The Art of Argument:
Exploring Toulmin Logic
By Patrick, Daniel and Rodney
Stephen Toulmin
• British philosopher, author, and educator
• Devoted his works to the analysis of moral
reasoning
• Believed absolutism has limited practical value
• Introduced practical argument method
New System of Logic
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Based on justification rather than inference
More literal rather than theoretical
New argument could now stand up to criticism
Published in his book “The Uses of
Argumentation”
Definitions
Data: information that is gathered through
observation or experimentation
Warrant: inferences or assumed beliefs that support
the claim, can be based upon logos, pathos, ethos, or
shared values
Claim: the statement that one is asserting
Data
Claim
Warrant
Structure of Logic
• Using data, supported by a warrant, to form a claim.
• Warrant supports data which supports claim.
• Backing, qualifiers and rebuttals can further support
the claim
• Very literal and scientific approach
Data
Claim
Warrant
Data
Simple Example
Claim
Warrant
• Data: My pen is not writing on the paper
• Claim: My pen has run out of ink
• Warrant: Pens without ink do not write
One Step Further
• Backing: a credible source or citation, backing
up the warrant
• Qualifier: Indicates speaker’s degree of
certainty of the claim, often uses words such
as certainly, absolutely, maybe, etc.
• Rebuttal: argument opposing the opposition,
can be in the same setup (i.e. data, claim,
warrant),
Full Structure of Toulmin Logic
Qualifier
Claim
Data
Warrant
Rebuttal
Backing
Simple Example Expanded
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Data: My pen is not writing on the paper
Claim: My pen has run out of ink
Warrant: Pens without ink do not write
Backing: Bic came out with a study proving that
pens with less than 5% of the original supply of
ink cannot write properly
• Qualifier: I am completely sure this pen ran out
of ink
• Rebuttal: There are other problems that can lead
to the malfunction of pens, such as a broken tip
Advantages to using
Toulmin Logic
• Presents argument structure that facilitates
support and validity for said argument.
• Always room for doubt in an argument, leaving
room for reasons yet undiscovered and rebuttal
• Allows for logic to be updated as new discoveries
are made
• Arguments can be presented and debated as long
as you have some data to back up your claim
• Presents arguments literally rather than
theoretically (dichotomy)
Disadvantages to using
Toulmin Logic
• Does not allow for absolutes
• Requires an extensive support system if the
claim is to be validated
• Can always be disputed as there is always a
limited degree of validity
Uses in School
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Science Labs
Socratic Seminars
Persuasive Essays
Debates
Uses in the Real World
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Lawyers
Scientists
Statistics
Will
Politicians
Literary Analysts
Everyday life
Real Life Example
Each year, a World Championship Pumpkin Weights
Competition is held to determine the largest pumpkin
of the year. Here are the data for years 1979 to 2007
Year Weight (lb) Year Weight (lb) Year Weight (lb)
1979
438.5 1989
755 1999
1131
1980
459 1990
816.5 2000
1140
1981
493.5 1991
780.5 2001
1262
1982
445 1992
827 2002
1337.6
1983
481 1993
884 2003
1385
1984
612 1994
990 2004
1446
1985
531 1995
968 2005
1469
1986
671 1996
1061 2006
1502
1987
604.5 1997
977 2007
1689
1988
633 1998
1092
Analysis
• Claim: as years increase, farmers will grow
larger and larger pumpkins because of
genetic modification biology
• Warrant: Pumpkins modified to grow larger
will grow larger
• Backing: Genetic modification of potato
development using Ri T-DNA scholarly article
by G. Ooms, A. Karp, M. M. Burrell, D. Twell
and J. Roberts proved that potatoes and
other vegetables/fruits can be genetically
modified to grow larger
• Qualifier: These data were recorded in the
World Championship which is a valid event
• Rebuttal: N/A
Backing
Warrant
Qualifiers
Qualifiers
The End
Data
Claim
Qualifiers
Qualifiers
Data
Data
Rebuttal
Warrant
Backing
Qualifiers
Qualifiers
Warrant
(Daniel’s Original Model of Toulmin Logic)
Backing