Logical fallacies are errors of reasoning—specific ways in which arguments fall apart due to faulty connection making. While logical fallacies may be used intentionally in certain forms of persuasive writing (e.g., in political speeches aimed at misleading an audience), fallacies tend to undermine the credibility of objective scholarly writing. Knowledge of how successful arguments are structured, then—as well as of the different ways they may fall apart—is a useful tool for both academic reading and writing. If you are writing an annotated bibliography or literature review, for instance, being able to recognize logical flaws in others‘ arguments may enable you to critique the validity of claims, research results, or even theories in a particular text. Along the same lines, if you are putting together your own argumentative paper (KAM, dissertation proposal, prospectus, etc.), understanding argument structure and fallacies will help you avoid errors of reasoning in your own work.
The basic structure of all arguments involves three interdependent elements:
- Claim (also known as the conclusion)—What you are trying to prove. This is usually presented as your essay‘s thesis statement.
- Support (also known as the minor premise)—The evidence (facts, expert testimony, quotes, and statistics) you present to back up your claims.
- Warrant (also known as major premise)—Any assumption that is taken for granted and underlies your claim.
Consider the claim, support, and warrant for the following examples:
Claim: The No Child Left Behind Act (NCLB, 2001) has led to an increase in high school student drop-out rates.
Support: Drop-out rates in the US have climbed by 20% since 2001.
Warrant: (The claim presupposes that) it‘s a "bad" thing for students to drop out.
Claim: ADHD has grown by epidemic proportions in the last 10 years
Support: In 1999, the number of children diagnosed with ADHD was 2.1 million; in 2009, the number was 3.5 million.
Warrant: (The claim presupposes that) a diagnosis of ADHD is the same thing as the actual existence of ADHD; it also presupposes that ADHD is a disease.
Claims fall into three categories: claims of fact, claims of value, and claims of policy. All three types of claims occur in scholarly writing although claims of fact are probably the most common type you will encounter in research writing. Claims of fact are assertions about the existence (past, present, or future) of a particular condition or phenomenon:
Example: Japanese business owners are more inclined to use sustainable business practices than they were 20 years ago.
The above statement about Japan is one of fact; either the sustainable practices are getting more popular (fact) or they are not (fact). In contrast to claims of fact, those of value make a moral judgment about a phenomenon or condition:
Example: Unsustainable business practices are unethical.
Notice how the claim is now making a judgment call, asserting that there is greater value in the sustainable than in the unsustainable practices. Lastly, claims of policy are recommendations for actions—for things that should be done:
Example: Japanese carmakers should sign an agreement to reduce carbon emissions in manufacturing facilities by 50% by the year 2025.
The claim in this last example is that Japanese carmakers‘ current policy regarding carbon emissions needs to be changed.
For the most part, the claims you will be making in academic writing will be claims of fact. Therefore, examples presented below will highlight fallacies in this type of claim. For an argument to be effective, all three elements—claim, support, and warrant—must be logically connected.
Although there are more than two dozen types and subtypes of logical fallacies, many of these are likelier to occur in persuasive, rather than expository or research, writing. Below are the most common forms of fallacy that you may encounter in the type of expository/research writing you are apt to do at Walden:
- Begging the question, also known as circular reasoning, is a common fallacy that occurs when part of a claim—phrased in just slightly different words—is used in support of that same claim.
Example: Special education students should not be required to take standardized tests because such tests are meant for nonspecial education students.Notice how the author‘s claim (x should not take the exams) merely presupposes what it is supposed to be proving: that x should not take the exams. This type of fallacy shows up in dissertation prospectus problem statements in which the problem and its cause are defined to be the same.
- Hasty generalization is an error of induction that occurs when a writer jumps to an inference based on limited or inadequate data. Something to pay attention to when reviewing research design (for instance, when doing a literature review or an article critique) is whether the authors of the research paper have based their conclusions on unreliable data or too small a sample size.
Example: Two out of three patients who were given green tea before bedtime reported sleeping more soundly. Therefore, green tea may be used to treat insomnia.In this example, a sample size of three is way too small to generalize about the effectiveness of green tea—not to mention that patients' self-reports do not always make the most reliable data!
- Sweeping generalizations are related to the problem of hasty generalizations. In the former, though, the error consists in assuming that a particular conclusion drawn from a particular situation and context applies to all situations and contexts. For example, if I research a particular problem at a private performing arts high school in a rural community, I need to be careful not to assume that my findings will be generalizable to all high schools, including public high schools in an inner city setting.
- Non sequitur is a Latin term that means "does not follow," and the fallacy occurs when no true logical (especially cause-effect) relationship exists between two notions.
Example: Professor Berger has published numerous articles in immunology. Therefore, she is an expert in complementary medicine.Notice, in this example, that there is no necessary relationship between knowledge of immunology on the one hand and expertise in complementary medicine on the other. It does not follow that Dr. Berger will be an expert in both areas.
- Post hoc ergo propter hoc, another Latin term, means "after this; therefore, because of this." This fallacy results from assuming that because something chronologically follows something else, then the two things must be related by a cause-effect connection. Just because x follows y in time, though, does not mean that y caused x. If we look back to the very first example about the NCLB Act, we can see the claim is founded on this false assumption:
Example: Drop-out rates increased the year after NCLB was passed. Therefore, NCLB is causing kids to drop out.Although it may be true NCLB is contributing to drop outs, this cannot be concluded by the chronology of events alone. Correlation is not causation, so the cause-effect connection would have to be proven. For all we know, some third variable may have caused both the passage of the Act and the change in drop-out rate.
- False dilemma, also known as black and white fallacy, results when a writer falsely constructs an either-or situation. Claims of policy are especially prone to false dilemma errors as the following example shows:
Example: Japanese carmakers must implement green production practices, or Japan‘s carbon footprint will hit crisis proportions by 2025.The writer of this claim of policy assumes that there are only two options—green car production on the one hand or a catastrophic carbon footprint on the other. However, it is likely that car production is only one of many, many factors contributing to Japan‘s carbon emissions problem. It is unreasonable to focus so absolutely on this one factor.
In addition to claims of policy, false dilemma seems to be common in claims of value. For example, claims about abortion‘s morality (or immorality) presuppose an either-or about when "life" begins. Our earlier example about sustainability ("Unsustainable business practices are unethical.") similarly presupposes an either/or: business practices are either ethical or they are not, it claims, whereas a moral continuum is likelier to exist.
As you can see from the examples above, there are many ways arguments can fall apart due to faulty connection making. When trying to induce inferences from data, for instance, it‘s important not to draw conclusions too quickly or too globally; otherwise, you may end up with errors of hasty or sweeping generalization that will weaken your overall thesis. Similarly, it‘s important not to construct an either-or argument when dealing with a complex, multi-faceted issue or to assume a causal relationship when dealing with a merely temporal one; the ensuing errors—false dilemma and post hoc ergo procter hoc, respectively—may weaken argument as well. Being attentive to logical fallacies in others‘ writings will make you a more effective "critic" and writer of literature review assignments, annotated bibliographies and article critiques. Being attentive to fallacies in your own writing will help you build more compelling arguments, whether putting together a dissertation prospectus or simply writing a short discussion post on the applications of a particular theory.