The Unique way of representing the relationship existing between the subject and the predicate.

1. VENN
DIAGRAM
Humanities I- Logic

2. Venn Diagram
 the unique way of representing the
relationship existing between the
subject and the predicate
 John Venn- English mathematician
and logician
 Used two overlapping circles to
show whether or not the subject is
related to the predicate.

3.  the logical reason for using the two
overlapping circles is to present two
worlds of discourse which are the
world of discourse of the subject
and the world of discourse of he
predicate.

4.  The world of discourse of subject
is sometimes referred to as the
class S and the world of
discourse of predicate is referred
to as the class of P.

5.  Figure 1 may
represent any
class. Note that
this is blank or
void. It contains
nothing yet. It
does not represent
any proposition
yet.
Figure
1

6.  Figure 2 is a shaded
circle. It connotes a
nullification of a class.
 It may also mean that
within a class, nothing
exists.
Figure
2

7.  Figure 3 has an
“x” symbol inside
the circle.
 It means that
there is at least
one individual
representing a
class.
X
Figure
3

8.  Figure represents the
class of S and the class
of P.
 The standard form of
categorical syllogism is
represented by two
circles bound to each
other.
 These two overlapping
circles do not contain
anything yet.
Figure
4
S P

9.  Figure 5 presents the four
partitions in the class of
subject and predicate.
 Note that some of the letters
are underlined.
 The line below a certain
letter indicates that the part
is outside the circle f either
subject of predicate.
Figure 5
S P
SP SP SP

10.  The S P symbol indicates the
partition where the class of subject
is not part or outside of the class of
predicate.
 The symbol S P indicates the
partition where the class of subject
is also part of the class of
predicate.

11.  The symbol S P indicates that the
partition where the class of
predicate is not part or outside the
class subject.
 The last symbol S P indicates that
the partition where the classes of
subject and predicate do not exist
or outside both the circles of
subject and predicate.

12. Diagram of Four Categorical
Proposition (Examples)
 A: All birds are winged
creatures.
 Shading the entire
partition of S P will
give us the impression
that every S is P. The
shaded area means
that nothing is present
in it because the S is
Figure 6
S P

13. E: No soft drinks are hard
drinks.
 In figure 7, the partition
S P where the class of
the subject is part of
the class of the
predicate is shaded.
 This connotes that
there is nothing existing
between the subject
“soft drinks” and the
predicate “hard drinks”.
Figure 7
S P

14. I: Some students are very
honest.
 Figure 8 shows an “x”
mark in the partition of
S P.
 This means that there
is something inside it
that belongs to the
class of subject
‘students” and also to
the class of predicate
“very honest”.
Figure 8
S P
X

15. O: Some motorcycle riders are not
wearing helmets.
 In figure 9, the “x” mark is
outside the domain of
predicate term. It
occupies the partition S
P.
 This connotes that there
is something existing in
that area that is not part
of the domain of the
predicate term.
Figure 9
S P
X

16. Exercises: Venn Diagram
 Identify the following propositions
using the categorical symbols they
represent and afterwards use the Venn
diagram to illustrate the following:
 1. Many contemporary philosophers
are Existentialists.
 2. All criminals are bound to be
imprisoned.

17.  3. Many students are not studios.
 4. Practically all magicians are
circus attractions.
 5. No coward persons are brave.
 6. All apples are fruits.
 7. Some athletes are world-class
swimmers.

18.  8. All statisticians are
mathematicians.
 9. several martyrs are saints.
 10. All environmentalists are
nature lovers.