Self-study
Nylon industry spokesperson: Even though cotton and nylon are used for similar purposes, some people have the mistaken notion that cotton is natural but nylon is not. ████████ ███████ ████ ██████████ ████ ████ █████████ ███ ████ ███ ████████ ██ ███ ███████████ ███████ ███ ██████████ ██ ████████ ███ █████████ █████ ████ ████ █████ ██ ████ █████ ████ ███████ ██████████ ███████ ███████
Summary
The spokesperson’s argument leads to the implicit conclusion that nylon, like cotton, is natural. How can this be? Because nylon’s main components have natural sources at their origin: nitrogen comes from the atmosphere, and petroleum comes from oil which comes from ancient plants.
Notable Assumptions
The spokesperson assumes that, if a product’s main components originally come from natural sources, then the product is natural. That’s the only connection the original sources of nitrogen and petroleum have with nylon being natural.
So, we need to find a principle that affirms this assumption, and tells us that if the main components can be traced back to natural sources, that is sufficient for the resulting product to be natural.
3.
Which one of the following ███████████ ██ ██████ ████ █████ ██ ███████ ███ █████ ████████ ██████████████ ██████████
a
A substance is █████████ ████ ██ ███ ████████ ██ ██████ ██ ██████████
The function a product serves being natural plays no part in the argument, so this cannot bridge between the spokesperson’s premises and conclusion.
b
A substance is ██ ████ ███████ ████ ███ █████████ ████ ██ ███ ███████████
The spokesperson never mentions the processes used in producing nylon, so this can’t help us. Also, like (C), this rule poses a necessary condition for a product to be natural, and we’re looking for a sufficient condition.
c
A substance is ██ ████ ███████ ████ ███ █████ ███████ ██████████
Like (B), this rule creates a necessary condition for a substance to be natural: that its components are natural. That’s the inverse of what we’re looking for, and can’t bridge to the conclusion that nylon is natural.
d
One substance can ██ ████ ███████ ████ ███████ ██ ████ ███ ██ ██████ ███████ ████ ███████ ███████████
This is just irrelevant. Neither the idea of one substance being more natural than another, nor the idea of something having completely natural sources, figures in the argument at all.
e
A substance is ███████ ██ ███ ███████ ██ ███ ████ ██████████ ███ ████████
So if nylon’s main components (nitrogen and petroleum) have natural origins, then nylon is natural. This exactly fills in the argument’s assumption, and bridges the gap from the spokesperson’s premises to the conclusion that nylon is natural.