Typically, this term refers to a rhetorical strategy where the speaker attacks the character, motive, or some other attribute of the person making an argument rather than addressing the substance of the argument itself. The most common form of ad hominem is "A makes a claim x, B asserts that A holds a property that is unwelcome, and hence B concludes that argument x is wrong".
Valid ad hominem arguments occur in informal logic, where the person making the argument relies on arguments from authority such as testimony, expertise, or a selective presentation of information supporting the position they are advocating. In this case, counterarguments may be made that the target is dishonest, lacks the claimed expertise, or has a conflict of interest. Another type of valid ad hominem argument generally only encountered in specialized philosophical usage refers to the dialectical strategy of using the target's own beliefs and arguments against them, while not agreeing with the validity of those beliefs and arguments. Since the validity of an argument is found within its content, which stands apart from any property of the one making the argument, these 'valid' ad hominem exceptions are of questionable validity regardless of rhetorical effect.
The various types of ad hominem arguments have been known in the West since at least the ancient Greeks. Aristotle, in his work Sophistical Refutations, detailed the fallaciousness of putting the questioner but not the argument under scrutiny. Many examples of ancient non-fallacious ad hominem arguments are preserved in the works of the Pyrrhonist philosopher Sextus Empiricus. In these arguments, the concepts and assumptions of the opponents are used as part of a dialectical strategy against the opponents to demonstrate the unsoundness of their own arguments and assumptions. In this way, the arguments are to the person (ad hominem), but without attacking the properties of the individuals making the arguments.
Italian polymath Galileo Galilei and British philosopher John Locke also examined the argument from commitment, a form of the ad hominem argument, meaning examining an argument on the basis of whether it stands true to the principles of the person carrying the argument. In the mid-19th century, the modern understanding of the term ad hominem started to take shape, with the broad definition given by English logician Richard Whately. According to Whately, ad hominem arguments were "addressed to the peculiar circumstances, character, avowed opinions, or past conduct of the individual".
The earlier notion of ad hominem arguments would be maintained among later Catholic Aristotelian scholastics, into the 19th century and even the 20th century. For instance, the Dominican friar and Cardinal, Tommaso Maria Zigliara, doubtlessly drawing on earlier scholastic discussions, distinguished between absolute and relative demonstrations, referring to the latter as ad hominem arguments: “An ‘absolute’ demonstration is one which proceeds from premises whose truth we admit and assume in order to then draw an inference, absolutely speaking, as when we demonstrate the real existence of God on the basis of the contingent character of creatures, and other such demonstrations. However, a relative (that is, ad hominem) demonstration is one which proceeds from principles which are admitted by the person we are arguing against and which we assume for the sake of refutation, setting aside the question of the truth of such principles, as when someone assumes principles admitted by materialists or by rationalists, in order to convince them that their doctrine is false.”
Over time, the term acquired a different meaning; by the beginning of the 20th century, it was linked to a logical fallacy, in which a debater, instead of disproving an argument, attacked their opponent. This approach was also popularized in philosophical textbooks of the mid-20th century, and it was challenged by Australian philosopher Charles Leonard Hamblin in the second half of the 20th century. In a detailed work, he suggested that the inclusion of a statement against a person in an argument does not necessarily make it a fallacious argument since that particular phrase is not a premise that leads to a conclusion. While Hablin's criticism was not widely accepted, Canadian philosopher Douglas N. Walton examined the fallaciousness of the ad hominem argument even further. Nowadays, except within specialized philosophical usages, the usage of the term ad hominem signifies a straight attack at the character and ethos of a person, in an attempt to refute their argument.
The terms ad mulierem and ad feminam have been used specifically when the person receiving the criticism is female.
Fallacious ad hominem reasoning is categorized as an informal fallacy, more precisely as a genetic fallacy, a subcategory of fallacies of irrelevance. Several types of ad hominem fallacies exist. All of these follow a general scheme where instead of dealing with the essence of someone's argument or trying to refute it, the interlocutor attacks the character of the proponent of the argument and concludes that the attack refutes the argument.
Circumstantial ad hominem is an attack on the bias of a source. It points out that someone is in a circumstance (for instance, their job, wealth, property, or relations) such that they are disposed to take a particular position. A simple example is: a father may tell his daughter not to start smoking because she will damage her health, and she may point out that he is or was a smoker. This does not alter the fact that smoking might cause various diseases. Her father's inconsistency is not a proper reason to reject his claim.
Circumstantial ad hominem arguments are not necessarily fallacious. They can be fallacious because a disposition to make a certain argument does not make the argument invalid (this overlaps with the genetic fallacy – an argument that a claim is incorrect due to its source). They can also be sound arguments if the premises are correct and the bias is relevant to the argument. This could be the case when someone (A) attacks the personality of another person (B), making an argument (a) while the personality of B is relevant to argument a, for example, B speaks from their position as an authority figure.
Appeal to motive is a special case of the ad hominem circumstantial argument in which an argument is challenged by calling into question the motives of its proposer.
Ergo decedo, Latin for "therefore leave" or "then go off", a truncation of argumentum ergo decedo, also known as the traitorous critic fallacy, denotes responding to the criticism of a critic by implying that the critic is motivated by undisclosed favorability or affiliation to an out-group, rather than responding to the criticism itself. The fallacy implicitly alleges that the critic does not appreciate the values and customs of the criticized group or is traitorous, and thus suggests that the critic should avoid the question or topic entirely, typically by leaving the criticized group.
Guilt by association, that is accusing an arguer because of his alleged connection with a discredited person or group, can sometimes also be a type of ad hominem fallacy when the argument attacks a source because of the similarity between the views of someone making an argument and other proponents of the argument.
This form of the argument is as follows:
Academic Leigh Kolb gives as an example that the 2008 US vice‐presidential candidate Sarah Palin attacked Barack Obama for having worked with Bill Ayers, who had been a leader in the Weather Underground terrorist group in the 1960s. Despite Obama denouncing every act of terrorism, he was still associated by his opponents with terrorism.
Guilt by association is frequently found in social and political debates. It also appears after major events (such as scandals and terrorism) linked to a specific group. An example, given also by Leigh Kolb, is the peak of attacks against Muslims in the US after the September 11 attacks.
Ad hominem tu quoque (literally: "You also") is a response to a personal attack (or ad hominem argument) that itself is a personal attack.
Tu quoque appears as:
Here is an example given by philosophy professor George Wrisley to illustrate the above: A businessman and politician is giving a lecture at a University about how good his company is and how nicely the system works. A student asks him "Is it true that you and your company are selling weapons to third world rulers who use those arms against their own people?" and the businessman replies "is it true that your university gets funding by the same company that you are claiming is selling guns to those countries? You are not a white dove either". The ad hominem accusation of the student is relevant to the narrative the businessman tries to project thus not fallacious. On the other hand, the attack on the student (that is, the student being inconsistent) is irrelevant to the opening narrative. So the businessman's tu quoque response is fallacious.
Canadian philosopher Christopher Tindale approaches the tu quoque fallacy somewhat differently. According to Tindale, a tu quoque fallacy appears when a response to an argument is made concerning the history of the arguer. This argument is also invalid because it does not disprove the premise. If the premise is true, then source A may be a hypocrite or even may have changed their mind, but this does not make the statement less credible from a logical perspective. A common example, given by Tindale, is when a doctor advises a patient to lose weight, but the patient argues that there is no need for him to go on a diet because the doctor is also overweight.
Whataboutism, also known as whataboutery, is a variant of the tu quoque logical fallacy that attempts to discredit an opponent's position by charging them with hypocrisy without directly refuting or disproving their argument.
The term "ad hominem" is sometimes used to refer to abusive language which is not directly connected to an argument over a particular proposition. For example, a politician who refers to an opponent as "a crook", might be accused of arguing "ad hominem".
Poisoning the well (or attempting to poison the well) is a type of informal fallacy where adverse information about a target is preemptively presented to an audience with the intention of discrediting or ridiculing something that the target person is about to say. The term was first used in the sense of an ad hominem by John Henry Newman in his work Apologia Pro Vita Sua (1864). The origin of the term lies in well poisoning, an ancient wartime practice of pouring poison into sources of fresh water before an invading army, to diminish the attacked army's strength.
An ad hominem argument from commitment is a type of valid argument that employs, as a dialectical strategy, the exclusive utilization of the beliefs, convictions, and assumptions of those holding the position being argued against, i.e., arguments constructed on the basis of what other people hold to be true. This usage is generally only encountered in specialist philosophical usage or in pre-20th century usages. This type of argument is also known as the ex concessis argument (Latin for "from what has been conceded already").
Ad hominem arguments are relevant where the person being criticised is advancing arguments from authority, or testimony based on personal experience, rather than proposing a formal syllogism.
An example is a dialogue at the court, where the attorney cross-examines an eyewitness, bringing to light the fact that the witness was convicted in the past for lying. This might suggest the conclusion that the witness should not be trusted, which would not be a fallacy.
Ad hominem fallacies are considered to be uncivil and do not help create a constructive atmosphere for dialogue to flourish. An ad hominem attack is an attack on the character of the target, who tends to feel the necessity to defend himself or herself from the accusation of being hypocritical. Walton has noted that it is so powerful an argument that it is employed in many political debates. Since it is associated with negativity and dirty tricks, ad hominem attacks have erroneously been assumed to always be fallacious.
Eithan Orkibi describes two forms of ad hominem attacks that are common during election periods. The first is the precedent ad hominem, according to which the previous history of someone means that they are not fit for the office. For example: "My opponent was (allegedly) wrong in the past, therefore he is wrong now". The second one is a behavioral ad hominem: "My opponent was not decent in his arguments in the past, so now he is not either". These kinds of attacks are based on the inability of the audience to have a clear view of the amount of false statements by both parties of the debate.
Walton has argued that ad hominem reasoning is not always fallacious, and that in some instances, questions of personal conduct, character, motives, etc., are legitimate and relevant to the issue, as when it directly involves hypocrisy, or actions contradicting the subject's words.
The philosopher Charles Taylor has argued that ad hominem reasoning (discussing facts about the speaker or author relative to the value of his statements) is essential to understanding certain moral issues due to the connection between individual persons and morality (or moral claims), and contrasts this sort of reasoning with the apodictic reasoning (involving facts beyond dispute or clearly established) of philosophical naturalism.
Origin - 1990s: from the way in which counter-accusations may take the form of questions introduced by 'What about —?'. ... Also called whataboutery