Module 2: Deductive or Non-deductive

Question 1

This pasture can support three sheep per acre and we have 500 acres. So there’s room enough for our 800 sheep.

Answer 1

Deductive.

Question 2

Our neighbour’s lights are on, so he must be at home.

Answer 2

Non-deductive

Question 3

We are fully entitled to assert that this law is constitutional. The reasons are plain. Surely, our foremost constitutional experts are not all wrong. It is clear, however, that either this law is validated by our constitution or section 21 has been radically misinterpreted by the lower court. As you know, if that section is so misinterpreted, our foremost constitutional experts are indeed all mistaken.

Answer 3

Deductive

Question 4

Whether or not God exists is one of the things we will never know in this life. After all, the question of the existence of God has been considered by some of the best minds since time immemorial. Neither a satisfactory proof of God’s existence not a convincing proof that God does not exist has been produced in spite of the great skill of those who have put life’s labour to the task.

Answer 4

Non-deductive

Question 5

I bet you value your mind more than your legs. Here’s why: if you had no legs, you could still have a good time. If your mind was totally gone, you could not have a good time. People usually value the things they need to have a good time more than they value the things they can do without and still have a good time.

Answer 5

Non-deductive cus they use the word “usually”

Question 6

Marijuana should not be legalized. That’s because sustained use of marijuana worsens a person’s memory, and nothing that adversely affects one’s mental abilities should be legalized.

Answer 6

Deductive

Question 7

Young women who eat foods rich in animal fat may be increasing their risk of breast cancer, a new study has found. Researchers have long suspected a link between fatty diets and breast cancer, but previous studies couldn’t establish one. This new study, a large one involving more than 90,000 nurses, found no link between breast cancer and fats from plants, such as olive oil. But it did find that women who ate more red meat and high-fat dairy products showed a significantly increased risk of getting the disease.

Answer 7

Non-deductive

Question 8

She never takes her eyes off him in a crowd, and she is continually restless when he is out of town. At any opportunity, she will introduce his name in a conversation. And no other men has ever occupied her attention for so long. You can tell she is in love with him.

Answer 8

Non-deductive

Question 9

Either the university budget will increase or the quality of its library holdings will be undermined. If the university budget increases, the opportunities for students will be better. If the quality of the university library holdings is undermined, then great care will be needed to protect its reputation. So either the opportunities for students will be better or great care will be needed to protect the university’s reputation.

Answer 9

Deductive

Question 10

I think Bill is annoyed, because he tenses up whenever he sees me and never invites me for coffee the way he used to. Although he still says hello and we work fairly effectively together, he just seems annoyed.

Answer 10

Non-deductive

Question 11

Deductive arguments

Answer 11

• “bomb-proof”
• logical
• valid

Question 12

Non-deductive arguments

Answer 12

• probabilistic (probable but not non-conclusive evidence)
• is like a bet
• “likely” “plausible”
• with a good one, premise is T then concl is T but you can also accept it even if the concl is False