Introduction to philosophy, first slideshow.

1. What is philosophy?
an introduction
George Matthews
Spring 2016

2. What is philosophy?

3. What is philosophy?
Socrates
c. 469 – 399 BCE
The unexamined life is
not worth living.

4. What is philosophy?
Socrates
c. 469 – 399 BCE
The unexamined life is
not worth living.
Socrates is often considered to be the father of
Western philosophy. He spent his life encour-
aging others to ask difficult questions about
their values, assumptions and beliefs. He was
executed for “corrupting the youth” by teaching
them to ask similar questions.

5. What is philosophy?

6. What is philosophy?
! Philosophy is the attempt to understand the nature of
reality and the significance of our lives based on the
application of critical reasoning to our deepest and most
general beliefs.

7. What is philosophy?
! Philosophy is the attempt to understand the nature of
reality and the significance of our lives based on the
application of critical reasoning to our deepest and most
general beliefs.
! Science tries to classify, explain and predict phenomena in
the world.

8. What is philosophy?
! Philosophy is the attempt to understand the nature of
reality and the significance of our lives based on the
application of critical reasoning to our deepest and most
general beliefs.
! Science tries to classify, explain and predict phenomena in
the world.
! Religion and the arts tell stories that provide meaning for
human life in a larger context.

9. What is philosophy?
! Philosophy is the attempt to understand the nature of
reality and the significance of our lives based on the
application of critical reasoning to our deepest and most
general beliefs.
! Science tries to classify, explain and predict phenomena in
the world.
! Religion and the arts tell stories that provide meaning for
human life in a larger context.
! Philosophy seeks to identify, analyze and justify basic
assumptions we make in hope of finding general truths
about knowledge, reality and our social lives.

10. What is philosophy?

11. What is philosophy?
! Philosophy asks questions in a way that comes naturally to
children – it is imaginative, born of wonder, and the
mystery of life.

12. What is philosophy?
! Philosophy asks questions in a way that comes naturally to
children – it is imaginative, born of wonder, and the
mystery of life.
! But it employs methods that come naturally to lawyers – it
seeks to account for every last detail, employing analytical
thinking, careful definitions and rigorous logic.

13. philosophical questions

14. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?

15. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?
NOTE:

16. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?
NOTE:
! This is not a question about how we
in fact live, but a question about how
we should live.

17. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?
NOTE:
! This is not a question about how we
in fact live, but a question about how
we should live.
! Such normative questions challenge
us to give an account of ourselves,
our values, our assumptions.

18. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?
NOTE:
! This is not a question about how we
in fact live, but a question about how
we should live.
! Such normative questions challenge
us to give an account of ourselves,
our values, our assumptions.
! They encourage us to reflect on what
we might normally take for granted in
the attempt to justify our deepest
beliefs.

19. philosophical questions
Socrates
c. 469 – 399 BCE
How ought one to live
one’s life?
NOTE:
! This is not a question about how we
in fact live, but a question about how
we should live.
! Such normative questions challenge
us to give an account of ourselves,
our values, our assumptions.
! They encourage us to reflect on what
we might normally take for granted in
the attempt to justify our deepest
beliefs.
! Socrates’ question is a question in the
sub-field of philosophy called “value
theory” or “axiology.”

20. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?

21. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?
NOTE:

22. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?
NOTE:
! Descartes asked this question at the
beginning of the scientific revolution,
a time when old “certainties” were
revealed to be little more than
assumptions.

23. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?
NOTE:
! Descartes asked this question at the
beginning of the scientific revolution,
a time when old “certainties” were
revealed to be little more than
assumptions.
! Answering it requires a clarification of
what knowing in general involves as
well as different types of knowledge.

24. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?
NOTE:
! Descartes asked this question at the
beginning of the scientific revolution,
a time when old “certainties” were
revealed to be little more than
assumptions.
! Answering it requires a clarification of
what knowing in general involves as
well as different types of knowledge.
! Asking philosophical questions opens
us up to the risk of not being sure
how to answer them: do we really
know anything at all with certainty?

25. philosophical questions
Rene Descartes
1596 – 1650
What can I know with
any degree of certainty?
NOTE:
! Descartes asked this question at the
beginning of the scientific revolution,
a time when old “certainties” were
revealed to be little more than
assumptions.
! Answering it requires a clarification of
what knowing in general involves as
well as different types of knowledge.
! Asking philosophical questions opens
us up to the risk of not being sure
how to answer them: do we really
know anything at all with certainty?
! Descartes’ question is a question in
the sub-field of philosophy called
“epistemology” or “theory of
knowledge.”

26. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?

27. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?
NOTE:

28. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?
NOTE:
! Philosophical questions are often
much more general than questions we
normally encounter.

29. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?
NOTE:
! Philosophical questions are often
much more general than questions we
normally encounter.
! Science seeks answers to particular
questions about how things work
instead of such broad questions.

30. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?
NOTE:
! Philosophical questions are often
much more general than questions we
normally encounter.
! Science seeks answers to particular
questions about how things work
instead of such broad questions.
! In Heidegger’s view philosophical
questions may catch hold of us and
refuse to let us go, even if we may not
have a clear way of answering them.

31. philosophical questions
Martin Heidegger
1889 – 1976
Why is there something
rather than nothing?
NOTE:
! Philosophical questions are often
much more general than questions we
normally encounter.
! Science seeks answers to particular
questions about how things work
instead of such broad questions.
! In Heidegger’s view philosophical
questions may catch hold of us and
refuse to let us go, even if we may not
have a clear way of answering them.
! Heidegger’s question is a question in
the sub-field of philosophy called
“metaphysics.”

32. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

33. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

34. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

35. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

36. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

37. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

38. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

39. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

40. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

41. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

42. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

43. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

44. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

45. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

46. philosophy
Metaphysics
What
kinds of
things
exist?
How are
mind and
body
related?
Is there a
God?
Are we
really free?
Value Theory
(axiology)
Is beauty
in the eye
of the
beholder?
What
would a
just
society
look like?
What is
the right
thing to
do?
Logic &
Epistemology
When is
our
reasoning
reliable?
What can
we know?
What is
science
and how
does it
work?
a map of
the territory

47. the methods of philosophy

48. the methods of philosophy

49. the methods of philosophy
! Because philosophical questioning is open-ended and tries
to get to the heart of things, how to do philosophy and
whether we should bother are both open to question.

50. the methods of philosophy
! Because philosophical questioning is open-ended and tries
to get to the heart of things, how to do philosophy and
whether we should bother are both open to question.
! In general though, philosophers proceed by:

51. the methods of philosophy
! Because philosophical questioning is open-ended and tries
to get to the heart of things, how to do philosophy and
whether we should bother are both open to question.
! In general though, philosophers proceed by:
Identifying assumptions, unquestioned beliefs, underlying
pictures of how things are.

52. the methods of philosophy
! Because philosophical questioning is open-ended and tries
to get to the heart of things, how to do philosophy and
whether we should bother are both open to question.
! In general though, philosophers proceed by:
Identifying assumptions, unquestioned beliefs, underlying
pictures of how things are.
Developing arguments that might justify or refute these
assumptions, beliefs and pictures.

53. the methods of philosophy
! Because philosophical questioning is open-ended and tries
to get to the heart of things, how to do philosophy and
whether we should bother are both open to question.
! In general though, philosophers proceed by:
Identifying assumptions, unquestioned beliefs, underlying
pictures of how things are.
Developing arguments that might justify or refute these
assumptions, beliefs and pictures.
Seeking clarification by making distinctions, defining
terms, classifying positions.

54. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE

55. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
What is justice?

56. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
What is justice?
Socrates was not the first person to ask such
general questions. But he did notice how our
answers to these questions are connected with
many other beliefs, ideas and opinions we have.
He paid attention to the logic of our beliefs.

57. logic and the origins of philosophy
Thrasymachus
c. 459 – c. 400 BCE

58. logic and the origins of philosophy
Thrasymachus
c. 459 – c. 400 BCE
Justice is whatever
the powerful say it is.

59. logic and the origins of philosophy
Thrasymachus
c. 459 – c. 400 BCE
Justice is whatever
the powerful say it is.
Thrasymachus was a “Sophist,” one of a group
of professional teachers of rhetoric active dur-
ing Socrates’ lifetime. The Sophists claimed to
be able to convince anyone of anything and
often scoffed at the idea of finding the real
truth. Socrates considered them his enemies.

60. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE

61. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
Are you saying that
might makes right?

62. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
Yes I am.

63. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
But isn’t it also true
that even the powerful
can make mistakes?

64. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
Of course they
can!

65. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
But if they are mistaken,
might what they do or
demand go against their
own interests?

66. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
Yes . . .

67. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
So they might act
wrongly, even on their
own terms, if they act
based on their mistakes?

68. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
I guess so . . .

69. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
So there is a difference between
being powerful and being right
after all! And so might cannot
make right.

70. logic and the origins of philosophy
Socrates
c. 469 – 399 BCE
Thrasymachus
c. 459 – c. 400 BCE
Shut up!

71. logic and the origins of philosophy

72. logic and the origins of philosophy
! Socrates insists on a clear statement of assumptions.

73. logic and the origins of philosophy
! Socrates insists on a clear statement of assumptions.
! He draws out the implications of Thrasymachus’
definition.

74. logic and the origins of philosophy
! Socrates insists on a clear statement of assumptions.
! He draws out the implications of Thrasymachus’
definition.
! He demonstrates that these implications are inconsistent
with other beliefs that Thrasymachus holds.

75. logic and the origins of philosophy
! Socrates insists on a clear statement of assumptions.
! He draws out the implications of Thrasymachus’
definition.
! He demonstrates that these implications are inconsistent
with other beliefs that Thrasymachus holds.
! He is not after a rhetorical victory in a debate but is
convinced that open discussion following the principles of
logic will alone give us good reasons to believe what we
believe.

76. logic and the origins of philosophy
! Socrates insists on a clear statement of assumptions.
! He draws out the implications of Thrasymachus’
definition.
! He demonstrates that these implications are inconsistent
with other beliefs that Thrasymachus holds.
! He is not after a rhetorical victory in a debate but is
convinced that open discussion following the principles of
logic will alone give us good reasons to believe what we
believe.
! To find the truth we construct arguments in support of
our claims and then critically analyze these arguments.

77. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.

78. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
The premises are the
statements we use to
support our conclusion.

79. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
The premises are the
statements we use to
support our conclusion.
The conclusion is the claim we are
attempting to establish with this
argument.

80. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
How can we tell whether an
argument is any good?

81. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
How can we tell whether an
argument is any good?
! It must be valid: the
conclusion must logically
follow from the premises.

82. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
How can we tell whether an
argument is any good?
! It must be valid: the
conclusion must logically
follow from the premises.
! It must be sound: the
premises must be true.

83. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
How can we tell whether an
argument is any good?
! It must be valid: the
conclusion must logically
follow from the premises.
! It must be sound: the
premises must be true.
To check for validity we ask, “Can these premises be true
and this conclusion false at the same time?”

84. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
If it is true that all humans
are mortal . . .

85. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
If it is true that all humans
are mortal . . .
and it is true that Socrates
was a human . . .

86. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
If it is true that all humans
are mortal . . .
and it is true that Socrates
was a human . . .
Then it seems clear that the conclusion
must also be true.

87. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
So this argument is VALID.

88. logical analysis of arguments
All humans are mortal.
Socrates was a human.
Thus Socrates was mortal.
It is also SOUND since the premises are both true.

89. logical analysis of arguments
All humans are immortal.
Socrates is a human.
Thus Socrates is immortal.

90. logical analysis of arguments
All humans are immortal.
Socrates is a human.
Thus Socrates is immortal.
! This argument is also
valid, even though one of
the premises and
conclusion are clearly
false.

91. logical analysis of arguments
All humans are immortal.
Socrates is a human.
Thus Socrates is immortal.
! This argument is also
valid, even though one of
the premises and
conclusion are clearly
false.
! This is because IF the
premises were true, the
conclusion would also
have to be true.

92. logical analysis of arguments
All humans are immortal.
Socrates is a human.
Thus Socrates is immortal.
! This argument is also
valid, even though one of
the premises and
conclusion are clearly
false.
! This is because IF the
premises were true, the
conclusion would also
have to be true.
This argument is thus VALID, but UNSOUND since
the first premise is false.

93. logical analysis of arguments
All dogs are mammals.
My brother is a mammal.
Thus my brother is a dog.

94. logical analysis of arguments
All dogs are mammals.
My brother is a mammal.
Thus my brother is a dog.
! Suppose both of these
premises were true.

95. logical analysis of arguments
All dogs are mammals.
My brother is a mammal.
Thus my brother is a dog.
! Suppose both of these
premises were true.
! Does that mean that the
conclusion also MUST be
true?

96. logical analysis of arguments
All dogs are mammals.
My brother is a mammal.
Thus my brother is a dog.
! Suppose both of these
premises were true.
! Does that mean that the
conclusion also MUST be
true?
Clearly not! So this argument is INVALID, and because
of this it is automatically UNSOUND.

97. summary: argument analysis

98. summary: argument analysis
identify
argument

99. summary: argument analysis
identify
argument
Is it
valid?

100. summary: argument analysis
identify
argument
Is it
valid?
Can premises be true and
conclusion false?

101. summary: argument analysis
identify
argument
Is it
valid?
Can premises be true and
conclusion false?
INVALID
YES

102. summary: argument analysis
identify
argument
Is it
valid?
Can premises be true and
conclusion false?
INVALID
VALID
NO

103. summary: argument analysis
identify
argument
Is it
valid?
INVALID
VALID
Are
premises
true?

104. summary: argument analysis
identify
argument
Is it
valid?
INVALID
VALID
Are
premises
true?
no: UNSOUND
discard

105. summary: argument analysis
identify
argument
Is it
valid?
INVALID
VALID
Are
premises
true?
no: UNSOUND
discard
yes: SOUND
accept