Introduction: Arguments can be wrong in ways that do not violate formal validity (defined as the logical entailment of a conclusion by its premises), and these are called informal fallacies. A fallacy can be understood as a “defective inference,” and informal fallacies are common errors of reasoning which undercut the cogency or credibility of a given argument (Fogelin and Sinnott-Armstrong, 2005). Below are several common fallacies that bioethical reasoning might fall prey to.
Slippery Slope Arguments:
Slippery slope arguments attempt to show that a succession of things is indistinct, allowing increasingly extreme comparison of cases, and they can be either fallacious or non-fallacious. Often, they take the form of hypotheticals: (e.g., “if you accept A, then you should accept B. If you accept B, you should accept C…”). Ex.
“If we allow parents to selectively abort on the basis of prenatal genetic tests which evidence congenital birth defects, it’s only a matter of time before people will be using in-vitro fertilization to select for eye color, or intellect, or athleticism, and then before you know it, we’ll have a society full of designer babies!”
This slippery slope can be read in a few ways. Most likely, it is a causal slippery slope. In a causal slippery slope, the argument is that allowing selective abortion on the basis of prenatal genetic tests will inevitably lead to greater license for parents to abort or select for their children. That said, the argument could also be interpreted as a conceptual slippery slope wherein the question is (implicitly) raised: is there really a difference between selecting against disabilities and selecting for genetic advantages? If we accept the former, why would we not accept the latter? (Fogelin and Sinnott-Armstrong, 2005).
Is the above example fallacious or not? When deciding whether a slippery slope argument is fallacious, it is important to test whether each ‘step’ of the chain of comparisons holds up to scrutiny. A –> B may work, and C –> D may work, but if B –> C does not work, then the whole chain has been rendered defective (Fogelin and Sinnott-Armstrong, 2005).
Argument from Authority:
An argument from authority is one in which the arguer appeals to some expertise or authority to buttress one’s own argument. In principle, nothing is inherently fallacious about appealing to a person or institution possessing technical expertise or privileged knowledge, but the appeal can be abused. Sometimes, the authority being appealed to is not relevant to the question at hand; a celebrity’s popularity or acting role is not grounds for thinking their endorsement carries special weight (e.g., Chris Pratt playing an ethologist in Jurassic World would not qualify him to endorse a zoo’s research division) (Fogelin and Sinnott-Armstrong, 2005). Other times, the authority appealed to is relevant, but the argumentative form is still unpersuasive. Ex:
Speaker A: “Periviability, the earliest point at which a fetus can be expected to survive outside the womb, seems like an arbitrary threshold for acknowledging fetal rights or moral interests, especially because it is a moving target. Continually improving neonatal care techniques will allow us to ensure the survival of earlier and earlier premature births, and I see no reason why that should matter for whether the fetus has moral status or not.”
Speaker B: “Listen, well respected and published bioethicists have established periviability as an important threshold morally and that’s all there is to it.”
That well-respected and published bioethicists put stock in periviability as a determinant of moral status may provide Speaker A with good reason to think that there is more merit to the idea than she is currently aware of, but that fact alone does not contradict or debunk the argument she put forward, and so Speaker B has given no decisive reason for Speaker A to forfeit her position.
Circular Reasoning or Begging the Question:
In circular reasoning, “the conclusion, or some statement synonymous with the conclusion, is used as a premise,” making the inference tautological. It is a defective inference because it presupposes the very point at issue, which needs independent justification (Fogelin and Sinnott-Armstrong, 2005). Ex:
“A physician must always champion the patient’s freedom to make their own medical decisions, because it is a patient’s right to choose whether to receive treatment or have it withdrawn.”
In this quote, the patient’s “right to choose whether to receive treatment or have it withdrawn” is really just a restatement of the first clause concerning the patient’s “freedom to make their own medical decisions.” It may be true that a physician is obligated to promote patient choice and medical autonomy, but as quoted earlier, this argument is ultimately vacuous because it “doesn’t get anywhere” (Fogelin and Sinnott-Armstrong, 2005).
Strawperson (“Strawman”):
A strawman fallacy occurs when a rebuttal appears to defeat an argument or demonstrate its absurdity, but only a much inferior or misconstrued form of the argument than is actually being posed by one’s opponent. A straw man fallacy can include, but is not limited to, “exaggeration or misquotation, as well as other forms of distortion of an opponent’s position” (Walton, 2008). Ex:
Speaker A: “We should expand the existing legal provisions for aid in dying to include non-terminal patients, because those with terminal illnesses do not have a monopoly on chronic, intolerable suffering.”
Speaker B: “So you’re saying physicians should offer euthanasia to anyone who walks in the door asking for it?”
Speaker B here is either deliberately misrepresenting, or assuming beyond what they have evidence to believe, the position of speaker A. Speaker A states only that aid in dying ought to be expanded, but speaker B insinuates that Speaker A is recommending universal access to aid in dying. Speaker B also conflates aid in dying with euthanasia when speaker A only comments upon the former.
False Dichotomy:
A false dichotomy occurs whenever an argument hinges on a false binary between two options. False dichotomies are disjunctive propositions lacking soundness, taking the form: “either A is true, or B is true” when, in truth, there are alternatives to A or B being true. C could be true, or some compromise between A and B could be true. Ex:
“Either all living organisms have moral status, or no living organisms have moral status!”
Moral status need not be all or nothing. It is possible to propose criteria by which some living organisms possess moral status, and some do not, or by which organisms deserve differential amounts of moral concern. Maybe the distinguishing criterion is having interests, or being sentient, or having the capacity of nociception or suffering, or some other quality or combination thereof (Singer, 1975). It is thus a false dichotomy to assert that no meaningful distinctions could be drawn between submicroscopic viruses and highly sophisticated mammalia.
Ad Hoc Fallacy:
Ad hoc fallacies are arguments wherein “an implausible view is accepted only in order to defend another belief” (Gensler, 2010). Often, Ad hoc arguments introduce an additional premise or sub-argument in order to save the overarching argument, but in a way that does not generalize outside the context at hand. Ex:
“The reason humans have moral status and animals do not is because humans have the highest intellect of any species and possess unique reasoning capacities. Therefore, it is permissible for humans to kill and eat animals.”
This argument is a logically valid justification for meat-eating, but it is conspicuously suited for justifying meat eating and little else. If an alien species came to earth possessing even higher intellect and superior reasoning faculties, would humans cease to possess moral status? Would the aliens be permitted to eat us? Moreover, when humans, due to cognitive disability or injury, fall below the intellectual performance of most other humans, we do not treat them as having lost their moral status. Thus, without further explanation, the argument fails by way of lacking generalizability.
For exercises in identifying these informal fallacies, click the link below to download!
Works Cited
Gensler, Harry J. The A to Z of Logic. Lanham, Md.: Scarecrow Press, 2010.
Fogelin, Robert J., and Walter Sinnott-Armstrong. Understanding Arguments: An Introduction to Informal Logic. 7th ed. Australia; Belmont, CA: Thomson Wadsworth, 2005.
Walton, Douglas N. Informal Logic: A Pragmatic Approach. 2nd ed. Cambridge; New York: Cambridge University Press, 2008.
Singer, Peter, 1975, Animal Liberation, New York: Harper Collins.