PHL 410 Textbook Exercise 5.4

For each of the following examples of induction or analogical reasoning, decide whether or not the argument is valid. Explain your answer.

The first one is an example.

A random sample of 1,000 Oregonians found that 51% favored the war in Iraq. Therefore, 49% of all Oregonians are opposed to the war.
 

Invalid. Fails to be an appropriate sample because, even though the sample is random and objective, it does not tell us about who opposes the war in Iraq (e.g. people could be indifferent or conflicted over the issue).

 

1. “Now if we survey the universe, so far as it falls under our knowledge, it bears a great resemblance to an animal or organized body, and seems actuated with a like principle of life and motion. A continual circulation of matter in it produces no disorder: a continual waste in every part is incessantly repaired; the closest sympathy is perceived throughout the entire system: and each part or member, in performing its proper offices, operated both to its own preservation and to that of the whole. The world, therefore, I infer, is an animal, and the Deity is the soul of the world actuating it, and actuated by it.” (Hume, 1779, 82-3)

 

2. Most long-time Democrats are opposed to a long military involvement in Iraq. My friend Elmer is a long-time Democrat so my friend Elmer is someone who opposes a long military involvement in Iraq.

 

3. A survey of San Diegans was taken outside of the football stadium directly after a Charger victory. The survey sampled over 5,000 people and was restricted to only San Diegans of voting age. That survey revealed that 75% of San Diegans support the public financing of a new stadium for the Chargers to play in. This survey therefore seems to show that the stadium measure will pass easily.

 

4. Most waiters and waitresses that work in downtown, when tips are factored in, make over $30 an hour. None of my good friends make over $30 an hour, even when tips are factored in. Therefore it is safe to conclude that none of my good friends are waiters or waitresses that work in downtown.

 

5. A survey was conducted of women’s attitudes toward education. A sample was selected randomly from among a group of Minnesota women who had dropped out of high school. Based on this study, funded by the “Protect Traditional Values Action Committee,” we have determined that among Minnesota women, 82% feel that education had little or no effect on their quality of life.

 

6.  “If you cut up a large diamond into little bits, it will entirely lose the value it had as a whole; and an army divided up into small bodies of soldiers, loses all its strength. So a great intellect sinks to the level of an ordinary one, as soon as it is interrupted and disturbed, its attention distracted and drawn off from the matter in hand: for its superiority depends upon its power of concentration-of bringing all its strength to bear upon one theme, in the same way as a concave mirror collects into one point all the rays of light that strike upon it.” (Schopenhauer, 1908, 127-8)

Textbook Exercise 5.4

For each of the following examples of induction or analogical reasoning, decide whether or not the argument is valid in light of the standards discussed in 5.2 and 5.3. Explain your answer.

The first one is an example.

A random sample of 1,000 Oregonians found that 51% favored the war in Iraq. Therefore, 49% of all Oregonians are opposed to the war. Invalid. Fails to be an appropriate sample because, even though the sample is random and objective, it does not tell us about who opposes the war in Iraq (e.g. people could be indifferent or conflicted over the issue).

1. “Now if we survey the universe, so far as it falls under our knowledge, it bears a great resemblance to an animal or organized body, and seems actuated with a like principle of life and motion. A continual circulation of matter in it produces no disorder: a continual waste in every part is incessantly repaired; the closest sympathy is perceived throughout the entire system: and each part or member, in performing its proper offices, operated both to its own preservation and to that of the whole. The world, therefore, I infer, is an animal, and the Deity is the soul of the world actuating it, and actuated by it.” (Hume, 1779, 82-3)

2. Most long-time Democrats are opposed to a long military involvement in Iraq. My friend Elmer is a long-time Democrat so my friend Elmer is someone who opposes a long military involvement in Iraq.

3. A survey of San Diegans was taken outside of the football stadium directly after a Charger victory. The survey sampled over 5,000 people and was restricted to only San Diegans of voting age. That survey revealed that 75% of San Diegans support the public financing of a new stadium for the Chargers to play in. This survey therefore seems to show that the stadium measure will pass easily.

4. Most waiters and waitresses that work in downtown, when tips are factored in, make over $30 an hour. None of my good friends make over $30 an hour, even when tips are factored in. Therefore it is safe to conclude that none of my good friends are waiters or waitresses that work in downtown.

5. A survey was conducted of women’s attitudes toward education. A sample was selected randomly from among a group of Minnesota women who had dropped out of high school. Based on this study, funded by the “Protect Traditional Values Action Committee,” we have determined that among Minnesota women, 82% feel that education had little or no effect on their quality of life.

6. “If you cut up a large diamond into little bits, it will entirely lose the value it had as a whole; and an army divided up into small bodies of soldiers, loses all its strength. So a great intellect sinks to the level of an ordinary one, as soon as it is interrupted and disturbed, its attention distracted and drawn off from the matter in hand: for its superiority depends upon its power of concentration-of bringing all its strength to bear upon one theme, in the same way as a concave mirror collects into one point all the rays of light that strike upon it.” (Schopenhauer, 1908, 127-8)