Because few arguments are presented with perfect clarity, the first step in a logical assessment of an argument must be to prepare the material for proper evaluation. The entire process of analyzing an argument critically--for its inherent rational appeal rather than for its style or for fallacious (deceptive) elements--can be approached in many ways. The following six-step plan offers a useful way of breaking the process into stages:
1. Locate the conclusion:
Many arguments are constructed after their conclusions have been determined. Starting with the conclusion may not only reveal special assumptions, but the actual motive behind the argument.
An argument's conclusion is what the person making the argument is ultimately trying to convince you of, i.e., the person's point. To try to identify the conclusion of an argument ask yourself 'what does the person making the argument want me to walk away thinking?' (Note if the answer is 'nothing', them you're not dealing with an argument.)
Some Conclusion Indicator Words: therefore, consequently, as a result, thus, it follows that, so
2. Analyzing the premises
Identifying the Premises: To try to identify the
premises of an argument ask yourself 'what reasons is the person giving me to
accept his point?'
Some Premise Indicator Words: since, because, given that
Missing Premises and Conclusions: When trying to figure out what the premises and conclusion of an argument are, we need to ask ourselves what the person's point is. But remember that people don't always come out and say what their point is. Similarly people may not always explicitly mention all the premises they are working with. As a result, we must be prepared to identify both missing premises and missing conclusions (i.e., conclusions or premises that are not explicitly stated by the arguer, but that are implicit in what the arguer does say).
How are we supposed to tell what the arguer has in mind if he or she doesn't say it? By assuming person making the argument is rational and reasonable, e.g., that she holds the position she does because she thinks she has good reason to believe it. If an argument seems incomplete, we must ask ourselves what assumptions it is reasonable to think the person must be relying on. That is, what must this person believe in order to think she has made a coherent argument?
Consider the following argument:
I've never had any problems with the last four Fords I've owned, so my new Ford should be reliable.
Obviously that breaks up into
P1: I've never had any problems
with the last four Fords I've owned
C: My new Ford should be reliable
3. Clarify the language:
Ambiguities make logical argument impossible. Identify the key definitions upon which the argument rests and recast any uncertain language.
4. Eliminate the excess:
Remove anything which may distract from the actual argument; eliminate any prejudicial language in favour of a neutral wording. Remove clutter, such as universally-accepted definitions or assumptions (be careful of these).
5. Classify statements:
Statements can be either statements of fact (something
known to be true) or statements of opinion (personal view); distinguish between
the two.