1. Justified True Belief Understand JTB Know the key definitions
Start to criticise the idea of JTB

2. What is in this Topic?
For this section of the course, you will need to know:
The difference between acquaintance knowledge, ability knowledge and propositional knowledge.
The tripartite view of knowledge.
Issues with the tripartite view of knowledge: the conditions are not individually necessary.
Issues with the tripartite view of knowledge: cases of lucky true beliefs (Gettier and Fake-Barn Cases) show that the justification condition should be strengthened, added to or replaced.
Responses to cases of lucky true beliefs:

3. What is in this Topic?
Infallibilism: the justification condition should be strengthened, and there should be a requirement for an impossibility of doubt (Descartes).
A ‘no false lemmas’ condition should be added.
Reliabilism: the justification condition should be replaced with ‘produced by a reliable process’.
Virtue Epistemology: the justification condition should be replaced with ‘acquired as a result of a person exercising their intellectual virtues’.

4. Definitions: Acquainted Knowledge
Acquaintance knowledge (knowing ‘of’) includes knowing a person, place, or thing because we have met the person/visited the place/experienced the thing. For example:
I know Sally because I have met her.
I know London because I visited there.
I know the sound of Beethoven’s 5th symphony because I have heard it.
I know the taste of coffee because I have tried it.

5. Importantly, acquaintance knowledge need not involve any capacity to express this knowledge in language. For example, I may know what Beethoven’s 5th symphony sounds like without being able to describe it or without knowing any facts about it.

6. Definitions: Ability Knowledge
Ability knowledge (knowing ‘how’ or practical knowledge) involves knowing how to do something. For example:
I know how to ride a bike.
I know how to make a cup of tea.
Like acquaintance knowledge, a person may have practical knowledge of how to do something without the capacity to express this knowledge in language. For example, I may know how to ride a bike without being able to express the details of what this knowledge entails (the details of how to ride a bike).

7. Definitions: Propositional Knowledge
Propositional knowledge (knowing ‘that’) is knowing that something is the case. For example:
I know that the earth orbits the sun.
I know that I had breakfast this morning.
I know that I am studying AS philosophy.
Unlike the other two types of knowledge, this type of knowledge can (at least in principle) be expressed in language; I can make statements about what the world is like. For example, when I make the statement, ‘I know that the earth orbits the sun’ I am claiming that this is a true fact about the world.

8. The Tripartite view of Knowledge

9. Plato: Meno
The distinction between true beliefs and knowledge is first discussed in Plato’s dialogue, the Meno. The character Socrates argues that:
“True beliefs are a fine thing and do all sorts of good so long as they stay in their place; but they will not stay long. They run away from a man’s mind, so they are not worth much until you tether them by working out the reason… Once they are tied down, they become knowledge, and are stable. That is why knowledge is something more valuable than right belief. What distinguishes one from the other is the tether”
Plato, Meno.

10. Plato: Meno
Thus, for Plato, knowledge is more certain than belief because it is ‘tethered’ by reasons or evidence.
In Plato’s Theaetetus he claims that ‘true belief accompanied by a rational account is knowledge’, or in other words, knowledge is a true belief that is supported by strong reasons or evidence.
So, the traditional view of knowledge is that it is a justified, true belief: to know a proposition these three conditions must be met:
The person must believe the proposition;
It must be true; and
The person must have justification for believing in it.

11. Tripartite View of Knowledge
The tripartite view of knowledge:
S knows that p if and only if:
S believes that p
p is true
S has adequate or sufficient evidence for p, or is justified in believing that p.
e.g.
Sally knows that the earth orbits the sun if and only if:
Sally believes that the earth orbits the sun (the ‘psychological’ or ‘internal’ criterion).
It is true that the earth orbits the sun (the ‘external’ criterion).
Sally is justified in believing that the earth orbits the sun because she read it in a reliable science journal.

12. JTB
These three conditions for knowledge are considered to be individually necessary for knowledge (each condition must be satisfied for there to be knowledge) and jointly sufficient (if all three conditions are satisfied then there definitely is knowledge).

13. Necessary and Sufficient Conditions
Its three conditions, taken together, are intended to be ‘equivalent’ to knowledge. So if someone knows some proposition, they should fulfil exactly those three conditions. And if they fulfil those conditions, then they know the proposition. The conditions are ‘necessary and sufficient conditions’ for their knowledge that p.

14. Necessary and Sufficient Conditions
The tripartite definition of knowledge claims that if all the three conditions it lists are satisfied – if you have a justified true belief that p – then you know that p. You don’t need anything else for knowledge; the three conditions, together, are sufficient. It also says that if you know that p, then you have a justified true belief that p. There is no other way to know that p, no other analysis of knowledge. So, it claims, each of the three conditions is necessary. If p is false, or you don’t believe that p, or your belief that p is not justified, then you don’t know that p.

15. Necessary and Sufficient Conditions
So the definition puts forward two conditionals: if all three conditions are satisfied, then you know that p; and if you know that p, then all three conditions are satisfied. This means whenever you have one, you have the other. Knowledge and justified true belief are the same thing. Justified true belief is necessary for knowledge (you can’t have knowledge without it), but it is also sufficient for knowledge (you don’t need anything else).

16. https://youtu.be/oRzLh9xGOVE