So far in this series on reading comprehension, we have looked at literal comprehension, inferences, and deductive thinking. In this final segment, we turn our attention to logical reasoning. In more advanced courses, students are asked to determine whether the position taken by the writer is logically reasonable. They have to decide whether or not the statements made in the author's presentation contain a logical fallacy. In order to determine the logical solidarity of a position or argument, the student needs to be able to test the author's case against the known rules for any valid argument. That assumes that the student knows the various rules of argument, can understand these rules and can systematically apply them to the stated position of any author.
Rules of Argument
There are six specific rules for determining whether or not an argument is valid. Sigfried Engelmann first made these rules explicit in his early work on reading comprehension. Many times students are expected to find the flaw in a presentation without being specifically aware of the six tests which the presentation must be able to pass. Students are more likely to be successful in determining the validity of an argument if they can use specifically stated rules as tests of the author's position. To assist them, the six rules of argument are specified below with examples in which the rule is broken.
Rule #1: Just because two things happen at the same time this does not mean that one thing causes the other.
Example: Every time I sit down to read my book, the phone rings. My mother has not called me all week. I am going to read my book so that she will call today.
The student has to determine whether the conclusion the author wants you to reach violates this argument by drawing a conclusion based on proximity of two events in time. The student has to reject the conclusion because the rule tells them that there is no causal connection between the events.
Rule #2: Just because you know about a part this does not mean that you know about the whole thing.
Example: The headlights on my car are not working. We can't go anywhere now because the car probably won't start.
In order to apply this rule the student needs to be able to discriminate between wholes and parts. They then can determine that just because one part does not function, it does not mean that other parts, or the entire entity will not.
Rule #3: Just because you know about the whole thing this does not mean that you know about every part.
Example: Dogs have a good sense of smell and great vision, so they must have great hearing as well.
Again the student has to differentiate between the parts and the whole and know the limits to which an argument applies. The argument cannot be extended to aspects that are not specifically stated. The student has to discern that we have no information about this particular part of the organism and therefore cannot apply the same conclusion as we did for those parts for which we do have information.
Rule #4: Just because the words are the same, this does not mean that they have the same meaning.
Example: The farmer was so poor that even his ducks had bills.
The student has to know that there is more than one meaning for the term "bill."
There are many words which have more than one meaning. Using such words could lead to the student choosing a meaning that was not intended and then draw a faulty conclusion.
Rule #5: Just because the information presents some choices, this does not mean that there are no other choices.
Example: When the price of oil goes up, we have to raise the price we charge for gas immediately.
The student has to be aware that other choices have not been presented. The price increase might not have to occur until the gas station buys a new shipment of the more expensive gasoline. In this case, the author is limiting the choices to those which favor his position. The student has to determine what other possibilities exist that explain the conclusion so as to weigh the argument in light of all of the possible choices.
Rule #6: Just because an event happened in the past this does not mean that it will or will not happen again.
Example: The restaurant that was here before went bankrupt. I guess this new one will probably go bankrupt too.
The student has to know that there are factors other than history that will affect the outcome for this event. This is similar to the first rule about the effect of time on events. There is no causal or predictive connection between time and the event which is being presented.
Using the Rules
Once students learn the rules about valid argument they can be much more insightful in formulating the conclusions that they draw. Students can apply these lessons to everyday experience. When they see an advertisement that presents a beautiful woman or a handsome man as part of the copy with some product, they can spot the flaw that says that just because two things occur at the same time the one does not cause the other. They can then conclude that just because you buy this product, you will not necessarily attract beautiful people or be perceived as more attractive.
Students can apply the rules for argument in a variety of situations. At any time when they are editing information, writing a position paper or responding to someone else's, the rules will assist them to spot logical flaws, overgeneralizations and omissions. The rules can be used in teaching oral debating or other forms of interactive public speaking.