Self-study
Support Monarch butterflies must contend with single-celled parasites that can cause deformities that interfere with their flight. ██ ███████████ ██ ███████ ███████████ ████ ████ ███ █████████ ██ ████ ██ ██ ███████ ███ ███████ ████████ ██ ███ ██████████ █████ ████ ████ ██ ███████ ██ █████ ██ █████████ ███████████ ███ █████████ ████ █████ ████ █████████ ██████ ███████ ███████████ ██ █████ █████ ██████████
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that migration allows monarchs to avoid the parasites. She supports this by saying that up to 95% of non-migrating monarch populations are infected, while less than 15% of migrating populations are infected. She also says the parasites can interfere with monarchs’ flight.
Identify and Describe Flaw
This is the cookie-cutter flaw of assuming that correlation proves causation. The author notes a correlation between migration and lower infection percentages and then concludes that migration causes monarchs to avoid infection. Her reasoning is flawed because she overlooks two key alternative hypotheses:
(1) The causal relationship could be reversed—maybe parasitic infections prevent monarchs from migrating, not the other way around.
(2) Another factor might cause certain populations to not migrate and to be more vulnerable to parasites.
8.
The reasoning in the argument ██ ██████ ██ ████ ███ ████████ █████████ ███ ███████████ ████
a
monarch butterflies are ██████ ██ ██████ █████ █████ ███ ████ ████ █████████
Migrating monarchs have a lower percentage of infections, but it doesn’t matter whether they can detect which areas are free from parasites. Even if the author did address this, it wouldn’t impact her conclusion that migration allows these monarchs to avoid parasites.
b
long migrations are ██ ██████ ██████████ ████ █████████ ████ ███ █████ ██████████
The author just concludes that migration allows monarchs to avoid the parasites; she never claims that long migrations are better than short ones. Even if long and short migrations are equally effective, this wouldn’t impact her conclusion.
c
populations of monarch ███████████ ████ ████ ███ ████████ ███ ████ ██████ ████ █████████ ███████████
The author addresses the percentage of monarchs infected, not the number. Even if there are more non-migrating monarchs, it doesn't change the fact that they have a higher percentage of infections. The question of what causes this higher percentage still remains.
d
monarch butterflies infected ████ █████████ ███ █████████ ██████ ██ ███████
The author overlooks the possibility that the causal relationship is reversed. Maybe the parasites cause monarchs not to migrate, rather than the other way around. After all, the author does say that the parasites can interfere with the monarchs’ flight.
e
populations of monarch ███████████ ████ ███ ██ ███████ ██ ████ ████ ██████ ████ ███████
Even if monarchs with stable food sources tend not to migrate, this doesn’t change the fact that these non-migrating populations have a higher percentage of infections. It also doesn’t affect the conclusion that migration helps the migrating monarchs to avoid the parasites.