John: For 40 years, fluoride

Answer choices

1. A

   Out of Scope: other people2% picked this

   John does not consider how others besides himself are affected by

   We can't complain about anything being left out of an argument, unless the thing being left out is relevant to the conclusion being drawn. But since the conclusion is only about John, there's no reason his premises need to consider how other people are affected by fluoridated water.

   2%
2. B

   Out of Scope: other diseases1% picked this

   John does not consider whether fluoridated water causes

   We can't complain about anything being left out of an argument, unless the thing being left out is relevant to the conclusion being drawn. But since the conclusion is only about John developing bone cancer, there's no reason his argument needs to consider other diseases.

   1%
3. C

   Not an Objection2% picked this

   John does not consider whether there were any brief periods during the 40 years in which fluoride was

   This answer is zooming in on a background claim that wasn't even part of the logic. It wouldn't hurt this argument at all if there have been brief periods during the last 40 years in which fluoride wasn't added.

   2%
4. D

   Out of Scope: positive effects5% picked this

   John does not focus on the positive effects that fluoridated water

   If John's conclusion were some broad statement like, "Thus, the city should not fluoridate the public's drinking water", then adjudicating that claim would involve assessing all the pro's and con's of fluoridating water. We'd have to weigh the potentially increased risk of bone cancer against all the positive things that fluoridated water bring us. But the conclusion is narrowly about John and his risk of bone cancer. Nothing else is relevant to adjudicating that claim other than "would he or wouldn't he be sure not to develop bone cancer."

   5%
5. E

   Correct90% picked this

   John does not consider the possibility of other causes of

   Why this is right

   John seems to think that if he stops drinking fluoridated water, then and only then will he be sure not to develop bone cancer. This answer objects by saying, "there are other possible causes of bone cancer, dude. Cutting fluoridated water out of your diet might lower your risk of bone cancer, but you can't be sure you're not going to develop bone cancer because there are other potential causes of bone cancer."

   Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

   90%