CT8 Classical Logic Syllogisms
CT8 Classical Logic Syllogisms
Through systematic identification of major and minor premises and terms, the figure of the reasoning and the extensions of the premise and conclusion (the result of which gives the standard form, for instance AAA-1 for Barbara), try to determine to which diagram thefollowing syllogisms belong:
All spiders have ten legs.
Ten-legged animals have wings.
Therefore, all spiders have wings.
Some nutritious meals are vegetarian delicacies.
All nutritious meals are balanced meals.
Some balanced meals are vegetarian delicacies.
Some beloved pets are Labradoodles.
All Labradoodles are dogs.
Some dogs are beloved pets.
Some local hospitals are not academic hospitals.
All local hospitals are healthcare institutions.
Some healthcare institutions are not academic hospitals.
Use a Venn diagram to determine whether the following syllogisms are valid:
Every living being is mortal.
Every human being is a living being.
Therefore, every human being is mortal.
Some psychologists are psychoanalysts.
No psychologists are charlatans.
Therefore, some psychoanalysts are not charlatans.
Some gestures are obscene.
Some movements are not gestures.
Therefore, some movements are not obscene.
Make an argument map of the following argumentation (a sorites, or chain of syllogisms):
All writers who understand human nature are clever. No one is a true poet unless he can stir the hearts of men. Shakespeare wrote Hamlet. No writer who does not understand human nature can stir the hearts of men. None but a true poet could have written Hamlet. Conclusion: Shakespeare was clever.
Is this argumentation valid? If you have time left, try to demonstrate this with
Of the following now familiar syllogisms, indicate which is the major term, which is the minor term and which are themajor and minor premises.
Think of an example of the DARII and FERIO diagrams.
Think of an example of the CESARE, DISAMIS and BRAMANTIP diagrams.
Rule 1: The middle term must be distributed at least once.
Rule 2: If a term is distributed in the conclusion, then it must be
distributed in a premise.
Rule 3: Two negative premises are not allowed.
Rule 4: A negative premise requires a negative conclusion, and a negative conclusion
requires a negative premise.
Rule 5: If both premises are universal, the conclusion cannot be particular.
All three statements are standard-form categorical propositions.
The two occurrences of each term are identical.
Each term is used in the same sense throughout the argument.
The major premise is listed fi rst, the minor premise second, and the conclusion last.
= predicate of conclusion
= subject of conclusion
= term present in both premises
Only reasoning (argumentation) that contains premises and a conclusion can be
valid or invalid. The claims that serve as the premises and the conclusion can be
true or false. Verify that the interaction of these functions is evident from the
Distinction of deductive and inductive reasoning
Standard Forms of Syllogisms
principle of non-contradiciton
middle term as relating two concepts
the incorrect use of negation
A shift in the field of reality to which the terms refers
an ambiguity in a term
rules for a valid syllogism
A syllogism can be seen as a formalised appeal to the principle of non-contradiction. The theory of the syllogism is about the question of when this appealis justified, and when it is not.