Logical Reasoning

PT124 · S1 · Q3 Science columnist: It is clear

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Science columnist: It is clear why humans have so many diseases in common with cats.

Given

Many human diseases are genetically based.

Cats are genetically closer to humans than are any other mammals except nonhuman primates.

Each of the genes identified so far in cats has an exact counterpart in humans.

Conclusion

The reason humans have so many diseases in common with cats has a genetic basis.

Evaluate

The fact the cats and humans are so genetically similar does create the possibility that our common diseases have a genetic basis. Notice, however, the weakness in the first premise. The fact that “many” (i.e., some) diseases are genetically based makes it possible that most human diseases are not genetically based, such as ones based on bacteria and viruses. It’s possible that the diseases we share in common with cats are based on bacteria and viruses as well.

3.

Which one of the following, if true, most weakens the science columnist's explanation for the claim that humans have so many diseases in common with cats?

  1. Cats have built up resistance

    Too Weak

    This doesn’t change the fact that cats still have these diseases in common with humans. Furthermore, this ignores whether these disease have a genetic, bacterial, or viral basis.

    2% picked this

  2. Correct

    Most diseases that humans have

    Why this is right

    This makes it much less likely that the reason that humans and cats have so many diseases in common is genetically based.

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

    89% picked this

  3. Cats have more diseases in

    Too Weak

    This requires a further assumption about the genetic similarity of cats and humans and of cats and nonhuman primates. We know that humans are closer to nonhuman primates than to cats, but we do not know whether cats are closer to humans or to nonhuman primates.

    3% picked this

  4. Many of the diseases humans

    Premise Support

    This increases the number of diseases common to both humans and cats, but doesn’t offer any suggestion for the basis of those diseases.

    2% picked this

  5. Humans have more genes in

    Premise Support

    This supports the second premise comparing the genetic similarity between humans and cats with the similarity between humans and nonhuman primates.

    3% picked this

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