First Date: Based on the presence of warmth-adapted open-ground beetles replacing cold-adapted arctic beetles in sediment samples.
Second Date: Based on the emergence of spruce forests as indicated by pollen grains found in the same sediment samples.
The first date (beetles) is over 500 years earlier than the second date (spruce forests).
A
Toward the end of the ice age, warmth-adapted open-ground beetles ceased to inhabit areas where the predominant tree cover consisted of spruce forests.
B
Among those sediments deposited toward the end of the ice age, those found to contain cold-adapted arctic beetle fragments can also be expected to contain spruce-pollen grains.
C
Ice masses continued to advance through North America for several hundred years after the end of the ice age.
D
The species of cold-adapted arctic beetle that inhabited areas covered by ice masses died out toward the end of the last ice age.
E
Toward the end of the ice age, warmth-adapted open-ground beetles colonized the new terrain opened to them faster than soil changes and seed dispersion established new spruce forests.
Essayist: Common sense, which is always progressing, is nothing but a collection of theories that have been tested over time and found useful. When alternative theories that prove even more useful are developed, they gradually take the place of theories already embodied in common sense. This causes common sense to progress, but, because it absorbs new theories slowly, it always contains some obsolete theories.
Summary
Common sense is always progressing.
Common sense is a collection of theories that have been tensed and found useful over time.
Alternative theories that are even more useful gradually replace the theories that are common sense.
This replacement happens slowly, so common sense always contains some obsolete theories.
Notable Valid Inferences
In common sense, there are always at least some theories that have more useful alternatives.
A
At least some new theories that have not yet been found to be more useful than any theory currently part of common sense will never be absorbed into the body of common sense.
This could be false. The stimulus discusses theories that are already developed and proven to be more useful. Further, the stimulus doesn’t discuss which theories will never be absorbed into common sense.
B
Of the useful theories within the body of common sense, the older ones are generally less useful than the newer ones.
This could be false. The stimulus does not give any relationship between age of theory and usefulness.
C
The frequency with which new theories are generated prevents their rapid absorption into the body of common sense.
This could be false. The stimulus just says that common sense absorbs new theories slowly; we don’t know the reason for this slow progress.
D
Each theory within the body of common sense is eventually replaced with a new theory that is more useful.
This could be false. We know that some theories are eventually replaced; we don’t know that each theory will be replaced.
E
At least some theories that have been tested over time and found useful are less useful than some other theories that have not been fully absorbed into the body of common sense.
This must be true. Progress is slow, so it takes time for alternative theories that have been proven to be more useful to be absorbed into common sense. Until these alternatives are absorbed into common sense, the theories in common sense are less useful than the alternatives.
Because if an entity doesn’t have a corresponding right not to be cut down, then there is no obligation to that entity. And we know trees aren’t the kind of thing have have rights.
The flaw in the argument is that we might have an obligation to entities besides trees not to cut trees down. For example, maybe we’re obligated to our future children not to cut down trees.
The author must assume that we do not owe an obligation to other entities not to cut down trees.