1. Introduction to Philosophy Lecture 1-a What is philosophy? By David Kelsey

2. What is philosophy? The word Philosophy: –Philo-:means love –-sophy: means wisdom –Literally, Philosophy means Love of Wisdom. Philosophy is the systematic investigation into the foundational concepts and principles of any subject matter. –A subject matter is: a topic of discussion. –It is just a grouping of any number of related concepts, which we can discuss, study and argue about.

3. Explaining a subject matter So philosophy consists of the investigation of any subject matter. As a philosopher one tries to better understand a subject matter. –One tries to explain the subject matter: I might examine the subject of Epistemology: –I could explain that knowledge is something one can have. –When one has knowledge she holds a belief about whatever she is said to know. –When she has knowledge this held belief is true. –So I might explain that knowledge is true belief.

4. The disciplines of philosophy The disciplines of philosophy include: –Philosophy of religion: the investigation of concepts such as GOD. –Philosophy of mind: the investigation of concepts such as MIND and BRAIN. –Ethics: the investigation of concepts such as RIGHT, GOOD, and WRONG. –Metaphysics: the investigation of concepts such as EXISTENCE and PERSISTENCE. –Philosophy of mathematics: the investigation of concepts such as NUMBER, REAL NUMBERS and INFINITY. –Epistemology: the investigation of concepts such as TRUTH, KNOWLEDGE and BELIEF. –Philosophy of language: the investigation of concepts such as MEANING and REFERENCE. –Philosophy of science: the investigation of concepts such as SCIENTIFIC CHANGE. –Philosophy of BIOLOGY: the investigation of concepts such as EVOLUTION. –Philosophy of art: the investigation of concepts such as BEAUTY.

5. The tasks of philosophy 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 are really just words. Examples: ‘knowledge’, ‘student’ ‘love’ & ‘philosophy’. –You might think of a concept as an idea, which is about some bit of the universe. GALAXY: this concept is about certain groupings of millions or even billions of stars all linked together by gravity. LOVE: about a certain affectionate feeling that humans can have for other humans.

6. The extensions of concepts Concepts have extensions: –Certain things fall under a concept. –For something to be in the extension of (or to fall under) a concept: the thing must be an instance of the concept. –If some thing X is in the extension of a concept: the concept is instantiated in X. –The concept KNOWLEDGE: Picks out lots of things in the world: –Such as my belief that the Earth orbits the Sun (and my belief that the Earth is round, and my belief that the moon orbits the Earth, etc.) –In this case I have knowledge. My belief is an instance of knowledge and so is in the extension of the concept of KNOWLEDGE. –All of these instances of knowledge are in the extension of the concept of KNOWLEDGE. –The extension of any concept: a set of things in the world,each member of which is something in which the concept is said to be instantiated.

7. A view on Concepts –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 are all of the abstract objects like concepts. –Below the line is our world. Below the line is the Earth, and everything on the Earth and the planets and the solar system and the galaxies and so on. –Concepts are instantiated below the line. For instance, each ‘L’ depicts the concept of LOVE being instantiated. –The extension of a concept is just all of its instantiations. For example, the extension of LOVE is just all of the L’s.

8. Conceptual analysis If you will remember, one of the main tasks of philosophy is the analysis of concepts. To analyze a concept is –to explain that concept. –It is to define that concept. To define a concept: –Examples of definitions in the dictionary. –The dictionary is full of definitions. So you might think of the philosopher’s task as just: –To provide more detailed, full and clear explanations of many of the concepts you find in your dictionary.

9. Definitions A definition of a concept is composed of a definiendum and a definiens. –The deifiniendum is what is to be defined. –The definiens is what defines. For example, if we define KNOWLEDGE as true belief, KNOWLEDGE is the definiendum and true belief is the definiens. The form of a definition is this: –X =df _____ –Knowledge =df true belief –The definiendum: on the left –The definiens: on the right. Another way to think of definitions: –A Definition is a set of necessary and sufficient conditions. –In particular, the Definiens is a set of necessary and sufficient conditions for the definiendum.

10. 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. –If oxygen is a necessary condition of combustion: then we cannot have combustion without oxygen. If we have combustion we must have oxygen as well. To say that oxygen is a necessary condition of combustion is to make the logically equivalent claim that if there is combustion then there is oxygen. X is a sufficient condition of Y iff X is all that is needed to get Y. –If being born in the United States is a sufficient condition for US citizenship: then being born in the US is all that one needs to be a US citizen. To say that being born in the US is a sufficient condition for US citizenship, is to make the equivalent claim that If one is born in the US then she is a US citizen.

11. Necessary and Sufficient Conditions #2 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. So If being true belief is both a necessary and a sufficient condition for being knowledge then both: –1) one cannot possess knowledge without her also possessing true belief & –2) possessing true belief is all it takes to possess knowledge. –To say that being true belief is a necessary and sufficient condition of being knowledge is to make this logically equivalent claim: If something is true belief then it is knowledge & if something is knowledge then it is true belief.

12. Definitions and Necessary & Sufficient conditions So for any definition the definiens is a set of necessary and sufficient conditions for the definiendum. Consider: X = df Y –Y is a set of necessary and sufficient conditions for the occurrence or instantiation of X. –Substitute for X ‘Knowledge’. Substitute for Y ‘true belief’, then: The Form: ‘Knowledge = df true belief’ 1) one cannot possess knowledge without her also possessing true belief & 2) possessing true belief is all it takes to possess knowledge.

13. The goal of Philosophy: Finding Correct Definitions 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.

14. Co-extensiveness Co-extensiveness: For the defiendum and definiens of any definition to be co- extensive: –1) Everything that is in the extension of the definiendum is in the extension of the definiens & –2) Everything that is in the extension of the definiens is in the extension of the defiendum. For something to be in the extension of a concept: that thing must be an instance of the concept. If the definition of KNOWLEDGE as TRUE BELIEF is correct then: –Everything in the extension of KNOWLEDGE is in the extension of TRUE BELIEF and vice versa. –In other words, these concepts pick out the very same items in the world. –100 items of knowledge: if there were say 100 items in the extension of KNOWLEDGE those very same 100 items would be in the extension of TRUE BELIEF.

15. Testing definitions To determine whether a definition is adequate: we must determine if its definiendum and definiens are co-extensive. Question: is there is any item in the extension of one which isn’t in the extension of the other. Is our definition of Knowledge adequate? We must ask if –All Knowledge is true belief. –All true belief is knowledge. –These two claims are universal generalizations. They are said to hold in all cases without exception. –Counterexamples to generalizations: to refute a generalization then we need only a single counterexample.

16. Counterexamples: Knowledge A counterexample: a case that violates a generalization. –Counterexamples are exceptions to the rule. –Knowledge = df true belief: we just need one counterexample to show this definition inadequate. Counterexample #1: a case of knowledge that isn’t true belief. Counterexample #2: a case of true belief that isn’t knowledge. –The Knowledge game: I am asked to hold a belief and if it is true I get 100$. I am asked something I know nothing about: whether or not there is a black hole in the middle of the milky way galaxy. So I take a guess. I say yes. I get lucky and win the 100$. –Lucky guess: My belief is true but only in virtue of my lucky guess. –Do I have knowledge? No!

17. A counterexample to a definition of Love Defining Love: Say I define Love as a deep seated feeling composed of compassion & care which one can have for another human being. Find a counterexample: –a case of love that isn’t a case of having this feeling for another human or… –a case of having this feeling for another human which isn’t a case of love. Pets: What about Pets? Aliens: –Imagine an alien ship lands on Earth and out come a few very friendly aliens. –Could you love them?