Is there a causal relationship between smoking and lung cancer? Research consistently shows a strong correlation between smoking and the...

Understanding the Question

The question asks: "Is there a causal relationship between smoking and lung cancer?"

This is a yes/no question. To answer with certainty, we must be able to definitively say either YES (smoking causes lung cancer) or NO (smoking does not cause lung cancer).

Here's the crucial distinction: Correlation ≠ Causation

• Correlation: Two things occur together frequently
• Causation: One thing directly causes the other

For true causation, we need:

1. Evidence of correlation (they occur together)
2. A proven mechanism (how one causes the other)
3. Alternative explanations ruled out

To have sufficiency in this DS question, we need enough information to definitively establish whether causation exists or not.

Analyzing Statement 1

Statement 1: "Research consistently shows a strong correlation between smoking and the development of lung cancer."

This tells us that smokers develop lung cancer more frequently than non-smokers. However, correlation alone never proves causation.

Consider these equally possible scenarios:

• Scenario A: Smoking directly damages lung cells → cancer develops (TRUE CAUSATION)
• Scenario B: Genetic factor X → makes people more likely to smoke AND more susceptible to cancer (NO DIRECT CAUSATION)
• Scenario C: Smokers live in polluted areas → pollution causes cancer (INDIRECT RELATIONSHIP)

Since Statement 1 only establishes correlation, we cannot distinguish between these scenarios. We cannot definitively answer YES or NO to the causation question.

Statement 1 alone is NOT sufficient.

[STOP - Not Sufficient!] This eliminates choices A and D.

Analyzing Statement 2

Important: We now forget Statement 1 completely and analyze Statement 2 independently.

Statement 2: "Some medical researchers support a proposed mechanism by which smoking could cause lung cancer."

Let's examine the key words:

• "Some" researchers (not all or most)
• "Proposed" mechanism (not proven)
• Smoking "could" cause cancer (possibility, not certainty)

This gives us a theoretical pathway for causation, but with significant uncertainty. Without knowing if this mechanism is:

• Actually correct
• Widely accepted by the scientific community
• Proven through rigorous testing

...we cannot definitively answer our yes/no question.

Statement 2 alone is NOT sufficient.

[STOP - Not Sufficient!] This eliminates choice B (and D is already eliminated).

Combining Both Statements

Now let's use both statements together:

• From Statement 1: Strong correlation exists
• From Statement 2: A proposed mechanism exists (with some support)

Even combined, can we definitively answer whether smoking causes lung cancer?

What we have:

• Evidence that smoking and lung cancer occur together
• A possible explanation for how one might cause the other

What we still lack:

• Proof that the mechanism is correct
• Elimination of alternative explanations
• Scientific consensus (we only have "some" support)

The correlation could still be explained by non-causal factors (like our Scenarios B and C from earlier). The proposed mechanism remains unproven—it's just a theory with partial support.

For definitive causation, we would need:

• The mechanism to be proven correct
• Alternative explanations to be ruled out
• Broad scientific consensus, not just "some" support

The statements together are NOT sufficient.

[STOP - Not Sufficient!] This eliminates choice C.

The Answer: E

Neither statement alone nor both statements together provide sufficient information to determine whether there is a causal relationship between smoking and lung cancer.

We can establish correlation and identify a possible mechanism, but we cannot definitively prove or disprove causation.

Answer: E - Both statements together are still not sufficient.