PHIL 105

Informal Fallacies 

Definition and Types of Fallacies 

Fallacy: A defect in an argument that undermines its validity. 

Informal Fallacy: A fallacy that can only be identified by examining the content of the argument, as opposed to its form. 

Formal Fallacy: An error in an argument determined solely by its structure, typically found in deductive arguments. 

Common Informal Fallacies 

Appeal to Force: The arguer claims a conclusion is true due to a threat, rather than evidence or reasoning. 

Appeal to Pity: This fallacy relies on eliciting pity to establish a conclusion, rather than logical reasoning. 

Appeal to the People: An argument that appeals to the desires of people to be loved or respected, often seen in two forms: 

Direct: Addressing a large group to excite emotions. 

Indirect: Targeting individuals to emphasize their relationship to the crowd. 

Specific Examples of Fallacies 

Ad Hominem: Attacking the person making the argument rather than the argument itself, which can take forms such as abusive or circumstantial attacks. 

Straw Man: Distorting an opponent's argument to make it easier to attack, then claiming victory over the original argument. 

Hasty Generalization: Drawing a conclusion about a whole group based on insufficient evidence, e.g., assuming all heavy metal listeners are soft-spoken based on a few examples. 

The Square of Opposition 

Categorical Statements 

Categorical Statements: Four types of categorical statements are defined: 

A: All S are P (Universal Affirmative) 

E: No S are P (Universal Negative) 

I: Some S are P (Particular Affirmative) 

O: Some S are not P (Particular Negative) 

Example: "All dogs are mammals" illustrates a universal affirmative statement. 

Modern vs. Traditional Square of Opposition 

Traditional Square: Assumes propositions refer to existing objects, supporting more inferences based on existential assumptions. 

Modern Square: Does not assume existence, focusing on the logical relationships between propositions. 

Testing Immediate Inferences 

Immediate Inference: A logical deduction made directly from a single statement, such as: 

From "All A are B", one can infer "Some A are B" is valid. 

However, inferring "No A are B" from "Some A are B" is invalid. 

Legal Reasoning 

Principles of Legal Reasoning 

Rule of Law: Everyone is subject to the law, which is enforced impartially by courts. 

Legal Judgments: Must be based on evidence, admissible according to legal standards, and logically adequate. 

Types of Evidence 

Direct Evidence: Establishes the existence of a fact without inference, e.g., 

 eyewitness testimony. 

Indirect Evidence: Allows for inference but does not directly prove a fact, e.g., circumstantial evidence. 

Burden of Proof in Trials 

Criminal Trials: The prosecution must prove guilt beyond a reasonable doubt, while the defense can raise reasonable doubt. 

Civil Cases: The plaintiff must establish a preponderance of evidence, meaning their case must be more convincing than the defendant's.