Categorical Logic: Testing Syllogisms for Validity Using the (Modern) Venn Diagramming Method (Baronett's "Logic" 2nd ed.)

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Most people are reasonable. No political zealots are reasonable. So, some people are not political zealots.

The argument in standard form:

No political zealots are reasonable people.
Some people are reasonable people.
Some people are not political zealots.

No P are M
Some S are M
Some S are not P

Valid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Rainy days are perfect for curling up with a good book. Today isn't rainy. So, today isn't a perfect day for curling up with a good book.

The argument in standard form:

All rainy days are days perfect days for curling up with a good book.
No days identical with today are rainy days.
No days identical with today are perfect days for curling up with a good book.

All M are P
No S are M
No S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

No good deed goes unpunished. No murder is a good deed. So, no murder goes unpunished.

The argument in standard form:

No good deed is an act that goes unpunished.
No murder is a good deed.
No murder is an act that goes unpunished.

No M are P
No S are M
No S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Novels aren't biographies, but they are works of fiction. Therefore, biographies are not works of fiction.

The argument in standard form:

All novels are works of fiction.
No novels are biographies.
No biographies are works of fiction.

All M are P
No M are S
No S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Many predators are marine animals. No cats are marine animals. So, at least some cats are not predators.

The argument in standard form:

Some predators are marine mammals.
No cats are marine mammals.
Some cats are not predators.

Some P are M
No S are M
Some S are not P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

At least some Tesla cars are made well. That's because Tesla cars aren't inexpensive. Most expensive things are made well.

The argument in standard form:


Some expensive things are well made things.
All Tesla cars are expensive things.
Some Tesla cars are well made things.

Some M are P
All S are M
Some S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

No citizen has a legal right to a home. All citizens have a legal right to vote. So, a legal right to vote does not guarantee a legal right to a home.

The argument in standard form:

No citizens are individuals with a legal right to a home.
All citizens are individuals with a legal right to vote.
No individuals with a legal right to vote are individuals with a legal right to a home.

No M are P
All M are S
No S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Many wartime refugees prefer to return to their home country. Any wartime refugee is fleeing from violence. Consequently, many people who flee from violence are people who prefer to return to their home country.

The argument in standard form:

Some wartime refugees are people who prefer to return to their home country.
All wartime refugees are people who flee from violence.
Some people who flee from violence are people who prefer to return to their home country.

Some M are P
All M are S
Some S are P

Valid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Many drugs are therapeutic. Heroin is a drug. So, heroin is therapeutic.

The argument in standard form:

Some drugs are therapeutic drugs.
All drugs identical to heroin are drugs.
All drugs identical to heroin are therapeutic drugs.

Some M are P
All S are M
All S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Some alcoholic beverages are bitter. Some bitter things are good for you. So, some alcoholic beverages are good for you.

The argument in standard form:

Some bitter things are good things for you.
Some alcoholic beverages are bitter things.
Some alcoholic beverages are good things for you.

Some M are P
Some S are M
Some S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

Gremlins aren't real. Dogs are real. So, dogs aren't gremlins.

The argument in standard form:

No gremlins are real things.
All dogs are real things.
No dogs are gremlins.

No P are M
All S are M
No S are P

Valid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

No sensitive person passes up the opportunity to watch a beautiful sunset. Anyone who passes up the opportunity to watch a beautiful sunset lacks appreciation for the finer things in life. So, no sensitive person lacks appreciation for the finer things in life.

The argument in standard form:

All persons who pass up the opportunity to watch a beautiful sunset are persons who lack appreciation for the finer things in life.
No sensitive persons are persons who pass up the opportunity to watch a beautiful sunset.
No sensitive persons are persons who lack appreciation for the finer things in life.

All M are P
No S are M
No S are P

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):


Some musical instruments are made from wood. Some things made from wood are beautiful works of craftsmanship. Consequently, some musical instruments are beautiful works of craftsmanship.

The argument in standard form:

Some things made from wood are beautiful works of craftsmanship.
Some musical instruments are things made from wood.
Some musical instruments are beautiful works of craftsmanship.

Some M are P
Some S are M
Some S are P

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):

No pigs fly. No cats fly. So, no pigs are cats.

The argument in standard form:


No cats are flying animals.
No pigs are flying animals.
No pigs are cats.

No P are M
No S are M
No S are P

Invalid!

1) Rewrite the following argument in standard form. 2) Construct a Venn diagram to determine whether or not the argument is valid. Remember to use the modern interpretation of the universal proposition (i.e., do not assume existential import):


Many people are insomniacs. Some insomniacs are not happy. So, many people are not happy.

The argument in standard form:

Some insomniacs are not happy people.
Some people are insomniacs.
Some people are not happy people.

Some M are not P
Some S are M
Some S are not P

Invalid!