Understanding Reasoning

Which of the following is an example of deductive reasoning?

• All birds can fly. Penguins are birds. Therefore, penguins can fly.

• All mammals have lungs. A whale is a mammal. Therefore, a whale has lungs.

• I saw three swans today, and they were all white. Therefore, all swans are white.

• The grass is wet. It must have rained last night.

Identify the type of reasoning used in the following scenario: "Every time I eat peanuts, I start to sneeze. I must be allergic to peanuts."

• Deductive reasoning

• Inductive reasoning

• Abductive reasoning

• None of the above

Which scenario best illustrates abductive reasoning?

• All dogs bark. Max is a dog. Therefore, Max barks.

• The sun rises every morning. Therefore, the sun will rise tomorrow.

• The lights are off in the house. The family must be out.

• If it rains, the ground gets wet. It is raining. Therefore, the ground is wet.

Evaluate the effectiveness of the reasoning: "If a plant is green, it is healthy. This plant is green. Therefore, it is healthy."

• Highly effective, as it is based on a universal truth.

• Somewhat effective, but not all green plants are healthy.

• Ineffective, as the color of a plant does not determine its health.

• Effective, because all plants are green.

Apply deductive reasoning to solve this problem: "All squares are rectangles. A shape is a square. What can you conclude about the shape?"

• The shape is a circle.

• The shape is a rectangle.

• The shape is a triangle.

• The shape is a pentagon.

Analyze the reasoning: "I have seen 10 dogs today, and they were all barking. Therefore, all dogs bark."

• Deductive reasoning

• Inductive reasoning

• Abductive reasoning

• None of the above

Which of the following is an example of inductive reasoning?

• All cats have tails. This animal is a cat. Therefore, it has a tail.

• The last five times I ate ice cream, it was delicious. Therefore, ice cream is always delicious.

• If it is snowing, it is cold outside. It is snowing. Therefore, it is cold outside.

• The car won't start. The battery might be dead.

Apply abductive reasoning to this scenario: "The window is broken, and there are footprints outside. What might have happened?"

• A bird flew into the window.

• Someone broke the window and entered the house.

• The wind was strong and broke the window.

• The window broke on its own.

Evaluate the reasoning: "If it rains, the streets get wet. The streets are wet. Therefore, it rained."

• Highly effective, as wet streets always mean it rained.

• Somewhat effective, but wet streets can be caused by other factors.

• Ineffective, as wet streets never mean it rained.

• Effective, because rain is the only cause of wet streets.

Which reasoning type is used here: "The cake is missing from the table. The dog has crumbs on its face. The dog must have eaten the cake."

• Deductive reasoning

• Inductive reasoning

• Abductive reasoning

• None of the above