Give me a reason
Definitions
True, Valid, and Sound?
Define it
Law of Reason
100

If 3x = 12, then x = 4.

Multiplication Property of Equality

100

Two angles that have a sum of 180⁰

Supplementary angles

100

Premise 1: All men are mortal. 

Premise 2: Socrates is a man. 

Conclusion: Socrates is mortal. 

True, valid, and sound

100

Type of reasoning that draws a conclusion after observing patterns in several examples

Inductive reasoning

100

If a number is even, then it is divisible by 2.
15 is not divisible by 2.
Therefore, 15 is not even.

Modus tollens

200

If 27⁰ = x, then x = 27⁰

Symmetric Property of Equality

200

Two angles that have a sum of 90⁰

Complementary angles

200

Premise 1: All birds are reptiles. 

Premise 2: A sparrow is a bird. 

Conclusion: A sparrow is a reptile. 

Valid (the conclusion follows logically), but unsound (Premise 1 is false).

200

Given p → q, the ___ of the statement is q → p. 

Converse

200
If you pass your driver′ s test, you get your license. You passed your driver′ s test. 

You get your license.

Modus ponens

300

If AB = CD, CD = EF

Then AB = EF

Substitution or Transitive Property of Equality 

300

Nonadjacent angles of two intersecting lines

Vertical angles

300

Premise 1: The sky is blue.

Premise 2: Water boils at 100°C.

Conclusion: Therefore, the grass is green.

Argument is invalid. Premises do not support the conclusion. Unsound.

300

Given p → q, the ___ of the statement is not p → not q.

Inverse

300

If line l ∥ line m and line m ∥ line n,
then line l ∥ line n.

Transitivity

400

If angle A is congruent to angle B and angle A = 50⁰, then angle B = 50⁰.

Definition of congruent angles.

400

Two angles that share a common ray and endpoint but no common interior points

Adjacent angles

400

Premise 1: The Constitution states that anyone who has ever owned a cat is legally disqualified from running for President of the United States.

Premise 2: Candidate Jones has owned three cats in his lifetime.

Conclusion: Therefore, Candidate Jones is legally disqualified from running for President of the United States.

Valid but premise 1 is untrue; therefore, the argument is unsound

400

Given p → q, the ___ of the statement is 

not q → not p.

Contrapositive

400

If the plant gets enough sunlight, then it will grow tall.
The plant did not grow tall.
Therefore, it did not get enough sunlight.

Modus tollens

500


Angle Addition Postulate

500

Two angles that have the same measure

Congruent angles

500

Premise 1: Senator Smith served honorably as a pilot in the United States Air Force.

Premise 2: The federal highway budget increased by four percent last fiscal year.

Conclusion: Senator Smith's proposed corporate tax reform bill will lower the national deficit.

True premises, Invalid, Unsound

500

The biconditional p ↔ q is true when 

(p → q) Λ ______.

q → p

500

If a triangle is equilateral, then all three of its angles measure 60°.
Triangle ABC is equilateral.
Therefore, all three angles of triangle ABC measure 60°.

Modus ponens