Ignoratio Elenchi: The Red Herring Fallacy

Abstract

Ignoratio Elenchi: The Red Herring Fallacy

Full text

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article
IGNORATIO
ELENCHI:
The
Red
Herring
Fallacy
Dougias
N.
Walton
University
of
Winnipeg
It
is
a
longstanding
presumption
of
the
tradition
of
logic
that
several
major
infor-
mal
fallacies
essentially
involve
failure
of
topical
appropriatene~s
or
relevance.
The
~
baculum!
the
ad
~opulum,
and
th7
ad
m~ser~cord~am
each
~nvolve
an
emot~onal
appeal.!
But
there
need
be
nothing
wrong
with
appeals
to
emotion
as
such,
nor
need
an
appeal
to
emotion
even
involve
argument,
let
alone
fallacious
argument.
Indeed,
many
an
emotional
appeal
is
deceitful
as
a
complete
abandonment
of
argument
covered
up
by
the
distraction
of
a
naked
appeal
to
emotion.
~fuat
can
be
fallacious
in
emotional
appeals
however,
where
there
is
argument,
is
that
the
proposition
that
appeals
to
emotion
turns
out
to
be,
in
some
important
sense,
irrelevant
to
the
conclusion
to
be
argued
for.
Thus
if
an
advertiser
tries
to
communicate
the
idea
that
his
product
is
popular,
there
may
be
nothing
fallacious
in
that.
But
if
popularity
is
a
premiss
for
the
conclusion
that
his
product
is
a
good
buy,
or
technically
or
nutrition-
ally
sound,
an
ad
POtUlum
may
be
in
the
of-
fing.
Reason:
:popu
ar~ty
is
not
an
appro-
priate
or
relevant
basis
for
establishing
technical
performance
or
nutritional
ade-
quacy
of
a
product.
One
has
simply
strayed
off
topic
altogether.
The
ad
hominem
is
another
case
in
point.
PersonaT
characteristics
or
circumstantial
factors
may
often
fail
to
be
argumentatively
connected
in
any
serious
way
to
the
conclusion
at
issue.
Perhaps
it's
true
that
our
physi-
cian
who
cites
evidence
of
the
dangers
of
smoking
cannot
herself
give
up
the
habit.
Yet
to
dwell
on
this
interesting
circumstan-
tial
inconsistency
may
commit
an
irrelevant
appeal
by
masking
the
fact
that
the
evidence
cited
by
the
physician
is
reasonable
and
good
evidence,
not
to
be
overlooked.
2
Similarly,
ad
verecundiam
3
may
dwell
on
an
appeal
to
the
sayso
of
some
glamorous
"expert"
in
lieu
of
evaluating
serious
evidence
for
or
against
some
proposition.
The
term
ignoratio
elenchi
(misconception
of
refutation)~ften
used,
following
in
the
Aristotelian
tradition,
to
refer
to
fail-
ure
of
relevance
in
argument.
But
as
Hamblin
3
comments,
until
we
have
some
firm
idea
of
what
is
meant
by
"relevance"
in
this
context,
just
calling
failure
of
relevance
a
fallacy
is
not
any
help.S
And
indeed,
historically
the
ignoratio
elenchi
has
tended
to
become
a
rag-bag
category
to
cover
any
argument
where
the
author
is
uncertain
why
it
is
fallacious.
What
has
happened
is
that
the
ad
gorulum,
ad
hominem,
and
other
major
fallaCIes,
have
~
stayed
in
the
textbooks,
but
with
the
lame
~xplanation
that
they
are
somehow
failures
of
an
argument
to
be
relevant,
The
problem
is
that
until
we
know
what
Qrelevant"
means" we
have
no
clear
guidelines
for
showing
clearly
what
really
is
fallacious
about
these
argu~
ments
that
so
strongly
seem
to
go
wrong
by
being
off
topic,
Formal
logic
does
not
seem
to
be
any
help
in
resolving
the
problem.
It
is
well
known
that
classical
logic
has
theorems
like
p
:::>
(q
:>p)
and
-p::)
(p
::>q),
which
suggests
that
classical
logic
is
simply
neutral
on
the
issue
of
whether
p
and
q
are
in
any
way
topi-
cally
related
to
each
other.
The
classical
material
'If,
••
then'
or
0,
only
assures
us
that
p::> q
never
takes
us
from
a
true
p
to
a
false
q,
never
mind
whether
p
and
q
are
connected
in
any
way,
The
branch
or
formal
logic
called
relevance
logic
is
specifically
designed
to
deal
with
"fallacies
of
relevance"
like
the
two
clas-
sical
tautologies
above.
But
the
problem
with
it
is
that
although
it
offers
a
variety
of
formal
logics
based
on
the
idea
of
rele-
vance,
somehow--at
least
so
far--it
has
not
provided
us
with
a
clear
basic
idea
of
what
"relevance"
means
in
one
or
more
of
these
formal
logics.
We
need
a
concept
of
rele-
vance
that
can
be
applied
to
fallacies
like
the
ad
baculum
and
ad
verecundiam
so
that
we
can
see
spec~ficallY-how
these
arguments
are,
at
least
sometimes,
dramatic
failures
of
a
proposition
to
be
relevant
to
a
given
argu-
ment
or
conclusion.
"Relevant",
that
is,
in
a
sense
which
shows
us
why
such
arguments
can
correctly
be
said
to
be
fallacious.
The
prob-
lem
is
that
the
philosophical
task
of
showing
the
relevance
of
relevance
logics
to
the
major
fallacies
of
relevance
remains
unsolved,
or
perhaps
even
unaddressed.
It
is
by
no
means
clear
that
"relevance"
in
the
technical
sense
of
relevance
logic
is
the
same
concept
of
relevance
that
is
meant
when
we
say
that
the
ad
misericordiam
is
a
fallacy
of
relevance.
Part
of
the
problem,
as
we
will
see,
is
that
quite
a
variety
of
notions
of
the
connections
between
the
antecedent
and
consequent
of
a
conditional
proposition
could
be
involved.
"Relevance"
could
mean
all
kinds
of
things,
but
let
us
go
back
to
the
basic
idea
so
often
expressed
that
a
proposition
p
is
connected
to
(relevant
to,
related
to)
another
propo-
sition
q,
if
p
and
q
share
meaning
content.
Suppose
we
begin
with
the
idea
that
an
argument
or
discourse
is
about
a
set
of
topics,
T.
Of
course,
with
many
arguments,
the
set
of
topics
that
the
argument
can
com~
prise
is
not
firmly
agreed
on
by
the
partic~
ipants
at
the
outset.
But
to
work
towards
what
we
want
to
analyse,
let
us
adopt
the
model
of
an
argument,
after
Hamblin,
as
an
interchange
~etween
participants.
An
argu-
ment,
by
these
lights
is
then
a
sort
of
inter-
change
or
discourse
between
arguers,
a
back

and
forth
sequence
of
moves
and
countermoves.
For
a
given
discourse,
let
us
make
the
as~
sumption
that
the
participants
can
establish
a
set
of
topics
that
comprises
the
legitimate
subject
of
that
discourse.
Given
an
overall
set
of
topics
for
a
given
series
of
inter-
changes,
we
can
then
look
at
any
particular
argument
that
is
part
of
that
series,
and
evaluate
whether
or
not
it
is
"off
topic".
Following
a
suggestion
made
by
David
Lewis,
we
take
every
proposition
p,
q,
r,
•••
,
in
the
discourse
we
are
concerned
with,
and
assign
it
its
subject-matter,
called
£,
~,
r,
• • • ,
which
is
in
each
case
a
subset
or
T76
Then
we
can
say
that
p
is
related
to
q
if
there
is
subject-matter
overlap
between
£
and
~.
For
example
if
'Bananas
are
yellow'
con-
tains
the
subject-matters
'bananas'
and
'yel-
low',
and
'Bananas
are
nutritious'
contains
the
subject-matters
'bananas'
and
'nutri-
tious',
then
the
two
propositions
are
related.
They
both
contain
the
topic
'bananas'
in
their
subject-matters.
This
,is
a
clear
and
simple
idea
of
"relevance",
or
relatedness
as
we
prefer
to
call
it,
that
provides
a
begin-
ning
point
for
exploring
fallacies
like
those
we
have
mentioned.
Clearly
'p
is
related
to
q'
in
the
sense
of
overlapping
subject-matters
is
a
relation
that
is
reflexive
and
symmetrical,
but
not
transitive.
The
following
example
will
show
why
transitivity
fails.
'Bananas
are
yellow'
is
related
to
'There
are
two
bananas
on
my
desk'.
And
the
second
proposition
is
related
to
'2+2=4'.
But
'Bananas
are
yellow'
is
not
related
to
'2+2=4'.
Here
at
any
rate
is
one
clear
conception
of
relatedness
of
propositions--that
of
subject-
matter
overlap7_-that
offers
a
place
to
begin
in
analyzing
fallacies
of
relevance.
A
typical
example
of
irrelevance
in
argu-
ment
is
given
by
Johnson
and
Blair
(1977,
p.
54),
where
then-Senator
Paul
Martin
took
exception
to
the
slur
contained
in
Arthur
Hailey's
Wheels
that
Windsor
is
as
grimy
and
ugly
as
Detro~E.
Martin
responded:
When I
read
this
I
was
incensed
• • •
Those
of
us
who
live
there
know
that
INindsor]
is
not
a
grimy
city.
It
is
a
city
that
has
one
of
the
best
flower
parks
in
Canada.
It
is
a
city
of
fine
schools,
hard-working
and
tolerant
people.
In
critically
analyzing
this
argument,
John~
son
and
Blair
point
out
that
Martin's
initial
point
about
the
flower
park
does
tell
against
Hailey's
appraisal.
But
instead
of
continuing
to
build
his
case
for
the
beauty
of
Windsor,
the
Senator
changed
the
subject,
by
effecting
a
quick
transition
to-Dther
topics:
the
hard-
working
and
tolerant
characteristics
of
the
people
of
Windsor.
This
shift
is
a
red
her-
ring
or
ignoratio
elenchi
move
in
the
argu-
ment,
as
Johnson
and
Bla~r
point
out.
The
thrust
of
the
argument
runs
something
like
this,
if
we
break
it
down
into
distinct
premisses.
Premiss
1:
Windsor
has
one
of
the
best
flower
parks
in
Canada.
Premiss
2:
Windsor
has
fine
schools.
4
Premiss
3:
Nindsor
has
hard-working,
toler-
ant
citizens.
Conclusion:
Windsor
is
not
a
grimy
city.
Now
the
question
is:
how
could
what
is
fal-
lacious
about
this
argument
be
shown
to
be
an
incorrect
argument
in
a
relatedness
model-
ling?
The
evidently
insuperable
initial
problem
is
this:
the
fact
is
t~t
there
is
subject-matter
overlap
between
every
premiss
and
the
conclusion
of
the
argument.
There-
fore,
if
ignoratio
elenchi
is
failure
of
subject-matter
overlap,
then
the
above
argu-
ment
is
definitely
not
an
ignoratio
elenchi
at
all!
What
I
think
this
shows
is
that
subject-
matter
overlap
between
premisses
and
conclu-
sion
does
not
constitute
a
sufficient
condi-
tion
of
correct
argument.
Perhaps
another
illustration
will
make
this
point
more
clear-
ly.
The
thirteenth
century
logician
l'lilliam
of
Sherwood
cites
the
two
arguments
oelow
as
incorrect.
They
are
cited
as
instances
of
Ignorance
Regarding
Refutation
(Ignoratio
Elenchij--see
the
translation
of
Kretzmann
(1966,
p.
156).
(1)
Socrates
is
naturally
pious,
but
he
is
not
absolutely
pious;
there-
fore
he
is
both
pious
and
not
pious.
(2)
Socrates
is
running
at
time
a
(currit
in
al
and
he
is
not·running
at
time
bi
thererore
he
is
ooth
running
and
not
running.
Now
notice
that
in
both
these
arguments
there
is
subject-
matter
overlap
between
premisses
and
conclu-
sion,
yet
botA
arguments
are
clearly
incor-
rect.
Indeed,
both
are
sophismatical
or
fallacious
arguments
from
premisses
that
are
possibly
true
to
a
conclusion
that
can't
be
true.
So
subject-matter
overlap
is
not
enough
to
rule
out
fallaciousness.
To
be
a
correct
argument
meeting
reasonable
standards
that
will
avoid
i~noratio
elenchi,
not
only
must
there
be
subJect-matter
overlap
but
also
the
argument
must
not
allmoT
us
to
go
from
true
premisses
to
a
false
conclusion.
Hence
the
relatedness
conditional,
p
~q,
must
incor-
porate
both
requirements
that
(1)
it
is
not
the
case
that
p
is
true
and
q
is
false,
and
(2)
p
is
related
to
q.
In
short,
the
reason
why
Senator
Hartin's
argument
fails
is
not
failure
of
subject-
matter
overlap,
but
by
virtue
of
the
fact
that
the
second
two
premisses
simply
fail
to
imply
the
conclusion,
either
deductively
or
inductively.
It
is
neither
impossible
nor
improbable
that
a
grimy
city
might
have
hard-
working
and
tolerant
citizens.
Still,
one
might
persist,
isn't
the
red
herring
really
explained
by
the
evident
pre-
sumption
that
'has
hard-working
tolerant
citizens'
as
a
property
of
some
city
x,
fails
to
have
subject-matter
overlap
with
'is
not
a
grimy
city'
for
any
x.
The
suggestion
is
that
the
following
argument
fails
by
reason
of
lack
of
subject-matter
overlap,
where
x
is
any
city.
Premiss
1:
For
all
x,
x
has
fine
schools.
Premiss
2:
For
all
x,
has
hard-working,
tolerant
citizens.
Conclusion:
For
all
x,
x
is
not
a
grimy
city.
And
to
be
sure,
this
argument
does
fail
to
have
significant
subject-matter
overlap,
and
is
a
bad
argument.
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ity.
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and
So
perhaps
there
is
a
second
explanation
of
what
is
fallacious
about
Senator
~~rtin's
argument.
It
is,
by
these
lights,
really
a
true
red
herring
after
all
and
not
merely
a
failure
of
implication
not
specifically
due
to
subject-matter
disjointedness.
Still,
even
if
this
second
analysis
is
acceptable,
our
general
point
remains
that
subject-matter
connectedness
by
itself
is
not
enough
to
as-
sure
correctness
of
an
argument,
as
the
ex-
amples
from
William
of
Sherwood
show,
For
we
cannot
analogously
reconstruct
the
liilliam.s
arguments
as
failures
of
subject
matter
over
...
lap.
For
example
the
reconstruction
of
(ll
as
follows
remains
incorrect:
for
some
indi
...
vidual
x,
x
is
naturally
pious
but
x
is
not
absolutely
pious;
therefore
x
is
both
pious
and
not
pious.
This
argument
is
incorrect,
but
it
still
has
subject-matter
overlap
be
...
tween
premisses
and
conclusion.
Therefore
generally
we
must
conclude
that
ignorance
of
refutation
involves
more
than
just
failure
of
subject-matter
overlap.
TOpics
are
involved
essentially,
but
they
are
not
the
whole
story
about
ignoratio
elenchi.
As
can
be
seen
by
the
examples
cited
above
from
William
of
Sherwood,
the
traditional
Aristotelian
fallacy
of
ignorance
of
refuta-
tion
was
not
restricted
merely
to
instances
of
failure
of
subject-matter
overlap.
In-
deed,
the
Aristotelian
tradition
of
the
"topics",
so
influential
in
medieval
logic,
distinguished
numerous
different
kinds
of
connections
or
"topics"
that
could
relate
the
premisses
and
conclusion
of
a
correct
argu~
ment.
Boethius
followed
Cicero's
conception
of
a
topic
as
sedes
argumenti
(a
seat
of
argu-
ment),
and
described
it
as
"that
from
which
a
fitting
argument
may
be
drawn
for
a
proposed
question"
(De
Differentiis
Topicis).
For
these
earlier
authorities,
a
topic
functions
primarily
as
a way
of
finding
new
arguments,
but
for
later
writers
like
Abelard
and
Ockham
the
topic
became
the
inferential
basis
of
a
conditional
proposition.
Abelard
claims
that
the
topics
show
the
in-
ferential
force
(vis
inferentiae)
of
all
con-
ditionals.
According
to
Bird
(1960)
Abelard
uses
the
topic
as
an
"inference-warrant"
that
can
accommodate
formal
as
well
as
non-formal
inferences.
An
example
of
Abelard's
is
that
'If
it
is
man,
it
is
animal'
is
a
correct
(good
and
necessary)
inference
whereas
'If
it
is
stone,
it
is
animal'
is
not,
because
the
second
lacks
the
relation
of
the
Topical
Difference
of
Species.
However,
it
is
clear
that
genus-species
was
not
the
only
topical
relation
recognized
by
the
medievals,
and
in
fact
the
diversity
of
the
dialectical
topics
subdivided
the
kinds
of
correct
conditionals
they
recognized
into
many
classifications.
For
example
we
find
in
Peter
of
Spain
an
enumeration
of
some
twenty-
one
topics
including
part-whole
relations,
attributions
of
place
and
time,
causation,
similarity,
authority,
adverbial
modification.
and
so
forth.
~'Jhat
is
corranon
to
them
is
that
a
topic
is
always
a
relation
that
warrants
an
inference.
This
tradition
of
the
topics
suggests
that
the
application
of
formal
theories
of
the
conditional
to
the
wide'
varieties
of
failure
of
correct
inference
that
are
involved
in
many
informal
fallacies
and
practical
argu~
5
ments
is
no
simple
matter.
It
appears
to
involve
many
different
kinds
of
relations
that
link
the
antecedent
to
the
consequent
in
conditionals,
Subject-matter
overlap
is
one
such
relation
that
helps
to
clarify
one
sense
of
"failure
of
relevance"
central
to
under-
standing
the
modern
conceptions
of
the
ad
~pUlurn,
ad
hominem
and
related
fallacies.
crearly
however,
other
kinds
of
relatedness
relations
are
involved
as
well,
if
the
many
different
varieties
of
conditional
used
in
practical
arguments
are
to
be
studied.
Let
us
turn
to
seeing
how a
general
theory
of
relatedness
could
be
formulated
to
accom-
modate
the
above
requirements
and
still
allo,,,
for
a
good
deal
of
flexibility
in
application
to
specific
arguments.
\'le
will
see
that
it
can
be
done
by
modifying
the
usual
proposi-
tional
calculus
and
requiring
the
relatedness
of
antecedent
and
consequent
in
order
for
a
conditional
to
obtain.
Could
such
a
formal
approach
be
useful?
Uany
of
those
who
are
drawn
to
informal
logic
see
it
as
a
subject
that
shows
pedagog-
ical
promise
in
teaching
students
how
to
han-
dle
the
practicalities
of
evaluation
of
argu-
mentation
in
pragmatic
situations
like
the
consumer
marketplace.
Because
they
see
it
as
a
practical
discipline
they
are
skeptical
that
formal
logic
can
be
meaningfully
appli-
cable
to
realistic
argumentation.
After
all,
doesn't
formal
logic
rest
on
a
propositional
calculus
that
certifies
as
valid
argument
forms
schemata
like
...,p::>
(p
::>
q)
?
How
could
a
logic
that
allows
conditionals
to
obtain
between
ostensibly
unrelated
proposition
be
applicab1
7
to
fallacies
like
the
ad
populum
or
ad
hom1nem?
Yet
on
the
other
hand,
if
formal
guidelines
on
what
constitutes
correct
versus
incorrect
forms
of
argument
are
not
ava11able,
how
coul&
practical
logic
of
the
informal
sort
ever
offer
clear
and
precise
guidelines
for
eval-
uating
arguments?
perhaps
the
dilerrana
can
be
ameliorated
by
clarifying
more
precisely
what
is
meant
by
"formal
logic"
in
this
context.
True,
clas-
sical
PC
is
not
a
model
of
argument
that
suits
the
fallacies
of
subject-matter
related-
ness,
but
perhaps
other
formal
approaches
that
deviate
from
classical
logic
in
order
to
capture
the
relevant
sense
of
proposi-
tional
connectedness
could
be
more
useful.
One
formal
approach
that
shows
great
promise
in
studying
fallacies
associated
with
failure
of
subject-matter
overlap
is
the
relatedness
logic
of
Epstein
(1979).
In
relatedness
logic,
the
conditional
p ~ q
is
defined
as
incorporating
the
classical
requirement
that
it
not
be
the
case
that
p
is
true
and
q
false
with
the
additional
requireMent
that
p
be
related
to
q.
R(p,q)
is
read
as
'p
is
related
to
q',
a
relation
that
is
ref1
7
xive
and
non-transitive.
It
may
be
syrranetr1cal
or
not,
as
you
wish,
but
if
relatedness
is
interpreted
as
meaning
'subject~matter
over-
lap
of
p
with
q'
t~en
clearly
it
is
also
a
symmetrical
relation.
Negation
is
defined
in
the
classical
way.
Conjunction
and
disjunc-
tion
may
be
defined
either
as
classical
or
as
requiring
relatedness,
as
you
wish.
However,
it
is
proposed
in
Walton
(1979)
that
for
purposes
of
subject-matter
relatedness,
it
is
natural
to
think
of
disjunction
as
requiring

I
II
i
~
,
~
' .
•
II'!
.1
relatedness,
but
to
think
of
conjunction
as
classical,
i.e.
not
requiring
relatedness.
The
final
building
block
that
yields
a
formal
logic
of
relatedness
is
to
show how
the
com-
plex
formulas
are
related
to
the
simple
for-
mulas.
The
key
ruling
is
this:
p
is
related
to
q
~
r
if,
and
only
if,
p
is
related
to
q
or
p
is
related
to
r.
This
ruling
seems
reasonable
for
subject-matter
relatedness
because
it
is
natural
to
say
that
'Socrates
is
snub-nosed'
is
related
to
'If
Socrates
sprints
then
some man
is
running'
because
the
simple
proposition
is
related
to
one
of
the
propositions
in
the
conditional,
namely
the
antecedent.
Given
the
requirements
set
out
above,
what
forms
of
inferences
come
out
valid
or
invalid?
The
usual
truth-table
decision
procedure
en-
ables
us
to
determine
tautologies.
Consider
modus
ponens.
p q
R(p,q)
p-q
(p-q)-q
p
-[
(p-q)
-q]
T T : T T T T
T T F F T T
T F T F T T
T F F F T T
F T T T T T
F T F F T T
F F T T F T
F F F F T T
As
you
can
see,
the
truth-tables
are
similar
to
classical
logic
except
that
we
must
take
relatedness
into
account,
in
addition
to
the
truth-values
of
~~e
propositions.
As
an
example
of
a
classical
tautology
that
fails
in
relatedness
logic,
consider
[(p
1\
q)
...
r]
...
[Cp
....
r)
v (q
...
r)].
This
schema
can
fail
as
follows.
Let
q
be
true
and
r
false,
then
the
q
~
r
in
the
consequent
is
false.
Let
p
be
unrelated
to
r,
then
p ... r
in
the
consequent
is
false.
Hence,
on
this
interpretation
the
consequent
is
false.
But
assume
p
is
false.
Then p 1\ q
in
the
antecedent
is
false,
hence
(p 1\ q)
...
r
must
be
true,
assuming
that
q
is
related
to
r,
an
assumption
that
is
consistent
with
the
as-
signments
given
to
the
consequent.
In
short,
there
is
a
consistent
assignment
of
truth-
values
and
relatedness
relations
that
makes
the
antecedent
of
the
schema
in
question
come
out
true
and
the
consequent
come
out
false.
Hence
the
schema
fails
to
be
a
tautology.
In
general,
truth-tables
always
enable
us
to
tell
whether
an
argument
is
correct
or
not
in
re-
latedness
logic.
To
see
how
rejection
of
the
schema
above
applies
to
practical
arguments,
consider
a
syllogism
like
this:
All
men
are
mortal
(p),
Socrates
is
a man
(q),
therefore
Socrates
is
mortal
(r).
It
is
true
that
(p
A q)
~
r
applies,
but
it
is
false
that
(p
~
r)
V
(q
~
r)
applies.
Hence
it
is
"paradoxical"
indeed
that
[(p
A q) :>
r]
:> [ (p
::>
r)
V
(q'~
r)]
is
a
tautology
in
classical
PC.
More
usual
"paradoxes"
cited
are
_p
':)
(p
::>
q)
and
q:>
(p
:>q),
but
these
too
fail
to
be
relatedness
tautologies.
In
short,
related-
6
ness
logic
turns
out
to
be
a
subsystem
of
classical
PC.
All
relatedness
tautologies
are
classical
tautologies,
but
there
are
some
classical
tautologies
that
fail
in
re-
latedness
logic.
We
can
summarize
our
findings
as
follows.
Many
traditional
major
informal
fallacies
can
be
and
often
are
categorized
as
involving
a
failure
of'propositions
to
be
related
to
each
other.
Particularly,
what
seems
to
be
upper-
most
in
mind
is
failure
of
subject-matter
overlap.
But
the
traditional
study
of
the
logic
of
the
topics
suggests
that
there
can
be
many
different
kinds
of
relatedness
in-
volved
in
studying
sophismata
that
reflect
fallacies
important
to
practical
reasoning
by
conditionals.
However,
we
can
focus
on
subject-matter
overlap
as
one
particularly
central
and
clearly
definable
species
of
relatedness,
If
we
are
to
construct
a
general
theory
of
conditionals
based
on
relatedness
that
is
useful
in
studying
the
underlying
fallacy
of
ifinoratio
elenchi
that
is
common
to
fallacies
t
at
go
wrong
by
failure
of
relatedness,
we
must
be
clear
that
subject-matter
connected-
ness
is
not
by
itself
sufficient
to
assure
correctness
of
an
argument.
In
addition,
we
must
requir~
that
a
correct
argument
does
not
go
from
true
premisses
to
a
false
conclusion.
Ianoratio
elenchi,
whether
it
be
character-
ize
as
failure
of
subject-matter
overlap
in
conditionals,
or
as
failure
of
any
kind
of
relatedness,
is
a
general
kind
of
fallacy
that
helps
to
explain,
at
least
partly,
what
has
often
thought
to
be
fallaciOUS
about
arguments
like
the
ad
POtUlum
or
ad
hominem.
But
it
is
only
part-of
t e
story
of
these
other
fallacies,
and
specific
studies
of
these
various
individual
fallacies
help
to
bring
out
other
important
aspects
of
them.
Notes
lSee
Walton
(1980).
2see
Woods
and
Walton
(19771.
3
see
Woods
and
Walton
(19741.
4
But
sometimes
also
translated
as
Uignorance
of
refutation
If
,
SActually,
as
Hamblin
indicates,
and
as
will
be
pointed
out
below,
the
Aristotelian
con~
ception
of
ignoratio
elenchi
may
be
somewhat
different
from
inferences
that
many
modern
writers
might
tend
to
classify
as
fallacies
of
relevance.
6
see
also
Epstein
(1979,
p.
156
f.).
7Another
notion
of
related
is
that
of
temporal
adjacency
in
an
act-sequence.
R
(p,q)
in
this
context
has
this
meaning:
what
makes
p
true
can
affect
what
makes
q
true.
80ther
classical
tautologies
that
obtain
in
relatedness
logic
are
modus
tollens,
contra~
position,
disjunctive
syllogism,
and
reductio
ad
absurdum,
i.e.,
(p _
q)
-+
[(p
-+
-q)
-
-p]-:-
9Some
other
principles
that
fail
are
ex-
portation,
hypothetical
syllogism
and
addi~

s
e-
s.
can
a
each
per-
e
an
t
g
by
Y
of
of
.cies
we
.ed-
'e
we
:
not
:ion.
·ter-
i
in
if
rhat
~.
.0
I.
trance
:
will
In
...
rhat
~n
.es
:patio-
:(p,q)
lakes
. n
in
:ra
...
)~
K-
:ii~ion,
i.e.
p
~
(p
V
q).
It
is
clear
that
related
...
ness
logic
is
different
from
relevance
logic
--see
l"lalton
(19.79).
References
Otto
Bird,
"The
Formalizing
of
the
Topics
in
Mediaeval
Logic,"
Notre
Dame
Journal
of
Formal
Logic,
1,
1~38
.. 149. -
Richard
L.
Epstein.
"Relatedness
and
Implica-
tion,"
Philosophical
Studies,
36,
1979,
137-173.
R.
H.
Johnson
and
J.
A.
Blair,
Logical
Self~
Defense,
Toronto
and
New
York,
McGraw=-
Hill
Ryerson,
1977.
Norman
Kretzmann
..
trans.
and
ed.,
William
of
Sherwood's
Introduction
to
L?g~c,
Hinneapolis,
Un~vers~ty
of
M~nnesota
Press,
1966.
Douglas
N.
Walton,
"Philosophical
Basis
of
Relatedness
Logic,",Philosophical
Studies,
36,
1979.
115-136.'
Douglas
N.
Walton,
"Why
is
the
Ad
POJilulum
a
Fallacy?"
Philosophy
~
Rfietor~c,
to
appear,
1980.
John Woods
and Douglas
l"lalton,
"ARtiumentum
ad
Verecundiarn,
"
Philosophy
and
etoric,
r,
1974,
135-153.
--
John
vloods
and
Douglas
Walton,
"Ad Hominem,"
~
Philoso~hical
~,
8,
~77,
1-20.
responses
Mare
on
Deductive
and
Inductive
Arguments
Trudy
Govier
Trent
UniverSity
The
existence
of
confusing
material
in
textbooks
has
not
been
enough
to
convince
Samuel
Fohr
that
the
distinction
between
in-
ductive
and
deductive
arguments
should
be
re-
linquished.
CSee"
The
Deducti
ve-
Inducti
ve
Distinction",
Informal
'L09tc
Newsletter,
ii.2.l
Fohr
proposes,
fol
owing
a
definition
in
Olson's
Meaning
~
Argument,
that
the
distinction
between
deduct~ve
and
inductive
7
arguments
be
established
on
the
grounds
of
the
intentions
of
the
person
putting
forward
the
argument.
Arguments,
he
says,
are
people's
arguments;
they
are
put
forward
in
order
to
convince
other
people.
People
may
intend
either
that
their
arguments
provide
conclusive
reasons
for
what
they
are
trying
to
demonstrate,
or
that
they
provide
less
than
conclusive
reasons.
In
the
first
case,
an
arguer's
intentions
establish
his
argument
as
deductive.
In
the
second
case,
they
make
it
inductive.
A
desirable
consequence
of
this
approach
is
that
it
provides
for
both
good
and
bad
arguments
in
each
category.
Most
of
the
time,
Fohr
thinks,
we
are
able
to
tell
what
an
arguer's
intentions
are,
or
were.
If
we
cannot,
we
must
judge
the
argument
"both
ways".
This
proposal
does
not
strike
me
as
very
satisfactory.
I
am
surprised
that
Fohr,
who
says
that
he
cannot
accept
"purportedly
valid"
as
a
definition
of
'deductive
argument',
can
rest
content
with
an
appeal
to
intention
here.
I
have
the
following
difficulties
with
his
proposal:
1.
Either
there
will
be
evidence
for
the
arguer's
intentions
regarding
conclusiveness
in
the
wording
of
his
argument,
or
there
will
not.
In
the
first
case,
intentions
and
"purported
validity"
or
"involving
a
claim
to
validity"
(Copi)
will
amount
to
much
the
same
thing.
There
are
numerous
examples,
as
Fohr
admits,
where
wording
is
not
helpful.
After
all,
conclusiveness
in
the
sense
of
logical
entailment
is
a
philosopher's
concept,
and
even
such
English
words
as
"must",
"there-
fore",
and
"shows
conclusively"
will
not
provide
a
reliable
basis
for
inferring
that
the
arguer
is
claiming
conclusiveness
in
the
sense
that
the
premises
are
supposed
to
10*ica11
Y
entia1
the
conclusion.
If,
on
the
ot
er
hand,
we
seek
to
avoid
these
difficul-
ties
with
wording--making
the
author's
safso
and
that
alone
the
criterion
for
determ~n~ng
his
intention--we
will
find
ourselves
unable
to
apply
the
distinction
to
many
cases
where
authors
are
dead
or
absent.
This
is
absurd
if
the
inductiye/deductive
distinction
is
supposed
to
be
a
fundamental
tool
in
the
assessment
of
argument.
We
can,
of
course,
look
at
the
indeterminate
arguments
"both
ways",
as
Fohr
suggests;
but
the
more
often
we
do
this,
the
more
often
we
are
bound
to
wonder
why
all
of
logic
should
have
been
erected
around
this
fuzzy
distinction
in
the
first
place.
2.
If
we
really
take
Fohr
seriously
on
the
over-riding
importance
of
intention,
then
we
will
have
to
accept
the
peculiar
consequence
that
there
are
inductive
arguments
which
are
deductively
valid,
and
deductive
arguments
which
are
inductively
strong.
For
instance,
suppose
someone
argues:
1.
Either
L€vesque
will
be
defeated
at
the
next
election,
or
he
will
win
and
call
another
referendum
.
2.
Since
Quebecers
are
fond
of
Levesque,
he
will
not
be
defeated
at
the
next
election.
3.
Thus,
there
will
in
all
likelihood
be
another
referendum.
This
argument
is
deductively
valid,
but
the
conclusion
contains
the
tentative
expression
"in
all
likelihood".
If
the
arguer
is
a