Believe only that which DOES happen.

(1) leads to insane people with delusions, as well as religious fundies

(2) leads to scientists, psychologists, and healthy humans.

In the final analysis, we achieve happiness by believing what's in front of us. It's normal. Since we are born with senses, it makes sense to use them for what they are best at. To sense the world, and gain whatever knowledge they can.

Answer 3

Hmm, interesting. I disagree with your premise...."unless a person knows all things about everything that one can know nothing about anything." I do not need to be told X, I can watch X happen.

Answer 4

Simple; accept that self does not 'know it all' now, but put first the being that does 'know it all'; God, who has 'known it all' from the beginning.

Answer 5

Good point. I guess you answered your own question... We don't know diddly! (Reminds me of The Matrix) lol

Answer 6

I always sucked at Algebra...

Answer 7

if there is no all knower then Stephen Hawking wins!