« on: September 30, 2008, 11:14:32 AM »
This is justify the conclusion, and the correct answer choice should SUFFICIENTLY allow the conclusion to be properly drawn in conncetion with the premises given in the stimulus. The conclusion is, "We cannot in any real sense mistreat plants." You need to justify this conclusion using the premise given.
Premise 1: Plants do not have nervous system.
Plants -> ~NS (Nervous System)
Premise 2: Having a nervous system is necessary to experience pain.
Pain -> NS
Conclusion: We cannot in any real sense mistreat plants.
Plants -> ~Mistreat
Based on the premises given and looking at the conclusion, you'll note that there is a "jump." Something is missing and just with the information within the stimulus alone will not allow one to arrive at the conclusion that "Plant cannot be mistreated."
Try connecting premise 1 and 2 by using the contrapositive for premise 2:
Premise 2 contrapositive: ~NS -> ~Pain
Connect premise 2 and 1: Plants -> ~NS -> ~Pain
Looking at answer choice D, it says "Only organisms that can experience pain can be mistreated."
D: Mistreat -> Pain
Contrapositive: ~Pain -> ~Mistreat
Connect this contrapositive to the premise 1 and 2, and you get:
Plants -> ~NS -> ~Pain -> ~Mistreat
Or by transitive property:
Plants -> ~Mistreat (OUR CONCLUSION)
Note that choice D includes ALL ORGANISM, which is not necessary for us to reach the conclusion, but it is SUFFICIENT for us to reach the conclusion noted in the stimulus. On the side note, other choice like "Only organisms with nervous system can be mistreated" can also work.
Choice B is incorrect since it's somewhat of a repeat of premise 2. We needed something to bridge the jump between the premises and conclusion. Hope this helps.