Dictionary Definition
User Contributed Dictionary
English
Adjective
knowable- capable of being known, understood or comprehended
Antonyms
Extensive Definition
Fitch's paradox of knowability is one of the
fundamental puzzles of epistemic
logic, proposed by Frederic
Fitch in 1963.
Given that some truths are merely unknown,
Fitch's knowability paradox asserts the existence of other truths
that are unknowable. The paradox thus contradicts the widely
accepted knowability thesis, which states that any truth is, in
principle, knowable.
Description
Essentially, Fitch's paradox asserts that the
existence of an unknown truth is unknowable. It thus concludes that
it is impossible for all truths to be knowable unless all truths
are known.
An old children's riddle illustrates Fitch's
paradox: "What was the tallest mountain in the world before Mount
Everest was discovered?" The answer is "Mount Everest", because
despite everyone's ignorance of the fact, Mount Everest was the
tallest mountain in the world. Thus, prior to the mountain's
discovery, the following statement was perfectly true:
- An undiscovered mountain that will later be named "Mount Everest" is the tallest mountain in the world.
The paradox applies to many types of statements,
including ones about undiscovered scientific principles,
information about the future, and secrets yet to be revealed. If
the truth of a statement is unknown, it is impossible to know
whether a statement about its unknown truth is itself true. Thus,
some true statements are unknowable, i.e. not all truths are
knowable.
External links
- Fitch's Paradox of Knowability. Article at the Stanford Encyclopedia of Philosophy, by Berit Brogaard and Joe Salerno.
- Not Every Truth Can Be Known: at least, not all at once. Discussion page on an article of the same name by Greg Restall.