狠狠撸

狠狠撸Share a Scribd company logo

Monty Python and the Quest for the Perfect Fallacy - arranged by Valerie D. Van Curen

?Download as PPTX, PDF?
?
Val Van Curen
Val Van Curen

This document summarizes the logical fallacies in the "Witch's Trial Argument" presented in Monty Python and the Quest for the Perfect Fallacy. It analyzes each part of the argument in turn, finding that all parts commit the fallacy of the undistributed middle, where it incorrectly concludes that all things in one category (witches) are in another (things that weigh as much as a duck) based on both categories sharing a common property (weighing as much as a duck) without establishing that the categories are equivalent.

1 of 19
Downloaded 54 times
MONTY PYTHON AND THE QUEST FOR THE PERFECT FALLACY The Witch’s Trial Argument Activity adapted from Annenberg Classroom Fact Check FactCheckEd.org
THE ARGUMENT
A L L W I T C H E S A R E T H I N G S T H AT C A N BU R N.
ALL THINGS THAT CAN BURN A R E M A D E O F W O O D.
THEREFORE, ALL WITCHES A R E M A D E O F W O O D.
ALL THINGS THAT ARE MADE OF WOOD A R E T H I N G S T H A T C A N F L O A T.
ALL THINGS THAT WEIGH AS MUCH AS A D U C K A R E T H I N G S T H A T C A N F L O A T.
SO, ALL THINGS THAT WEIGH AS MUCH AS A D U C K A R E T H I N G S T H A T A R E M A D E O F W O O D.
THEREFORE, ALL WITCHES ARE THINGS THAT WEIGH AS MUCH AS A DUCK.
THIS IS A THING THAT WEIGHS AS MUCH AS A DUCK.
THEREFORE, THIS THING IS A WITCH.
FIRST ARGUMENT PART ? All witches are things that can burn. ? All things that can burn are made of wood. ? Therefore, all witches are made of wood. Is this a valid argument?
T H I S I S A VA L I D A R G U M E N T. That is, (3) really does follow logically from (1) and (2). That’s not to say that it’s an especially convincing argument because premise (2) is rather obviously false. Still, if (2) were true, then the conclusion would have to be true as well. So this step is valid but unsound. 1. All witches are things that can burn. 2. All things that can burn are made of wood. 3. Therefore, all witches are made of wood.
SECOND ARGUMENT PART ? All things that are made of wood are things that can float. ? All things that weigh as much as a duck are things that can float. ? So, All things that weigh as much as a duck are things that are made of wood. Is this a valid argument?
THIS IS A FALLACY This argument commits the fallacy of the undistributed middle. The structure of the argument is the old A. All things that are made of wood are things that can float. B. All things that weigh as much as a duck are things that can float. familiar ? ? ? All A is C. All B is C. Therefore, all A is B. And that, of course, isn’t a valid argument. C. So, All things that weigh as much as a duck are things that are made of wood.
THIRD ARGUMENT PART ? Therefore, all witches are made of wood. ? So all things that weigh as much as a duck are things that are made of wood. ? Therefore, all witches are things that weigh as much as a duck. Is this a valid argument?
THIS IS A FALLACY This argument has the same ? All witches are made of wood. problem as the second argument. ? So all things that weigh as much as a duck are things that are made It’s also an undistributed middle. ? All A is C. ? All B is C. ? Therefore, all A is B. of wood. ? Therefore, all witches are things that weigh as much as a duck.
FINAL ARGUMENT PART ? All witches are things that weigh as much as a duck. ? This thing is a thing that weighs as much as a duck. ? Therefore, this thing is a witch. Is this a valid argument?
THIS IS A FALLACY The final argument: Yes, once again, it’s an undistributed middle . All A is C. All B is C. Therefore, all A is B. ? All witches are things that weigh as much as a duck. ? This thing is a thing that weighs as much as a duck. ? Therefore, this thing is a witch.

More Related Content

Monty Python and the Quest for the Perfect Fallacy - arranged by Valerie D. Van Curen

  • 1. MONTY PYTHON AND THE QUEST FOR THE PERFECT FALLACY The Witch’s Trial Argument Activity adapted from Annenberg Classroom Fact Check FactCheckEd.org
  • 3. A L L W I T C H E S A R E T H I N G S T H AT C A N BU R N.
  • 4. ALL THINGS THAT CAN BURN A R E M A D E O F W O O D.
  • 5. THEREFORE, ALL WITCHES A R E M A D E O F W O O D.
  • 6. ALL THINGS THAT ARE MADE OF WOOD A R E T H I N G S T H A T C A N F L O A T.
  • 7. ALL THINGS THAT WEIGH AS MUCH AS A D U C K A R E T H I N G S T H A T C A N F L O A T.
  • 8. SO, ALL THINGS THAT WEIGH AS MUCH AS A D U C K A R E T H I N G S T H A T A R E M A D E O F W O O D.
  • 9. THEREFORE, ALL WITCHES ARE THINGS THAT WEIGH AS MUCH AS A DUCK.
  • 10. THIS IS A THING THAT WEIGHS AS MUCH AS A DUCK.
  • 11. THEREFORE, THIS THING IS A WITCH.
  • 12. FIRST ARGUMENT PART ? All witches are things that can burn. ? All things that can burn are made of wood. ? Therefore, all witches are made of wood. Is this a valid argument?
  • 13. T H I S I S A VA L I D A R G U M E N T. That is, (3) really does follow logically from (1) and (2). That’s not to say that it’s an especially convincing argument because premise (2) is rather obviously false. Still, if (2) were true, then the conclusion would have to be true as well. So this step is valid but unsound. 1. All witches are things that can burn. 2. All things that can burn are made of wood. 3. Therefore, all witches are made of wood.
  • 14. SECOND ARGUMENT PART ? All things that are made of wood are things that can float. ? All things that weigh as much as a duck are things that can float. ? So, All things that weigh as much as a duck are things that are made of wood. Is this a valid argument?
  • 15. THIS IS A FALLACY This argument commits the fallacy of the undistributed middle. The structure of the argument is the old A. All things that are made of wood are things that can float. B. All things that weigh as much as a duck are things that can float. familiar ? ? ? All A is C. All B is C. Therefore, all A is B. And that, of course, isn’t a valid argument. C. So, All things that weigh as much as a duck are things that are made of wood.
  • 16. THIRD ARGUMENT PART ? Therefore, all witches are made of wood. ? So all things that weigh as much as a duck are things that are made of wood. ? Therefore, all witches are things that weigh as much as a duck. Is this a valid argument?
  • 17. THIS IS A FALLACY This argument has the same ? All witches are made of wood. problem as the second argument. ? So all things that weigh as much as a duck are things that are made It’s also an undistributed middle. ? All A is C. ? All B is C. ? Therefore, all A is B. of wood. ? Therefore, all witches are things that weigh as much as a duck.
  • 18. FINAL ARGUMENT PART ? All witches are things that weigh as much as a duck. ? This thing is a thing that weighs as much as a duck. ? Therefore, this thing is a witch. Is this a valid argument?
  • 19. THIS IS A FALLACY The final argument: Yes, once again, it’s an undistributed middle . All A is C. All B is C. Therefore, all A is B. ? All witches are things that weigh as much as a duck. ? This thing is a thing that weighs as much as a duck. ? Therefore, this thing is a witch.