Researcher: Research has shown that inhaling the scent of lavender has measurable physiological effects tending to re...

SamA on September 23, 2019

Hello @megmcdermott,

Premise: Inhaling the scent of lavender has psychological effects tending to reduce stress.

Premise: Intense stress can impair the immune system, making one more susceptible to illness.

Conclusion: It is likely that people who inhale lavender reduce their incidence of illness by doing so.

What assumption does the argument require? In other words, what is unstated in the premise, but without it the argument falls apart?

A key word here is "intense." We do not know how mild or moderate stress affect the immune system. Therefore, we cannot make a claim about lavender and illness that does not involve intense stress levels. The correct answer should have something to do with stress.

Let's go through the answer choices.

A. Incorrect. We do not care about how other scents reduce illness. We are talking specifically about lavender.

B. This is correct, because the argument depends on this assumption. If someone does not have enough stress to impair the immune system, then lavender won't make a difference. We need B to be true in order for the argument to make sense. If it is true, then some people who inhale lavender would be more likely to get sick if they didn't, which supports our conclusion. "Under enough stress" to impair the immune system meets our requirement of "intense stress."

C. Incorrect. We don't need to know how lavender smellers compare to non-lavender smellers. The researcher only makes a claim about regular lavender smellers, and no one else.

D. Stress reduction doesn't need to be the primary mechanism by which lavender reduces susceptibility to illness. The author never claims this has to be the case. Stress reduction could be the secondary mechanism and the argument still works.

E. We do not need this to be true. There could be other ways in which reduced stress reduces susceptibility of illness even if the immune system is unimpaired.