The Structure of Argument (4)

The Structure of Argument (4)• How to identify premises and conclusions in argument• How to identify ambiguous argument structure & hidden

assumptions• How to write a summary• How to distinguish between an argument and an explanation

Identifying Hidden AssumptionsMany real-life arguments come to us incomplete, depending on hidden assumptions—unstated premises and conclusions.

Identifying Hidden AssumptionsKen is lazy, and lazy people don’t last long around here.

Identifying Hidden AssumptionsKen is lazy, and lazy people don’t last long around here.

[Missing conclusion: Ken won’t last long around here.]

Identifying Hidden AssumptionsSince I’ve sworn to put up with my tired Honda until I can afford a BMW, I must resign myself to the old wreck for a while longer.

Identifying Hidden AssumptionsSince I’ve sworn to put up with my tired Honda until I can afford a BMW, I must resign myself to the old wreck for a while longer.

[Missing premise: I can’t afford a BMW now.]

Identifying Hidden AssumptionsThe senator is a Republican, so he is opposed to gun control.

Identifying Hidden AssumptionsThe senator is a Republican, so he is opposed to gun control.

[Missing premise: Republicans are opposed to gun control.]

Identifying Hidden AssumptionsIn everyday speech and text, filling in the omitted assumptions would seem insulting to our intelligence.

Literature, however, depends upon the reader’s ability to make plausible assumptions.

Identifying Hidden AssumptionsYon Cassius has a lean and hungry look; such men are dangerous.

—Shakespeare, Julius Caesar

Identifying Hidden AssumptionsWe are born in debt, owing the world a death.

—David J. Morris, “In Terror’s Shadow”

Identifying Hidden AssumptionsAt the heart of critical thinking lies the ability to read between the lines—to discern between the implicit and the explicit.

Argument lies in-between as well.

Identifying Hidden AssumptionsJohn is Lisa’s father, so clearly he is obligated to support her.

Identifying Hidden AssumptionsThe noise lay everywhere they ran, stratified sound collecting around them, and he walked away from it and into it at the same time. (4)

—Don DeLillo, Falling Man

Identifying Hidden AssumptionsHe is thinking again, looking past the face in the mirror, which is not his, and waiting for the day to come, clear skies, light winds, when there is nothing left to think about. (178)

—Don DeLillo, Falling Man

Identifying Hidden AssumptionsShe seemed to be blaming him for this, the fact of leaving, the fact of marrying, the thoughtless gesture of reuniting, and at the same time did not seem to be talking to him at all. (91)

—Don DeLillo, Falling Man