By David Kelsey

• The word Philosophy :
– Philo-:
– sophy:
• Philosophy is the systematic investigation into the foundational concepts and principles of any subject matter .
–
A subject matter is:

•
So philosophy consists of the investigation of any subject matter .
• Understanding and Explaining a subject matter
• Example: Epistemology and knowledge

• The disciplines of philosophy include:
– Philosophy of religion:
– Philosophy of mind:
– Ethics:
– Metaphysics:
– Others…

•
A philosopher investigates the concepts and principles of any subject matter by use of:
– Conceptual analysis & Argumentation
•
Conceptual analysis is the analysis of concepts .
– Concepts :
• 2 definitions: words vs. ideas about a bit of the universe
• Examples :

– For something to be in the extension of (or to fall under) a concept:
• the thing must be an instance of the concept.
• The thing must fall under the concept
– If X is in the extension of a concept then…
–
Example:
• The concept knowledge picks out lots of things in the world…
–
The extension of any concept: defined as a set of things…

– A view on concepts : You might also think that concepts are abstract objects which are instantiated in our world.
– The picture:
–
–
LOVE KNOWLEDGE STUDENT
PHILOSOPHY SCHOOL
–
WORD TRUTH GRADE
– --------------------------------------------------------------------------------------------------
– L W P K T Sc G St
– W L P K T Sc St G
–
L P W K T Sc G St
– Above the line: abstract objects
– Below the line: our world.
– Where do concepts lie?
– Where is a concept instantiated, above or below the line?
– The extension of a concept then is just all of its instantiations.

•
If you will remember, one of the main tasks of philosophy is the analysis of concepts.
• To analyze a concept is
– An explanation
– A definition
•
To define a concept :
– Examples in the dictionary
• The philosopher’s task:
– To provide more detailed, full and clear explanations of concepts you can find in your what?

•
An Analytical definition is composed of a definiendum and a definiens .
– The definiendum: what is to be defined
– The definiens: what defines
• Form: the form of a definition is this:
– X =df _____
• Which is the definiendum and which is the definiens?
– For example,
• Knowledge =df true belief

• We can think of a definition as a set of necessary and sufficient conditions.
•
X is a necessary condition of Y if and only if (or iff) we cannot have Y without also having X.
– Oxygen and Combustion
•
X is a sufficient condition of Y iff X is all that is needed to get Y.
– Being born in the US and citizenship

•
X is both a necessary and sufficient condition of Y iff both
– 1) we cannot have Y without also having X &
– 2) X is all that is needed to get Y.
•
Example: knowledge as JTB

• So one of the main tasks of Philosophy : is to define concepts.
–
Defining concepts
: When defining philosophical concepts, we aren’t out to define them in any old way we like.
– Adequate Definitions : We want to find the correct or adequate definitions of our philosophical concepts.
– Co-extension : For a definition to be adequate the definiendum and definiens must be co-extensive.

• For a definition to be adequate the definiendum and definiens must be co-extensive.
• For the defiendum and definiens of any definition to be co-extensive it must be the case that:
– 1)
– 2)
– What is the extension of a concept?
• Example in knowledge as JTB…

•
To determine if a definition is adequate:
– determine if its definiendum and definiens are co-extensive.
– Is there any item in the extension of one that isn’t in the extension of the other?
– Example: Knowledge is true belief
• All Knowledge is true belief.
• All true belief is knowledge.
• Universal generalizations and counterexamples

•
A counterexample : a case that violates a universal generalization.
• If we define knowledge as true belief we just need one counterexample to show this definition inadequate.
– We need to find a case of knowledge that isn’t what?
– Or a case of true belief that isn’t what?
– A counterexample:
• The Belief Game:

•
Love : Say I define Love as a deep seated feeling composed of compassion & care which one can have for another human being.
– Can anyone find a counterexample to this definition?
•
We are looking for either:
– a case of love that isn’t ____________
– a case of having this feeling for another human which isn’t ______________
– Any thoughts?