The post hoc fallacy and the non sequitur fallacy are sometimes conflated, but they are fundamentally different.
- Non sequitur is Latin for “does not follow.” A non sequitur is an invalid deductive argument whose conclusion doesn’t follow logically from its premises because of its faulty structure. Any formal fallacy that doesn’t fall into another, more specific category can be called a non sequitur fallacy.
- Post hoc ergo propter hoc is Latin for “after this, therefore because of this” and refers to an informal fallacy in which causation is assumed based on the chronological order of events. It is also called “post hoc fallacy.”
Continue reading: What is the difference between the post hoc fallacy and the non sequitur fallacy?
Post hoc and hasty generalization fallacies both involve jumping to conclusions, but there is a difference between the two.
The post hoc fallacy could be considered a subcategory of the hasty generalization fallacy that focuses specifically on causation and timing.
Continue reading: What is the difference between post hoc fallacies and hasty generalization fallacies?
Post hoc fallacies can be recognized by the following attributes:
- A causal relationship is asserted with certainty
- The fact that one event happened first is the only evidence that suggests it caused the next event
- No evidence is provided
- Other contributing factors are ignored or underestimated
Continue reading: How can I identify a post hoc fallacy?
To avoid the either-or fallacy, consider the following questions:
- Are there any other options than the two presented?
- Could a spectrum or middle ground exist between the two extremes?
- Is every possibility being portrayed accurately and with appropriate nuance?
Continue reading: How can you avoid the either-or fallacy?
The either-or fallacy is also known as “false dilemma” or “false dichotomy.” These terms are used interchangeably to describe a common logical fallacy that limits options to just two, overlooking the potential for middle-ground solutions or a spectrum of possibilities.
Continue reading: What is another name for either-or fallacy?
The either-or fallacy is an informal logical fallacy because it is a content-level error that occurs in inductive arguments. Inductive arguments reason from specific observations to propose general principles. If an inductive argument commits an informal fallacy, it is called “unsound.”
By contrast, formal fallacies are structural errors that occur in formal (or deductive) arguments and make the argument “invalid.”
Continue reading: Why is the either-or fallacy an informal logical fallacy?
Logical fallacies that are common in research include the following:
- Hasty generalization: Drawing broad and general conclusions from a small or unrepresentative sample of data
- Fallacy of composition: Assuming that what is true of the parts must be true of the whole
- Post hoc fallacy: Inferring that simply because one event followed another, the first event must have caused the second event
- Ecological fallacy: Forming conclusions about individuals based on group-level data
- False cause fallacy: Inferring a cause-and-effect relationship between two variables when none exists
Continue reading: What are common types of fallacies in research?
The ecological fallacy can occur in the field of epidemiology when individual risk factors or health outcomes are inferred from population-level data. Consider the following example:
- Population-level data: Research indicates that Japan has one of the lowest rates of heart disease globally. The low incidence of heart disease is commonly attributed to healthy lifestyle choices.
- Ecological fallacy inference: A graduate student conducts a study on a small group of test subjects from Japan and assumes that each test subject has a very low risk of heart disease.
Continue reading: What is an example of ecological fallacy in epidemiology?
All ecological fallacies have the following traits:
- They occur in arguments premised on statistics.
- They use group-level statistics to make inferences about individuals.
Continue reading: How do you identify an ecological fallacy?
The appeal to emotion fallacy is problematic because it replaces logic and evidence with emotionally charged content.
Including evocative language and imagery in an argument is an acceptable rhetorical strategy. However, an argument is rendered unsound when an emotional appeal is used to distract from the main points of the argument.
Continue reading: Why is the appeal to emotion fallacy problematic?
