Relationship between Thoughts

1. Relationship between Thoughts • Critical thinking or reasoning is a process of actively linking thoughts together in the belief that one thought supports another thought. The relationship between thoughts is the primary concern of critical thinking or reasoning. • The active process of establishing a relationship between thoughts is referred to as inference. To infer is to say that one thought supports, justifies, or makes it reasonable to believe in the truth of another thought. • When an inference is expressed in statements, that is, sentences used to make claims that may be true or false, it is called an argument. • An argument is a set of statements that claims that one or more of those statements, known as premises, support another statement, known as the conclusion. • The evaluation of an argument comprises two distinct and essential considerations: • Do the premises support the conclusion? • Are the premises true?

2. Inferential Connection in an Argument • The first concern in the logical evaluation of arguments is to determine the inferential connection between premises and the conclusion, that is, if the premises really support the conclusion. • If the premises of any argument do not support the conclusion, or if the conclusion does not follow from its premises, then the argument logically disintegrates and is not worthy of further consideration. Such an argument is known as a non sequitur (Latin: does not follow): • In a non sequitur, the conclusion could be either true or false, but the argument is fallacious because of the disconnection between the premise(s) and the conclusion. .

3. Examples of Non-Sequitur • Daughter says to her father: “If you really loved me, you would buy me a car.” • Husband says to his wife: “You will do what I say because you are my wife.” • A recent political argument: “Terrorists attacked America. There are terrorists in Iraq. Therefore, the United States is justified in invading Iraq.” • Example of undistributed middle in a faulty syllogism: • All university professors are human. • Toronto Mayor Rob Ford is human. • Therefore, Mayor Ford is a university professor. Even though the above premises are true, the conclusion does not follow from the premises, rendering the argument a non-sequitur. • Even if the conclusion is also true, a non sequitur results if the conclusion does not absolutely follow from the premises as in the following argument: • All university professors are human. • Cinema Studies Institute Director Charlie Keil is human. • Therefore, Charlie Keil is a university professor. • For this argument to be deductively valid would require an additional premise: • All humans are university professors. • Both of the above syllogisms represent a logical fallacy of the undistributed middle because the “middle” terms – being human – do not necessarily connect professors with Rob Ford or Charlie Keil.

4. JFK Assassination Non Sequitur • The shots that killed President Kennedy and wounded Governor Connally were fired from the 6th floor of the Texas School Book Depository. • Lee Harvey Oswald worked in the Texas School Book Depository, and Officer Marrion Baker encountered Oswald in the 2nd floor lunchroom within 90 seconds of the shooting. • Oswald resisted arrest and lied to police. • Oswald had attempted to kill General Walker in April 1963. • The shots which killed President Kennedy and wounded Governor Connally were fired by Lee Harvey Oswald. • Even if all of the above statements are true (only the second is undisputed, the conclusion does not follow from the premises. How so?

5. Property of an Argument • The inferential connection between premises and the conclusion of an argument is independent of the property of an argument as a whole, that is, the truth or fallacy of its premises; it is not necessary to know that the premises of an argument are true or false in order to assess its inferential connection. • When the relationship of the premises to the conclusion has been established, then attention can focus on the property of an argument (truth or fallacy of the premises). • Truth or fallacy can be a property of statements but never of inferences (arguments), which must be evaluated by different standards, depending on the type of argument.

6. Types of Argument • The degree of inferential connection between premises and the conclusion can determine the type of argument. Arguments in which the truth of the premises guarantees the truth of the conclusion are known as "deductive" arguments. • But in most arguments, the truth of the premises does not provide absolute guarantee of the truth of the conclusion. Such "inductive" arguments only offer reasons why the conclusion is "probably" true. • In effect, a deductive argument depends on its form or structure, whereas an inductive argument depends on its content. • The nature of the relationship that is presumed to exist between the premises and the conclusion is the key to understanding the difference between deductive or inductive reasoning.

7. Deductive Argument • In a deductive argument, the premises are “intended” to “guarantee” the truth of the conclusion. If the premises are true, then the conclusion is “definitely” true. • The truth of the conclusion is "contained within" the truth of the premises; that is, the conclusion does not go beyond what the truth of the premises implicitly requires, as in the following arguments: • All university professors are intelligent. • Charlie Keil is a university professor. • Therefore, Charlie Keil is intelligent. Or: If it is dark outside at 6 pm in Toronto, it must be winter. • In essence, one is arguing that a general principle, theory, or case applies to a specific instance, case, or conclusion. In effect, it is often said, not always correctly, that in deductive reasoning one is arguing from the general to specific • The support for a deductive argument is usually limited to inferences that follow from definitions, accepted theory or concept, mathematical necessity, and rules of formal logic.

8. Deductive Argument Challenging Warren Commission Conclusion #1 • Premise: According to Newton’s second law of motion, the rate of change of momentum of a body is equal to the resultant force acting on the body and is in the same direction. (According to Newton’s second law of motion, the rate of change of momentum is proportional to the imposed force and goes in the direction of the force.) • Premise: According to the Zapruder film, when hit in the head by a bullet travelling upwards of 2,000 feet per second, President Kennedy was propelled backward and leftward. • Conclusion: President Kennedy was shot by a gunman located to the right and front of him.

9. Validity of Deduction • The first standard for evaluating a deductive argument is “validity.” If the truth of the premises “actually” guarantees the truth of the conclusion, then a deductive argument is considered to be “valid.” • Considering both Newton’s second law of motion and the movement of Kennedy’s head and body depicted in the Zapruder film, no reasonable and objective person would deny that the premises “formally” support the conclusion, thus validating the argument. • Even if one wanted to dispute whether or not President Kennedy’s head and body actually move back and to the left, the deduction is still valid because of the relationship between Newton’s law of motion and Kennedy’s movement. Whether the conclusion is true or false also does not alter the validity of this argument. • The argument would only be rendered invalid if Newton’s law did not pertain to motion and had no relevance to Kennedy’s body movement or if the concern were strictly about the location of Kennedy’s wounds, which does not pertain to Newton’s laws of motion. • Validity is concerned only with the formal relation between premises and conclusion, without considering the question of whether or not the premises or the conclusion are actually true.

10. Soundness of Deduction • The second standard for evaluating a deductive argument is “soundness” If a deductive argument is valid and its premises are actually true, then the argument is considered "sound.“ • The truth of Newton’s second law of motion is not currently in dispute. And, the Zapruder film (frame 313) clearly shows that President Kennedy’s body is driven backward and leftward when apparently struck by a bullet to the head. On this basis, this valid argument is also sound. • Only if a deductive argument is invalid or if its conclusion is based on a false premise or both, then the argument is "unsound.” Some have tried to argue that Kennedy’s head and body actually move forward, thereby rendering the conclusion unsound. Alternative explanations for the backward movement of President’s Kennedy body have been offered in an effort to render the conclusion unsound, including the "jet effect," car acceleration, body limpness, and wind resistance, but none of these has been widely accepted as scientifically compelling proof. • Therefore, the argument concluding that "President Kennedy was shot by a gunman located to the right and front of him" is not only valid but also sound. • In other words, soundness depends on both the validity of the argument and the actual truth of the premises.

11. Inductive Argument • In an inductive argument, the premises are “intended” to “support the probability” of the truth of the conclusion. In other words, if the premises are true, then the conclusion is “probably” true. • Even if the actual truth of the conclusion cannot be confirmed, the truth of the premises offers pertinent, verifiable, and sufficient reason to believe in the probability of the truth of the conclusion. • Therefore, support for an inductive argument can appeal to a wide range of fact, authority, and logic. • Because the conclusion of an inductive argument makes a claim that extends beyond, or is not contained within, its premises, it cannot be measured by the same standard as a deductive argument. • Instead, the standards for evaluating an inductive argument are "strength" and "cogence" ("acceptability").

12. Strength of Induction • If the premises of a conclusion are presumed to be true (if not actually true), then they provide "strong" support for the truth of the conclusion. The logical strength of an argument is independent of the truth or fallacy of its premises; it is not necessary to know that the premises of an argument are true in order to assess its logical strength. • If the relevance of any of the premises is questionable (aside from their actual truth), then they constitute "weak" support for the truth of the conclusion. • Each of the 6 premises (a-e) for conclusion #1 of the Warren Commission Report are relevant to the reasonable support of the conclusion, and therefore the argument can be considered to be formally strong. • If any of the 6 premises did not constitute support conclusion #1, then the conclusion would be formally weakened. • Like validity, strength is concerned only with the formal relation between premises and conclusion, without considering the question of whether or not the premises are actually true.

13. Cogence of Induction • If an inductive argument is strong and its premises are actually true, then the argument is "cogent" ("acceptable" or "compelling"); the term "sound" can also apply in this case. • But if an inductive argument is weak or the conclusion is based on a false premise or both, then the argument is "uncogent" or "not cogent" ("unacceptable" or "not compelling"); the term "unsound" can also apply in this case. • Like soundness, cogence depends on both the strength of the argument and the actual truth of the premises. • Research has shown that each of the six premises of the first conclusion of the Warren Commission Report is debatable, and indeed, substantial evidence can be mobilized to argue that each is false, thereby casting doubt on the cogence or acceptability of the conclusion.

14. Inductive Reasoning Supporting Conclusion 2 • “The weight of the evidence indicates that there were three shots fired” (19). • “The consensus among the witnesses at the scene was that three shots were fired” (110). • “… the nearly whole bullet discovered at Parkland Hospital and the two larger fragments found in the Presidential automobile, which were identified as coming from the assassination rifle, came from at least two separate bullets and possibly from three (110). • “The most convincing evidence relating to the number of shots was provided by the presence on the sixth floor of three spent cartridges which were demonstrated to have been fired by the same rifle that fired the bullets which caused the wounds” (110). • The Warren Commission identifies bullet wounds in Kennedy and Connally only in terms of a three-shot scenario in which two bullet hit the target and in terms of the single-bullet theory, but of which have been seriously questioned almost to the point of being discredited (111-16). • “Since the preponderance of the evidence indicated that three shots were fired, the Commission concluded that one shot probably missed the Presidential limousine and its occupants, and that the three shots were fired in a time period ranging from approximately 4.8 to in excess of 7 seconds” (117). • For the Warren Commission’s “lone gunman” conclusion to be valid, only three bullets could be fired because the Mannlicher-Carcano rifle alleged to have been used could not have accommodated a fourth shot in the available time frame suggested by the Warren Commission.

15. Inductive Reasoning Questioning Conclusion 2 • Several eyewitnesses, the Warren Commission admits, heard more than three shots – various reports indicate 4-9 shots. • Several missed shots (other than the one which the Warren Commission acknowledges superficially wounding bystander James Tague) were reported, some supported by evidence of bullets (or parts thereof) or damage apparently caused by bullets. • Evidence points to President Kennedy incurring at least three distinct bullet wounds, while Governor Connally incurred at least two distinct bullet wounds, all of which indicate five shots fired. The officially recognized missed shot reported by Tague represents a sixth shot. • Acoustic evidence presented to the House Select Committee on Assassinations in 1978 points to a more than 95% probability of at least four shots and likely six. Based on this evidence, the HSCA concluded that President Kennedy was assassinated “probably” as a result of a conspiracy of unknown origins.

16. Assessment of Warren Commission Arguments • Like conclusion 1(a), conclusion 2 is on the surface a strong argument because the premises are related to the conclusion. However, by citing only evidence that tended to support the three-shot scenario, while rejecting or ignoring evidence that contradicted it, the WC casts reasonable doubt upon the accuracy, objectivity, and thoroughness of its investigation and analysis pertaining to conclusion 2. • Just as the first premise of the first conclusion raises significant unanswered or unconsidered questions that cast doubt on the cogence of the argument, so does similar critical analysis of the second conclusion suggests that it represents a strong but uncogent argument. • Indeed, the cogence of all twelve of the conclusions of the Warren Commission Report suffers under such critically objective analysis or evaluation, thereby weakening the whole structure of the argument.

17. Deductive vs Inductive Reasoning • Deductive arguments are either valid or invalid, sound or unsound, and those standards are not debatable. • In inductive arguments, strength and weakness or cogence and uncogence can be in the eyes of the beholder and thus are subject to debate. The same argument can appear to be strong and cogent to one person and weak and uncogent to another. • Because of it definite quality, deduction can be considered to be superior to induction, but that too is debatable. The usefulness of deductive reasoning is limited to exploring the implications of what is already known or assumed to be true. • Genuinely new knowledge can only arise from inductive reasoning. In this respect, inductive reasoning is much more powerful than deductive reasoning, and thus is far more common.