Logical Reasoning

PT125 · S4 · Q7 In an experiment, biologists

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In an experiment, biologists repeatedly shone a bright light into a tank containing a sea snail and simultaneously shook the tank.

Evidence

In an experiment, biologists repeatedly shone a bright light into a tank containing a sea snail and simultaneously shook the tank.

The snail invariably responded by tensing its muscular "foot;" a typical reaction in sea snails to ocean turbulence.

After several repetitions of this procedure, the snail tensed its "foot" whenever the biologists shone the light into its tank, even when the tank was not simultaneously shaken.

Conclusion

Therefore, the snail must have learned to associate the shining of the bright light with the shaking of the tank.

Evaluate

The argument offers one explanation for the observed tense “foot.” However, other possible explanations do exist and would need to be ruled out in order to affirm the explanation put forward in the argument’s conclusion. So the argument assumes that the bright light by itself would not normally induce the snail to tense its "foot."

Which one of the following is an assumption required by the argument?

All sea snails react to
Too Strong
The argument suggests that the reaction of the sea snail is typical, but it need not be the case that all sea snails would react the same way.
1% picked this
Sea snails are not ordinarily
Out of Scope
Whether the experience is common or rare is irrelevant. The question is whether the sea snail would normally respond to the bright light by tensing its "foot."
5% picked this
The sea snail used in
Out of Scope - Opposite Group
Other sea snails are not relevant to this argument about one specific sea snail.
3% picked this
Correct
The appearance of a bright
Why this is right
This answer rules out a possible alternative explanation for the sea snail's reaction. In order to infer one explanation of the observed tense “foot” the argument must assume that something else does not explain it.
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.
86% picked this
Tensing of the muscular "foot"
Out of Scope
The argument is about whether the sea snail demonstrated a learned response to shining a bright light, not about whether tensing of the "foot" in response to ocean turbulence is learned or instinctual.
5% picked this

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