1. How can I be sure I know something?

2. Learning Goal: By the end of the lesson students will begin to understand Plato’s definition of knowledge as true and justified belief

3. We all want our beliefs to be true, connect us to reality and not be mere opinions
But what is real knowledge?

4. Attaining knowledge
Our concept of knowledge as humans is first of all an attainment concept
For example, in Basketball we shoot in order to score. Shooting is the activity, scoring is the attainment intended.

5. In the life of the mind, we believe in order to know
So, like the basketball analogy, believing is the activity, knowledge is the attainment
Similarly, just as you can shoot a basketball and not score a basket, you can believe something and not have knowledge

6. What Is Knowledge?
Putting the question this way makes the question sound really hard. Here are three other ways to put it:
“What is it to know something?”
“Under what conditions is it true that a person qualifies as knowing that something is the case?”
An answer to this question will be a theory of knowledge.

7. Further Clarification of the Question ‘What is Knowledge?’
Three Ways the Word ‘Knows’ Is Used:
“Bob knows how to ride a bicycle.”
- Ability or practical knowledge
“Bob knows Cassandra”
- Acquaintance knowledge
“Bob knows that the earth is round.”
*Propositional knowledge, or knowledge by description
The theories of knowledge we’re looking at are about the third kind of knowledge – called knowledge that, or propositional knowledge (knowledge by description)

8. Plato on Knowledge The best known ancient Greek philosopher
Student of Socrates; teacher of Aristotle
Wrote about 23 philosophical dialogues
Famous doctrine: the Theory of the Forms
Western philosophy “consists of a series of footnotes to Plato.” A. N. Whitehead (1929)

10. How can I be sure I know something?
Plato and his colleagues came up with an answer to the question.
They said that for you to have certain knowledge (prepositional knowledge) you have to subject your knowledge claim (a statement of what you think you know) to three tests.

11. Test 1 You must believe the statement.
You can’t know something unless you believe it. I can’t know there is a God unless I believe that a God exists. Belief is necessary for knowledge it is part of the package deal.
Example: Knowledge of time
You must first believe your watch keeps accurate time in order for you to know whether or not it does.

12. Test 2 Your belief has to be true
Belief alone not sufficient for knowledge. You can believe something that is false.
Watch example: Your watch must keep time accurately. If it loses five minutes everyday, then you cannot know that it keeps time accurately your belief has to be true.

14. But… hold on… how do we know if something is true??
A great deal has been written on the nature of truth and we will examine it in this course… later 
Some philosophers believe there is a single, absolute objective truth, they are called absolutists.
Some believe that everything is subject to human interpretation, they are called relativists because they believe everything is relative to human understanding.
For our purposes of Knowledge as a True Justified Belief, we are going to go with the truth of the absolutist, as Plato was an absolutist.

15. The Absolutist Definition of Truth
Truth has three characteristics
Truth is public: truth is the same for everyone, that means that if the knowledge claim is true it is true for everyone, but if the knowledge claim is false it is false for everyone.
Consider the time example example…

16. Truth is independent of anyone’s belief
The knowledge claim may be false even if everyone believes it is true
The knowledge claim might be true, even if no one believes that it is
The truth of the statement “your dog is friendly” is independent of whether you think it is true or not

17. Truth is eternal
A true statement is true, was true and will always be true
Now we have a slight problem with the dog example. It might be that as your dog becomes older it changes and becomes “unfriendly,” but the current statement “your dog is friendly” is true for now, and will be true “for now” forever. Thus if your dog changes, the truth that he was once unfriendly will not change.

18. But back to Plato’s three tests for knowing
Recap
For knowledge, you must believe the statement, the statement must be true (public, independent, eternal) and finally…
Your true belief must be justified

19. Not this…

20. Why do we need justification?
Because you can believe something and your belief can turn out to be true, without you actually knowing the thing you believed…
Suppose you conjure up a belief that right now that Barak Obama is brushing his teeth.
Imagine you actually believe this, by force of sheer will. Suppose even further by the force of mere coincidence alone that Obama has just come back from a presidential lunch and just happens to be polishing his molars ready to rinse and spit.
You have the belief, and the belief happens to be true. Yet you had no real evidence it was true, you just got lucky. Philosophers deny that this is real knowledge. You did not know Obama was brushing his teeth, it was a wild coincidence, not an attainment of knowledge.

22. Knowledge = Justified True Belief
If you were looking at a live broadcast on CNN of Obama over his bathroom sink, brushing away, your true belief would be justified and thus you could count it as real knowledge. The question “how do you know?” would be answered by “I’m seeing it right now on CNN.” As long as CNN is a credible source…

23. What exactly is proper justification?
Good reasons to justify your beliefs, according to philosophers are as follows:
#1: Logic – logic is the basis for much of our knowledge an is an important justification for true belief

24. Good reasons for justification #2 Empirical Evidence
Empirical evidence is evidence gained by your five sense. What your senses, perceive, your sense perception, is one of the main sources of your knowledge of the world. Your five main senses are of course, sight, touch, taste, smell and hearing

25. Good reason for justification #3 Memory
Memory is notoriously fickle, but approached with care, memory is generally reliable

26. Good reason for justification #4 Authority
Of course we must be very careful who we accept as an authority, but in our everyday lives, we can accept that authorities do exist and we can trust them