Science journalist: Europa, a moon of Jupiter, is covered with ice. Data recently transmitted by a spacecraft strongl...

tselimovic on March 18, 2015


What is the flaw in the stimulus? The two flaws I picked up on were (1) what if Europe bears life which is not "as we know it" and (2) just because liquid water is necessary for the evolution of life doesn't mean primitive life must have evolved. Thank you.

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Naz on March 18, 2015

Conclusion: "it is likely that at least primitive life has evolved on Europa."

Why? "Life as we know it could evolve only in the presence of liquid water." And we know from recent data that it is very likely that there are oceans of liquid water deep under the ice that covers Europa.

So we know that life requires the presence of liquid water.

L ==> LW
not LW ==> not L

The journalist states that data "strongly suggests" that there is a presence of liquid water beneath the ice. So, this does not necessarily mean that there definitively is liquid water on Europa.

Further, and more importantly, the presence of liquid water is a necessary condition. We know that we cannot conclude anything from a necessary condition. The argument mistakes "the presence of liquid water" for the sufficient condition of the argument and mistakes "there being life" as the "necessary condition."

Remember, a necessary condition will never lead us to any other information. So, even if there is a presence of liquid water on Europa, which we do not necessarily know since the argument says "strongly suggest," that doesn't mean there MUST be some type of life on Europa. It could be possible that many other things are also necessary for life on Europa to exist and the presence of liquid water is merely ONE of the requirements.

Thus, answer choice (B) is correct: "fails to address adequately the possibility that there are conditions necessary for the evolution of life in addition to the presence of liquid water."

Hope that clears things up! Please let us know if you have any other questions.

alymathieu on January 21, 2019

Can you explain why a is wrong

MichelleRod on January 22, 2019

Thanks for your question @alymathieu

The author is only suggesting that there likely is life where there is water. A is wrong because the author never argues that there cannot be life where there is no water. In other words, the author never says or suggests that life "could not have evolved anywhere that this condition does not hold."