Self-study
Council member: The profits of downtown businesses will increase if more consumers live in the downtown area, and a decrease in the cost of living in the downtown area will guarantee that the number of consumers living there will increase. ████████ ███ ███████ ██ ████████ ██████████ ████ ███ ████████ ██████ ████████ ███████ ██████████ ██████████
Summary
The stimulus can be diagrammed as follows:
Notable Valid Inferences
If cost of living in the downtown area decreases, the profits of downtown businesses will increase.
If cost of living in the downtown area decreases, traffic congestion will decrease.
If more consumers live in the downtown area, traffic congestion will decrease.
20.
If all the council member's ██████████ ███ █████ █████ ███ ██ ███ █████████ ████ ██ █████
a
If downtown traffic ██████████ ██████████ ███ ██████ ██ █████████ ██████ ██ ███ ████████ ████ ████ █████████
Could be false. “Congestion decrease” is not a sufficient condition for “consumers increase”, so there’s no reason to believe that a congestion decrease would cause an increase in the number of consumers in the area. Maybe people like sitting in traffic!
b
If the cost ██ ██████ ██ ███ ████████ ████ ██████████ ███ ███████ ██ ████████ ██████████ ████ █████████
Must be true. As shown below, by chaining the conditional claims, we see that “cost of living decreases” is a sufficient condition of “profits increase.”
c
If downtown traffic ██████████ ██████████ ███ ████ ██ ██████ ██ ███ ████████ ████ ████ █████████
Could be false. “Congestion decrease” is not a sufficient condition for “cost of living increase”, so there’s no reason to believe that a congestion decrease would cause an increase in the cost of living in the area.
d
If downtown traffic ██████████ ██████████ ███ ████ ██ ██████ ██ ███ ████████ ████ ████ █████████
Could be false. “Congestion decrease” is not a sufficient condition for “cost of living decrease”, so there’s no reason to believe that a congestion decrease would cause a decrease in the cost of living in the area.
e
If the profits ██ ████████ ██████████ █████████ ███ ██████ ██ █████████ ██████ ██ ███ ████████ ████ ████ █████████
Could be false. “Profits increase” is not a sufficient condition for “more consumers”, so there’s no reason to believe that a profit increase would cause an increase in the number of consumers living in the area.