THE NATURE OF
PERSONS
PHYSICALISM AND
DUALISM
(“WHAT AM I?)

ORDINARY INDIVIDUAL THINGS
(TABLES, CHAIRS, CABBAGES,….)
ORDINARY INDIVIDUAL THINGS ARE MADE UP
OF PHYSICAL PARTS. A PHYSICAL PART OF
SOMETHING IS AN INDIVIDUAL THING OF THE
SORT STUDIED BY PHYSICS.
AT PRESENT (ACCORDING TO VAN INWAGEN)
THE MOST BASIC SORTS OF PHYSICAL THINGS
ARE THOUGHT TO BE QUARKS AND
ELECTRONS (AND CERTAIN OTHER PARTICLES).

DEFINITION OF PHYSICAL THING
A PHYSICAL THING IS A THING
COMPOSED ENTIRELY OF THE
SORTS OF INDIVIDUAL THINGS
INVESTIGATED BY PHYSICS. (OF
COURSE PHYSICS MAY DECIDE
THAT THERE ARE EVEN MORE
FUNDAMENTAL INDIVIDUAL
THINGS.)

WHAT AM I?
WE ARE MORE FAMILIAR WITH OURSELVES
THAN WITH ANYTHING ELSE THAT THERE IS.
BUT WHAT KIND OF THING ARE YOU?
(1) I AM A PHYSICAL THING: A LIVE HUMAN
BODY. (PHYSICALIST ANSWER)
(2) I AM NOT A PHYSICAL THING. I AM AN
ENTITY THAT HAS A BODY (AT PRESENT). I
AM A NON-PHYSICAL THING: A MIND, A
SOUL, A SELF, OR A “PURE EGO.” (DUALIST
ANSWER)

ARE YOU IDENTICAL WITH YOUR
BODY?
PHYSICALISM: A PERSON IS A HUMAN
ORGANISM, A PHYSICAL THING.
STRONG PHYSICALISM: EVERY INDIVIDUAL
THING IS A PHYSICAL THING.
PROPERTY PHYSICALISM: EVERY PROPERTY OF
ANYTHING IS A PHYSICAL PROPERTY
(A PHYSICAL PROPERTY IS ONE THAT CAN BE
POSSESSED BY PHYSICAL THINGS AND ONLY
PHYSICAL THINGS)

IS MIND SWAPPING POSSIBLE?
VARIOUS STORIES IN FICTION HAVE PLOTS
ACCORDING TO WHICH TWO PEOPLE CAN
EXCHANGE BODIES – THE MIND ASSOCIATED
WITH ONE BODY BECOMES ASSOCIATED WITH
ANOTHER, AND VICE-VERSA.
WHICH PERSON WOULD BE WHICH? IS SUCH A
THING REALLY EVEN POSSIBLE? IF A PERSON IS A
BODY, HOW CAN IT BE A DIFFERENT BODY? (ALSO
THERE ARE STORIES WHEREIN TWO MINDS
OCCUPY ONE BODY).

DUALISM
DUALISM IS THE THESIS THAT PERSONS ARE
NON-PHYSICAL THINGS (WE IGNORE
THEORIES ACCORDING TO WHICH PERSONS
ARE “AMALGAMS”: COMPOSED OF PHYSICAL
AND NON-PHYSICAL PARTS).
DUALISTS USUALLY MAINTAIN INTERACTIONISM:
THERE IS CAUSAL INTERACTION IN BOTH
DIRECTIONS BETWEEN A PERSON AND
HIS/HER BODY.

INTERACTIONISM HAS PROBLEMS
MANY PHILOSOPHERS HAVE HAD DIFFICULTY
SEEING HOW IT IS POSSIBLE FOR A NON-
PHYSICAL THING TO CAUSALLY INTERACT
WITH A PHYSICAL THING (HOW CAN I, IF I AM
A NON-PHYSICAL THING, CAUSE PHYSICAL
CHANGES IN MY BODY?)

RENE DESCARTES
ON INTERACTION

THE SOUL CAN ONLY INTERACT WITH
THE BRAIN VIA THE PINEAL GLAND

ARGUMENTS FOR DUALISM
“DESCARTES’ ARGUMENT”
I CAN CONCEIVE OF THERE BEING
NO PHYSICAL BODIES.
I CANNOT CONCEIVE THAT I DO
NOT EXIST.
THEREFORE:
I AM NOT A PHYSICAL BODY.

A LOGICAL PRINCIPLE
THE INDISCERNIBILITY OF IDENTICALS
(OR: THE DISTINCTNESS OF
DISCERNIBLES)
(DD) FOR ANY PROPERTY F AND ANY
THINGS X AND Y, IF X HAS F AND Y
DOES NOT, THEN X IS NOT IDENTICAL
WITH Y.

THIS PRINCIPLE DD SEEMS
UNIMPEACHABLE
IF X AND Y ARE THE VERY SAME THING (NOT
JUST SIMILAR OR EXACTLY ALIKE), THEN
ANYTHING THAT IS TRUE OF X IS TRUE OF Y
(THAT IS, X).
IN LOGICAL SYSTEMS IT USUALLY IS CALLED “THE
SUBSITUTIVITY OF IDENTICALS.”

NEVERTHELESS, THERE SEEMS TO BE
SOMETHING WRONG WITH THE
ARGUMENT
• COMPARE:
• (1) I CAN CONCEIVE OF BATMAN NOT
EXISTING AND AT THE SAME TIME BRUCE
WAYNE EXISTING.
• (2) I CANNOT CONCEIVE OF BRUCE WAYNE
EXISTING AND AT THE SAME TIME BRUCE
WAYNE NOT EXISTING.

THEREFORE:
( 3) SO BATMAN HAS A PROPERTY THAT
BRUCE WAYNE DOES NOT.
THEREFORE (BY DD)
(4) BATMAN IS NOT BRUCE WAYNE.
???!!!

VAN INWAGEN’S DIAGNOSIS
ACCORDING TO VAN INWAGEN,
THE PROBLEM IS THAT THE
PHRASE”
“…CAN BE CONCEIVED BY ME NOT
TO EXIST”
DOES NOT EXPRESS (DENOTE,
DESIGNATE) A PROPERTY.

A TEST FOR EXPRESSING A PROPERTY
CONSIDER A SENTENCE CONTAINING A PROPER
NAME (OR OTHER DESIGNATOR OF AN
INDIVIDUAL) AND REPLACE THE NAME BY THE
VARIABLE ‘X’.
“OBAMA IS PRESIDENT”
“X IS PRESIDENT”
“ANDERSON IS A PHILOSOPHER”
“X IS A PHILOSOPHER”

CALL THE RESULTING EXPRESSION A
“LOGICAL PREDICATE”
THE TEST: A LOGICAL PREDICATE EXPRESSES
(DENOTES, SIGNIFIES, CORRESPONDS TO) A
PROPERTY ONLY IF THE RESULTS OF
REPLACING ‘X’ BY TWO DIFFERENT
DESIGNATIONS OF THE SAME INDIVIDUAL ARE
BOTH TRUE OR BOTH FALSE.
TRY:
“COMMISIONER GORDON KNOWS THAT X IS
BATMAN.”

THE LOGICAL PREDICATE IN
DESCARTES’ ARGUMENT
“X CAN BE CONCEIVED BY ME NOT TO EXIST”
CONSIDER THE TWO DESIGNATORS:
“THE INSTRUCTOR OF PHIL 100E (S 2014)”
“I”
BOTH OF THESE DESIGNATE ME. BUT THE
LOGICAL PREDICATE FAILS THE TEST. (WHY? A
VERY INTERESTING QUESTION. CF.
PHILOSOPHY OF LANGUAGE).

A DIFFERENT DIAGNOSIS
THE ARGUMENT DEPENDS ON TAKING
“CONCEIVE” IN A PARTICULAR WAY. IN ONE
WAY OF TAKING IT, THE LOGICAL PREDICATE
MIGHT BE SEEN AS PASSING THE TEST. TAKEN
THAT WAY, THOUGH, IT IS DOUBTFUL THAT I
CAN REALLY CONCEIVE OF THE INSTRUCTOR
OF THIS COURSE AS NOT EXISTING.

A LEIBNIZIAN ARGUMENT AGAINST
PHYSICALISM