Question

consider the following proposition and, based on the quote, answer questions a through c.
\if you want to understand how life began, it makes sense to begin by looking for features that are shared by existing forms of life\ --sean carrol, the big picture

a. look for extinct life forms that share no features with existing life forms.
b. look for existing life forms in the same region of the planet.
c. look for features that are shared by existing life forms.
d. look for features that are not shared by existing life forms.

b. if you look for features shared by existing forms of life, does that mean you want to understand the origins of life?
a. yes, to understand the origins of life, you must look for shared features of existing forms of life.
b. no, you may be looking for shared features for a different reason.
c. no, looking for shared features means you are looking for something besides the origins of life.
d. yes, it can be concluded that looking for shared features means you want to understand the origins of life.

c. if you dont look for features shared by existing forms of life, what can you conclude?
a. all existing forms of life share features.
b. you do not want to understand the origins of life.
c. you want to understand the origins of life.
d. existing forms of life do not share features.

Explanation:

Part a

The quote says to understand life's beginning, look for shared features in existing life. Option A looks for extinct life with no shared features (opposite). Option B focuses on same - region existing life, not shared features. Option C matches the quote's advice. Option D looks for unshared features (opposite).

Just because someone looks for shared features in existing life doesn't necessarily mean their goal is to understand life's origins. There could be other reasons (e.g., studying evolution in a different context, classifying organisms). Option A says it's a must, which is too absolute. Option C says it's for something besides origins, but it could still be for origins or other things. Option D says it can be concluded, but we can't be that certain. Option B correctly notes that there could be a different reason.

The original proposition is a conditional: if you want to understand life's beginning, look for shared features. The contrapositive isn't "if not looking for shared features, then don't want to understand origins" in a strict logical sense, but from the options, Option A is about whether all existing life shares features (not related to the conditional). Option C is the opposite of what the conditional implies. Option D is about whether existing life shares features (not about the goal). Option B follows the idea that if the action (looking for shared features) related to the goal (understanding life's origin) isn't taken, it's likely the goal isn't present.

Answer:

C. Look for features that are shared by existing life forms.

Part b