Validity and Logic Practice Exercises

Vocabulary and structural analysis of logical argument examples evaluated for validity and form.

Argument (1): Socrates Carrot Argument

An argument structured as: 1. Socrates is a man. 2. All men are carrots. 3. Therefore, Socrates is a carrot. Classified as Valid (V).

Argument (2): Labor Day Disjunctive Argument

An argument structured as: 1. Either today is Labor Day, or the building is full. 2. The building isn't full. 3. Therefore, today is Labor Day. Classified as Valid (V).

Argument (3): Green Van Conditional Argument

An argument structured as: 1. If the green van is missing, then Claire is at the beach. 2. The green van is missing. 3. Therefore, Claire is at the beach. Classified as Valid (V).

Argument (4): Jones Divorce Lawyer Argument

An argument structured as: 1. If Jones decided that she is going to get divorced, then she called a lawyer. 2. Jones just called a lawyer. 3. Hence, she has decided she's going to get divorced. Classified as Invalid (IV).

Argument (5): Jeff and Mary Disjunction Argument

An argument structured as: 1. Jeff is playing basketball, or Mary is watching television. 2. Mary is watching television. 3. Therefore, Jeff is playing basketball. Classified as Invalid (IV).

Argument (6): Central High School Survey Argument

An argument structured as: 1. 160 12th graders at Central High School were asked. 2. 75 percent said that they were planning to go to college next year. 3. Therefore, about 75 percent of all the 12th graders at Central High School are probably going to college next year.

Argument (7): Florence and Lisbon Destination Argument

An argument structured as: 1. As vacation destinations, Florence and Lisbon have many similarities: nice weather, historical attractions, and great restaurants. 2. Sarah enjoyed visiting Florence. 3. Therefore, Sarah will probably enjoy visiting Lisbon.

Argument (8): Painting and New Jersey Converse Argument

An argument structured as: 1. If Mary stole the painting, then Jeff is in New Jersey. 2. Therefore, if Jeff is in New Jersey, then Mary stole the painting. Classified as Invalid (IV).

Argument (9): Painting and New Jersey Contrapositive Argument

An argument structured as: 1. If Mary stole the painting, then Jeff is in New Jersey. 2. Therefore, if Jeff is not in New Jersey, then Mary did not steal the painting.

Argument (10): Amy Campus or Moon Argument

An argument structured as: 1. Amy is on campus. 2. Therefore, Amy is on campus, or she is on the moon.

Argument (11): Jack Nap Conjunction Argument

An argument structured as: 1. Jack is taking a nap. 2. Therefore, Jack is taking a nap, and Kate is reading.

Argument (12): Roger Bank Denying Antecedent Argument

An argument structured as: 1. If Roger is in the bank, then Steven is waiting in the apartment. 2. Roger is not in the bank. 3. Therefore, Steven is not waiting in the apartment. Classified as Invalid (IV).

Argument (13): Joan Work Contrapositive Argument

An argument structured as: 1. If Joan is at work, then Kate is sleeping. 2. Therefore, if Kate is not sleeping, then Joan is not at work.

Argument (14): Inverted Chain Hypothetical Syllogism

An argument structured as: 1. If Mary is in the library, then Jeff is watching tv. 2. If Jeff is watching tv, then Claire is taking a nap. 3. Therefore, if Claire is taking a nap, then Mary is in the library.

Argument (15): Standard Hypothetical Syllogism

An argument structured as: 1. If Mary is in the library, then Jeff is watching tv. 2. If Jeff is watching tv, then Claire is taking a nap. 3. Therefore, if Mary is in the library, then Claire is taking a nap.

Argument (16): Combined Hypothetical Syllogism and Contrapositive

An argument structured as: 1. If Mary is in the library, then Jeff is watching tv. 2. If Jeff is watching tv, then Claire is taking a nap. 3. Therefore, if Claire is not taking a nap, then Mary is not in the library.

Argument (17): George and Susan Disjunctive Syllogism

An argument structured as: 1. George is an architect, or Susan is a lawyer. 2. George is not an architect. 3. Therefore, Susan is a lawyer.

Argument (18): Affirming Disjunct Fallacy Argument

An argument structured as: 1. Amy is walking in the park, or Sarah is playing basketball. 2. Amy is walking in the park. 3. Therefore, Sarah is not playing basketball.

Argument (19): Lawn Mowing Conjunction Fallacy Argument

An argument structured as: 1. George is mowing the lawn. 2. Therefore, George is mowing the lawn, and Fred is looking for his coat.

Argument (20): Statistical Sea Lion Argument

An argument structured as: 1. Almost all sea lions live in the Atlantic Ocean around New York and New Jersey. 2. Sammy is a sea lion. 3. Therefore, Sammy lives in the Atlantic Ocean around New York and New Jersey.

Argument (21): Universal Sea Lion Argument

An argument structured as: 1. All sea lions live in the Atlantic Ocean around New York and New Jersey. 2. Sammy is a sea lion. 3. Therefore, Sammy lives in the Atlantic Ocean around New York and New Jersey.