Self-study
The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. ██ █████ █████ ███ ██ █████ ████████ ███████ █████ ███ ███ █████ ██████ ███ ██ ███ ████ ██████████ ███ █ ██████ ████ ██████ █████████ ███ ██ ███ █████ █████ ██ ███ ████ ██████████ ██ ██████ █████ ███ █████ ██ ███████████ ███ █████ ██████ ███████████ ███ █████ ██████ ███ ████ ███ ████ ███ ████ ██ ███ ████ █████████ ████ ███████
Summary
The argument concludes that the dwarf masked owl will reside on the Baja peninsula this winter only if steps are taken to bring back spiny cacti. This is supported by the claims that spiny cacti provide the only suitable nesting sites for this owl on the Baja peninsula, and that a recent blight destroyed all of the peninsula’s spiny cacti.
Notable Assumptions
The conclusion that taking steps to reestablish spiny cacti is necessary for the owls to reside on the Baja peninsula over the winter involves several assumptions:
- That spiny cacti will not reestablish themselves on the Baja peninsula before winter even if no steps are taken.
- That there are no other plants which could be introduced to substitute for spiny cacti.
- That suitable nesting sites are necessary for the owls to reside on the Baja peninsula over the winter.
25.
The argument depends on assuming █████ ███ ██ ███ ██████████
a
No birds of ████ █████ ████ ███ █████ ██████ ███ ████ ██ ███ █████ ███████
The impact of the cactus blight on other birds is irrelevant to this argument, which is purely about the impact on the dwarf masked owl.
b
If the Baja █████████ ████████ █████ ██████ ████ ███ █████ ██████ ███ █████ ███ ██████ ████ ██████
Posing spiny cacti as a sufficient condition for the owl to reside on the peninsula over winter doesn’t contribute to the conclusion that reestablishing cacti is a necessary condition. Like (D), this is unnecessary.
c
On occasion the █████ ██████ ███ ███ ████ █████ ██ ████ ███ ██████ ████ ███ ████ ███ ██████ █████████ ██████
Whether this owl has previously spent the winter elsewhere doesn’t affect whether reestablishing the spiny cactus is necessary for the owl to spend this winter on the peninsula.
d
The dwarf masked ███ ████ ███ ████ ███ ██████ ████ ██ ███ ████ █████████ ████ ██ ████ ██████ ████████ ██ █████ ██████
Like (B), this makes spiny cacti a sufficient condition for the owl to spend winter on the peninsula. This isn’t necessary for the argument, which poses reestablishing the cacti as a necessary condition.
e
Suitable nesting sites ████ ██ ███████ █████ ███ █████ ██████ ███ █████ ███ ██████ █████
The argument concludes that reestablishing spiny cacti is necessary on the basis that they exclusively provide nesting sites for the owl. Without this assumption, that link of support would be broken and the conclusion would be unsupported.