Stage 2:
Evaluate the Line of Reasoning
The main aspects of critically evaluating a line of reasoning are:
- Do the reasons progress logically?
- Are the reasons relevant, contributing and plausible?
- Is there any flawed reasoning?
If you apply each of these questions to a piece of writing you can quickly see if there are indeed any holes in the argument.
Logical Progression
This is important when it comes to the strength of an argument. If one reason does not clearly lead to another reason, or if there are gaps in the lines of reasoning then this makes an argument weaker.
In our example:
Medical evidence suggests that outdoor play for children is desirable (A). Parent’s attitudes reflect this (B). Lack of facilities would prevent outdoor play (C). Parents believe more outdoor play areas are needed (D).
A B
B + C D
However if the argument was:
Medical evidence suggests that outdoor play for children is desirable (A). Lack of facilities would prevent outdoor play (C). Parents believe more outdoor play areas are needed (D).
A + C D
The argument becomes weaker. As the conclusion is that Parents want more outdoor play areas, however the reasons only mention medical evidence. It does not identify a link between Medical evidence and what Parents believe. Although this example it is common sense that parents would support medical evidence, however it identifies clearly how assumptions can be made in arguments. These assumptions are not necessarily true, and therefore are potential weaknesses.
Irrelevant/Plausible Reasoning
This is one of the most obvious flaws in an argument, when one reason for a situation simply is unrealistic or entirely impossible to prove.
Example: Medical evidence suggests that outdoor play for children is desirable (A). Parent’s attitudes reflect this (B). Ancient civilisations collapsed due to lack of outdoor play areas (E). Lack of facilities would prevent outdoor play (C). Parents believe more outdoor play areas are needed (D).
Here it is obvious that reason E is ridiculous. It does not disprove the conclusion, but it does call into question the authors credibility.
This example was exaggerated, in a much more long winded argument such an academic journal this reason might not stand out quite so obviously. Therefore it is important when reading to avoid ‘glossing over’ reasons, identifying they are there but not considering what they are actually saying.
Flawed Reasoning
This is similar to Implausible reasoning, however is often less obvious. The main aspects are:
- Casual connections – two events occurring at the same time can be linked in an argument, when there is no actual connection. EG – I failed my test on a Tuesday, Tuesdays are a bad day to take tests.
- Generalisations – Using case studies or specific examples and generalising to the overall population.
- Inappropriate Comparisons – Using examples that are so unrelated to each other they cannot be compared. For example comparing how much food a gorilla needs to survive against that of an ant. Both are animals yet clearly totally unrelated.