PHIL 2003 Study Guide - Final Guide: Brain Death, The Toasters, Law School Admission Test
15 Sep 2019
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Simple and complex arguments
Arrow diagrams
Deductive and nondeductive arguments
Having looked at the elements of arguments, we’ll now consider the structures of
arguments.
The structure of an argument (which corresponds to the structure of the
reason for belief the argument expresses) is ______________________________
_________________________________________________________________
_________________________________________________________________.
One aspect of an argument’s structure concerns whether the premises are intended
to be taken together, or by contrast separately, in support of the conclusion. Thus,
compare the following two arguments:
If the 17th century French philosopher René Descartes was correct, the mind and
the brain are two distinct entities. If the mind and the brain are two distinct
entities, life after brain death is possible. So if Descartes was correct, life after
brain death is possible.
You really ought to switch to a vegetarian diet. For one thing, it’s better for the
environment. For another, it's more laudable morally. Also, it’s better for your
health.
In the first of these arguments, the two premises seem pretty clearly intended to be
taken together in support of the conclusion: neither one on its own would
presumably provide any support for the conclusion.
In the second argument, however, it seems that each of the three premises is meant
to be taken separately in support of the conclusion: each one on its own
presumably provides some support for the conclusion.
Another aspect of an argument’s structure has to do with whether the
argument contains any lemmas. A lemma is ________________________
_________________________________________________________________
_________________________________________________________________.
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To illustrate, compare the following two arguments:
Sometimes, pursuing a meaningful life can involve acting in morally dubious
ways. If that’s true, however, then morality isn’t the only ultimate value. Thus,
morality isn’t the only ultimate value.
98% of everyone who quits their antidepressant medication cold-turkey
experiences “brain zaps.” Thus, if you quit your antidepressants cold-turkey, it’s
likely that you’ll experience brain zaps. It follows that you don’t want to quit your
antidepressants cold-turkey, since you don’t want to put yourself in a situation
where it’s very likely that you’ll experience brain zaps.
In the second argument, unlike in the first, there is a lemma (viz., the proposition
that if you quit your antidepressants cold turkey, it’s likely that you’ll experience
brain zaps).
A simple argument is _____________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________.
Simple arguments, as we’ll see, can have one, two, or more premises.
A complex argument, by contrast, is _________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________.
We can represent this structural difference between arguments by making use of
arrow diagrams. In an arrow diagram, the node that stands at the very bottom
represents the main conclusion of the argument. The nodes that appear above this
bottom node represent premises (including lemmas).
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When nodes are joined by a horizontal line in an arrow diagram, they represent
premises that are intended to be taken together in support of the conclusion.
Simple arguments are represented by simple arrow diagrams. These are
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________.
Here are some examples of simple arrow diagrams:
Complex arguments are represented by complex arrow diagrams. These arrow
diagrams may include intermediate nodes, and above-the-arrow nodes not joined
by a horizontal line (which means that those above-the-arrow-nodes represent
premises intended to be taken separately in support of a conclusion).
Here are some examples of complex arrow diagrams:
Document Summary
Having looked at the elements of arguments, we"ll now consider the structures of arguments. The structure of an argument (which corresponds to the structure of the reason for belief the argument expresses) is ______________________________ One aspect of an argument"s structure concerns whether the premises are intended to be taken together, or by contrast separately, in support of the conclusion. You really ought to switch to a vegetarian diet. For one thing, it"s better for the environment. In the first of these arguments, the two premises seem pretty clearly intended to be taken together in support of the conclusion: neither one on its own would presumably provide any support for the conclusion. In the second argument, however, it seems that each of the three premises is meant to be taken separately in support of the conclusion: each one on its own presumably provides some support for the conclusion.
