TOULMIN LOGIC
►
►
Credited to historian &
philosopher Stephen
Toulmin, Toulmin
logic is a generally
accepted standard for
the logical, objective
examination of claims
made by scientists.
Toulmin logic bolsters
the Scientific Method
and demands that the
individual asserting a
claim be honest and
objective.
4 factors in toulmin logic
►Claim
►Data
►Warrant
►Backing
► You
already know that to make an
argument, you need at least two
things: a thesis or claim and evidence or
data to support the claim.
► But, as we just discussed, facts (data)
don't speak for themselves.
► Say we have the following datum:
► Many people who have been hypnotized
recall alien abduction scenarios.
► And we want to use this datum to
support the following claim:
► Alien abduction is a real phenomenon.
► What else do we need? What’s missing?
► What's
missing is what we call the
warrant, the connection between data
and claim, the thing that speaks for the
facts.
► In this example, the warrant is:
► Hypnosis is a valid means of recovering
suppressed memories.
► The
WARRANT
connects claim
and data.
► an “inferential
leap” between
these two.
► performs a
"linking" function
by establishing a
mental connection
between the data
and the claim
► CLAIM:
► Aka
“thesis,” “your
point,” etc.
► DATA:
► Can
use any
number of
different types of
evidence; exactly
what evidence is
accepted depends
on rhetorical
situation.
► If
you present the datum “He really
loves kids” to support the claim,
“Bill is going to be a really good
teacher,” what is your warrant?
► If
you claim that “Debbie is a liar,”
and your evidence/data is,
“Debbie’s told us ten things about
the Johnson Contract and all ten
have turned out to be untrue,” the
warrant is __________________.
OK, so why is this important?
► Because
a lot of the time, the warrant is
►
1) not revealed, only assumed; and
►
2) not necessarily true. To determine
whether a warrant is true or not, we
examine the evidence for it. Toulmin
called this evidence BACKING.
► WARRANTS
can be very difficult to
detect, because they are often based on
very common patterns of reasoning or
very common values.
But Because They’re Hard to
Detect -► --
It’s especially important to find
them.
► Very often, when someone is trying
to put a fast one by you, they’re
doing it through the warrant. Or
when people think sloppily, they’re
using an invalid warrant.
► Very often, the best way to critique
an argument is through its
warrants.
Cornwell’s Portrait of a
Killer: Jack the Ripper
-- Case Closed
Cornwell’s central
claim is that Jack
the Ripper was
really Walter
Richard Sickert, a
relatively wellknown English
painter of the late
19th Century.
Claim: Sickert was Jack the
Ripper.
► DATUM:
One of the letters that
purported to be from Jack the Ripper
was written on the same brand of
stationery as a letter from Sickert.
► WARRANT: ___________________
Claim: Sickert was Jack the
Ripper.
► DATA:
Sickert had an operation as a
child that left him unable to have a
normal sex life. We know today that
many serial killers are impotent.
► WARRANT: ___________________
Claim: Sickert was Jack the
Ripper.
► DATA:
Sickert painted a picture in
1908 called "Jack the Ripper’s
Bedroom," described by an art historian
as being "very dark and
disturbing." Sickert often painted
scenes of violence against women.
► WARRANT:
___________________