Critiquing an Argument:
the Quick'n'Dirty Syllogistic Method

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An Argument consists of statements, called premises (or reasons) , believed to support a deduction, a statement also called a conclusion. (There are often additional logically irrelevant statements mixed into the argument to make it more persuasive.)

A Critique examines the logical construction of an argument. It also identifies the what the argument presupposes in terms of facts, definitions or preliminary deductions. It attacks these presuppositions in ways to be discussed below.

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Step 1: From your argument, construct a preliminary dummy syllogism that has the conclusion to be examined. This is done as follows:
Suppose the argument to be examined is Because it reduces the money supply, higher taxes lower economic growth.

The conclusion is higher taxes lower economic growth.; a premise is it reduces the money supply. ("Because" is a word that identifies premises)

a. Divide the conclusion statement into subject and predicate,

 subject predicate Higher taxes lower economic growth
b. Put in a dummy variable X so as to make two premises:
 premise Higher taxes X premise X lowers economic growth
c. See if additional premises provide some information for identifying X. From our example we get it ( i.e. higher taxes) reduces the money supply. We plug this in the chart for X, adjust the English, and add the conclusion at the bottom.
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 Dummy Argument premise Higher taxes reduce money supply premise Reduced money supply lowers economic growth conclusion Higher Taxes lower economic growth

Step 1B: Treat the premises as the conclusions to a preliminary argument and analyze them as shown above, constructing additional dummy arguments, if necessary.

IF AT THIS POINT YOU HAVE RUN OUT OF ADDITIONAL PREMISES TO USE, GO ON TO STEPS 2 AND 3.

Using steps 2 and 3 below, go back through the original argument to see if there is anything which could fill in for the X's in your new dummy arguments. .

Step 2: Identify evaluative statements; they presuppose facts.

1. Statements are evaluative or not-evaluative

Evaluative statements begin (or end) with such phrases as

1. It is important to remember that...OR X is important.

2. It is good that ...

3. That ... is not worth considering.

Examples:
a. It is important to remember that Sam is a felon.

b. It is good that taxes have been lowered.

c. That John has been accused of theft is not worth considering.

Presuppositions: Evaluative statements presuppose the truth of that which they evaluate:
Example a. presupposes that it is true that Sam is a felon.

Example b. presupposes that taxes have been lowered.

Example c. presupposes that John has been accused of theft.

Any statement that is not evaluative is not-evaluative. For the purposes of analyzing your original argument, disregard the evaluative statements.

Other Important Points:
1. The presupposed "facts" may be wrong.

2. Evaluations require additional argument, even if we accept the facts they presuppose. As premises, they are only as strong as our willingness to accept them at face value. So, we may accept as fact that Sam is a felon, and still consider it unimportant. Step 3 . Go back through the argument. Sort out non-evaluative statements into three kinds: perceptions (P), reports (R) or deductions (D). (Note: the same statement may fit into more than one category.) Most statements in arguments are reports. They may be reports of perceptions, reports of reports, or reports of deductions. Perception Statements are generally given in the present tense, i.e. statements like

A. I hear a loud sound.

B. John is saying nothing.

Presuppositions of Perception Statements: Perception statements presuppose the normal functioning of the faculties of the perceiver and the normality of the situation in which the perception was made.

If, for example, we know that John is drunk, or that the lighting is bad, we might reject the claim by John, "I see a pink elephant" as indicating the presence of an elephant, or the color of an elephant.

However, perception statements are rarely found in argument. Rather reports of them are given as premises. Report Statements can be of perceptions, other reports, or deductions.

Report of A.: I heard a loud sound.

Report of B.: John was saying nothing.

Reports can be citations from books, or quotations as well, e.g.

1. "The Oxford English Dictionary defines "crime" as..."

2. The New York Times reported that Stevenson died yesterday.

3. John told me he was on his way home.

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Presuppositions of Reports: Reports statements presuppose accuracy of quotation or citation, i.e. that the reporters haven't misheard, misread or misstated what they report on.

They also presuppose that the medium of transmittal has been stable and not subverted, that the ink, telephone line, computer program, etc. has not misfunctioned or been tampered with. Deduction Statements are arrived at by reasoning from other statements, which may themselves be perceptions, reports or deductions. Indicators that a statement is a deduction is the presence of words or phrases like, so, therefore, because of this, consequently, as a result, etc. For example.

John is sick; so, he won't finish his paper on time.

A conclusion has been drawn: i.e.

John won't finish his paper on time

A premise is given: i.e.

John is sick.

The deductive statement that is the focus of the argument is generally called its conclusion, although there may be many subsidiary deductions (in mathematics, called lemmas) along the way.

Presuppositions of Deductions: Deductions statements presuppose that no errors in deduction have been made, nor that any factually false premises have been introduced into the argument.

If you can construct and fill in dummy syllogisms with premises found in the text of the argument you are analyzing, you can be sure the argument is valid, i.e. well formed. You must use other sources to determine the factuality of the premises however. (See Facts and Authority)

Flowchart of Process