Logically Speaking

Course Guide for Dr. Smith's Logic and Critical Thinking Class
Glossary
Affirming the Consequent: an invalid conditional argument of the form
A-->B B A
Antecedent: the first part of a conditional claim (If A)
Argument: the purpose of an argument is to persuade others of your reasoning; an argument is a form of persuasion that makes a claim and gives reasons in support of that claim
Claim: a statement that is true or false; remember that your premises and conclusions are all claims
Cogent argument: a good argument; there are three criteria of a cogent argument
Conclusion: the claim that is being argued for
Conditional Arguments: an argument with at least one premise that is a conditional claim; there are 4 main ways of reasoning with conditionals that either affirm or deny one of the conditions: modus ponens, modus tollens, affirming the consequent, and denying the antecedent; there is one other way of reasoning with conditionals: the hypothetical syllogism
Conditional Claim: an if-then claim; a claim in the form of 'if A, then B' ; sometimes called a hypothetical proposition; this is symbolically written as "A-->B"
Consequent: the second part of a conditional claim (then B)
Contingent Claim: a claim whose truth value depends on the evidence
Contradiction: a claim that is necessarily false
Criteria of a Cogent Argument (3): believable premises, all the relevant information has to be considered, and the premises must lead to the conclusion
Deductive Argument: an argument where, if the premises are true, the conclusion must be true; the intent of a deductive argument is, assuming that the premises are true, what can we deduce with 100% certainty from those premises?
Denying the Antecedent: a valid conditional argument of the form
A-->B ~A ~B
Disjunction: an either/or claim; either A is the case, or B is the case, where one or the other must be true; symbolically this is written A v B, where 'v' is called a wedge; the terms of a disjunction are called disjuncts
Disjunctive syllogism: a valid form of reasoning from a disjunction, of the form
A v B ~A B
Evidence: a secondary level of support in an extended argument; it's the support given for the main reasons why we should believe the thesis of an extended argument
Extended Argument: a complex argument with more than one level of support given to an overall conclusion
Fallacious argument: a bad argument, which occurs when one of the three criteria of a cogent argument is not fulfilled
Fallacy: an error in our reasoning; there are both formal and informal fallacies
Formal Fallacy: a error in the form (structure) of the argument
Hypothetical Syllogism: a valid conditional argument of the form
A-->B B-->C A-->C
Indicator words: words in ordinary dialog that give us a clue that either a conclusion or premise is about to be given; conclusion indicators include therefore, thus, so, and it follows that; premise indicators include because, since, and for
Inductive Argument: an argument where, if the premises are true, the conclusion is, at best, probably true; the purpose of an inductive argument is to recognize patterns; this is done by observing evidence, and our conclusions are always less than 100% certain
Informal Fallacy: an error in the content, rather than the structure, of an argument
Modus Ponens: a valid conditional argument of the form
A-->B A B
Modus Tollens: a valid conditional argument of the form
A-->B ~B ~A
Necessary Condition: the condition found in the consequent of a conditional claim (B-term); the condition without which the A-term could not be present; a necessary ingredient, in some cases, of the A-term
Predicate: the part of a sentence that is the description
Premise: a claim that is the reason given in support of a conclusion
Reasons: support given for a conclusion; the main reasons in support of a thesis in an extended argument are called 'reasons'; the support for the 'reasons' in an extended argument we'll call 'evidence'; the support for a conclusion in a simple argument are 'premises'
Reasoning: the purpose of reasoning is to solve problems
Simple Argument: an argument with only one level of support given for the conclusion
Strong argument: an inductive argument is said to be strong when the premises lead to the conclusion (with great likelihood); this is because of the strength of the evidence that leads to the inference
Subject: the part of a sentence that is being described
Sufficient Condition: the condition in the antecedent of a conditional claim (A-term); to be a sufficient condition is to give sufficient reason to believe that all of the necessary conditions are present
Tautology: a claim that is necessarily true
Thesis: the overall conclusion of an extended argument
Truth value: 'true' and 'false' are the two truth values
Valid argument: a deductive argument is called valid when the premises lead to the conclusion
Weak argument: an inductive argument is said to be weak when the premises do not lead to the conclusion with much likelihood, due to a lack of strength of evidence supporting the inference
Course Schedule and Contents
1. SiCKo
2. Reasoning and Arguments subject, predicate, reasoning, argument, deductive argument, inductive argument, claim, tautology, contradiction, contingent claim, truth value, cogent argument, criteria of a cogent argument (3), fallacious argument, fallacy, thesis, reason, evidence
3. Conditional Reasoning conditional claim, antecedent, consequent, sufficient condition, necessary condition, 4 main ways of reasoning with conditionals, modus ponens, modus tollens, affirming the consequent, denying the antecedent, hypothetical syllogism, disjunction, disjunctive syllogism