Self-study
Biologist: We know the following things about plant X. █████████ ████ █████ █████ ██████ ████ ████ █████ ███ █████ ████ █████ ████████ █████████ ████ ██████ ██████ ██████ ████ █████ ████████ ███ █████████ ████ ██████ ████████ ██████ ████ ██████ ███████ █ ████████ ██ █████ █ ██ ██ ██████ ███ █ ████ ████ ███ ██████ ███████
Summary
Specimens with fuzzy seeds have long stems.
Specimens with fuzzy seeds lack white flowers.
Specimens with curled leaves have white flowers.
Specimens with thorny seedpods have curled leaves.
The biologist’s plant has a long stem and curled leaves.
Very Strongly Supported Conclusions
The biologist’s specimen has white flowers.
The biologist’s specimen lacks fuzzy seeds.
24.
From the biologist's statements, which ███ ██ ███ █████████ ███ ██ ████████ ████████ █████ ███ ████████ ██ █████ █ ██ ███ ███████████ ███████
a
It has white ███████ ███ ██████ █████████
Unsupported. We know the specimen has white flowers, but we don’t know if it has thorny seedpods. Careful with negations—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but that doesn’t mean “curled leaves” is a sufficient condition for “thorny seedpods”!
b
It has white ███████ ███ █████ ██████ █████████
Unsupported. We know the specimen has white flowers, but we don’t know if it has thorny seedpods. Careful with negations—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but “curled leaves” tells us nothing about whether a specimen has thorny seedpods!
c
It has white ███████ ███ █████ █████ ██████
Very strongly supported. As shown below, by chaining the conditional claims, we see that “no curled leaves” is a necessary condition of both “fuzzy seeds” and “no white flowers”. Having curled leaves, then, is a sufficient condition for “white flowers” and “no fuzzy seeds”!
d
It has fuzzy █████ ███ ██████ █████████
Anti-supported. Because the specimen has curled leaves, we know that it doesn’t have fuzzy seeds. We can’t determine whether it has thorny seedpods—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but “curled leaves” tells us nothing about thorny seedpods!
e
It lacks both █████ ███████ ███ █████ ██████
Anti-supported. Because the specimen has curled leaves, we know that it has white flowers. It is true that it doesn’t have fuzzy seeds.