PLATO
Plato (428 – 347 BCE)
Founded the Academy in Athens in 387 BCE, specializing in
mathematics and logic
His philosophical thought covered metaphysics, ethics, and
politics, written in Dialogues which involved Socrates questioning
his students. Socrates (469-399 BCE) had mentored Plato, who in
turn mentored Aristotle (388-322 BCE).
His most well know text is The Republic, illustrating an ideal state
run by “philosopher-kings” who have total control, but are
benevolent rulers who have studied the “form of the Good.”
PLATO’S JUSTIFIED TRUE BELIEF (JTB)
Plato and his students/contemporaries were not only concerned
with acquiring knowledge, but with being certain that it was really
valid. Intuition or faith did not generate certainty for them –
certainty involved knowledge that could be both described and
communicated. It must also be absolutely convincing to any
reasonable people.
Plato had three tests for certain knowledge:
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Test One: You must Believe the Statement
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Test Two: Your Belief has to be True
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Test Three: Your True Belief must be Justified
Test One: Belief
It is nonsensical to suggest that you can call a statement true
without actually believing it.
Consider: It’s true that Ottawa is the capital of Canada, but I don’t
believe it. Does this makes sense? Would you call it “truth” if you
didn’t have the belief? Substitute the word “conviction” for
“belief”
Despite belief being an attitude of mind, not believing something
somehow affects its “truthiness” (thanks Stephen Colbert!)
Test Two: Truth
Plato was an ABSOLUTIST, and accordingly believed that there
was an objective reality that was independent of human perception
(and even understanding).
[A RELATIVIST would suggest that all things are influenced by
human understanding: There is no truth except that which human
beings manufacture as truth.]
Characteristics of Truth
a) Truth is public: Truth is the same for everyone – if
something is true it’s true for everyone; if something is
false it’s false for everyone.
b) Truth is independent of anyone’s belief – something can
be true even if everyone believes it to be false; something
can be false even if everyone believes it to be true.
c) Truth is eternal: A true statement is true now, always
has been true, and always will be true.
According to Plato’s JTB, despite having belief, if a statement isn’t
objectively true then it cannot be described as certain knowledge.
Test Three: Justification
Even if one believes a statement, and it’s objectively true, it still
has to be able to be justified before it can count as knowledge
according to Plato. There are four main systems that allow for
this:
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Logic (divided into deductive and inductive logic)
Empirical Evidence (observation) – relies on perception,
which can be fooled
Memory (generally reliable, but can also be fallible)
Authority (there are authorities we can generally trust, though
authority is not always right)
DISCUSSION QUESTIONS
1. How do YOU decide if you accept something as knowledge?
2. i) Select examples of one specific thing you have learned in
 History
 Science
 Mathematics
ii) Turn each piece of knowledge into a statement that can be
tested by the three tests for Justified True Belief.
iii) Subject your statement to the three tests.
iv) On the evidence of your tests, examine the validity of
Justified True Belief
3. What, for you, is an acceptable definition of the word
knowledge?
4. Are the three types of justification logic, empiricism, and
authority equally reliable? Put them in a hierarchy and attempt
to justify your hierarchy.
5. What are you claiming to know when you “know” a piece of
music?
6. What is the difference between someone saying “I am certain”
and “It is certain”?