PT 58, S2, Q11, Recent studies indicate the correlation...

[bbirdwell]

This is a great problem, largely because it's representative of a common argumentative form (the causal argument), and several of the choices dance around the true flaw without correctly naming it.

The quicker one becomes at recognizing causal arguments, the better. This argument is a bit of a black sheep in that the logic is based on cause/correlation, but the conclusion is actually that a causal relationship does NOT exist. The breakdown is below:

Conclusion: No causal connection between damage to chromosome 6 and schizophrenia

Premises: There is correlation between damage to chromosome 6 and schizophrenia.
Some ppl with schizophrenia have no damage to chromosome 6.
Some pp. with damage to chromosome 6 have no schizophrenia.

Immediately upon recognizing a causal construction like this, one should think "What about other causes -- does the apparent fact that schizophrenia can be caused by things other than chromosome damage indicate that it's NEVER caused by chromosome damage (or never causes the chromosome damage itself)? And likewise, is the fact that chromosome damage does not ALWAYS lead to schizophrenia enough to conclude that it NEVER does?"

Answer choice (A) addresses these concerns. The argument does indeed ignore this possibility, for if it's true that NOT ALL types of chromosome 6 damage lead to schizophrenia, then it's possible that SOME damage to chromosome 6 does in fact cause the disorder.

(B) No, in fact the argument states explicitly that some schizophrenics have no chromosome damage.

(C) This is not a sampling flaw, though sampling flaws occur with regularity on the LSAT.

(D) No, this is not a necessary/sufficient or cause/effect reversal.

(E) No, in fact, the arguments conclusion contradicts this altogether.

Pretty snappy, eh?