Absolutism: The belief that there are certain unchanging and absolute truths. See subjectivism.
Analogy, argument from: An argument that is based on a likeness between two people, places, events, acts or things. Usually arguments from analogy are used in order to prove that, due to a similarity between two things, these things must be similar in other respects as well.
Anecdotal evidence: Support or evidence for a claim based on limited personal experience.
Antecedent: The “if” component of a conditional statement. The antecedent is always followed by the “then” part of the statement. See conditional statement.
Argument: In philosophy an argument is not a disagreement. Rather, an argument is a claim with reasons that are given in support. If a claim has no support, it is not an argument (see assertion). An argument is made up of two components: premises and a conclusion. See premise and conclusion.
Assertion: An unsupported claim.
Assumption: Usually an implicit or unstated belief. In logic, a built-in assumption is an unstated belief that is presupposed by the premises. For example: “I know that God exists because the Bible states that he does.” In this example, the premise “. . . because the Bible states that He does” contains a built-in assumption: that the Bible is correct.
Belief: A person’s or group’s opinion or conviction about something. Beliefs can be true or false. One can believe that 2 + 2 = 7; this does not mean that it is true. Beliefs can also concern particular tastes or preferences, which are not objectively true or false.
Causal event: An event that is causally related to a following event, such as a pool cue hitting a billiard ball. See non-causal event.
Conclusion: The claim of an argument which uses premises as support.
Conditional statement: An “if-then” statement made up of an antecedent and a consequent. For example: “If it rains, then the car will get wet.”
Conjunctive statement: A statement that combines two distinct components with an “and.” For example: “Dave’s family is German and Lutheran.”
Consequent: The “then” component of a conditional statement, which always follows the “if” part of the statement. See conditional statement.
Contradiction: A contradiction occurs when two statements cannot both be true. For example, if one states that she has never been to London and that she has been to London, both of these statements cannot be true.
Deductive argument: An argument in which the conclusion is necessarily true if the premises are true and if the conclusion follows coherently from them.
Disanalogy: An argument from analogy that is weak due to a lack of similarity between the things compared. Also known as a weak analogy.
Disjunctive statement: An “either-or” statement. For example: “Either Holmes solved the crime or Watson solved the crime.”
Emotive language: Words or phrases specifically used in order to stimulate feelings.
Euphemism: A mild or inoffensive word or phrase substituted for a harsh or unpleasant fact or occurrence. For example, one might speak of “passing away” rather than dying.
Fact: Something that is indisputably true. For example, 2 + 3 = 5 is a fact, and it is also a fact that the earth is spherical.
Fallacy: An error in reasoning or faulty reasoning. There are two types of fallacies: formal and informal.
Falsification: To establish the falsity of a conclusion by introducing a counter-example that proves the conclusion false.
Formal fallacy: An argument that has a flaw in its structure, not in its content.
Hasty conclusion: A conclusion drawn from limited or insufficient evidence.
Inductive argument: An argument in which the truth of the conclusion is only probable.
Informal fallacy: An argument that contains a flaw in the content of the premises or conclusion. This often occurs due to built-in assumptions, omission or intrusion.
Informative language: Language that seeks to inform rather than to arouse feelings.
Invalid argument: A deductive argument in which the truth of the premises does not ensure the truth of the conclusion.
Law of non-contradiction: A basic law of logic stating that two statements cannot contradict each other and at the same time both be true. See contradiction.
Logic: The art or science of argumentation. Also, the study of methods used to arrive at correct conclusions.
Necessary condition: Any condition that, if absent, guarantees that an event will not occur. For example, a necessary condition for rain is the presence of clouds. (However, clouds do not guarantee that it will rain.) See sufficient condition.
Non-causal event: An event that does not necessarily have an effect, such as a coin toss. See causal event.
Non sequitur: Latin for “it does not follow.” A non sequitur is any conclusion that does not follow logically from the premises.
Objective claim: A proposition that is not subjective. A truth claim that is not dependent on a specific individual’s beliefs.
Philosophy: From the Greek, translated as the “love of wisdom.” To practice philosophy is to think critically and to question beliefs, knowledge, truth and other important aspects of human life. Socrates (470-399 BCE) is said to be the “father” of Western philosophy. His most famous statement was: “The unexamined life is not worth living” (Apology, 38a). A philosopher is one who sincerely examines his or her life and life itself.
Premise: Facts or evidence from which a conclusion is derived. Premises are the foundation upon which a conclusion rests.
Proposition: The truth or falsehood expressed in a sentence.
Rationalization: The practice of making an excuse for one’s behavior even when one knows he or she is in the wrong.
Reductio ad absurdum: From the Latin “reduction to the absurd.” An argument that claims a statement should be dismissed if its consequences are illogical or “absurd.”
Reason: 1. Evidence or premises in an argument. 2. The human capacity to think logically and rationally.
Rhetoric: The art of persuasive speaking or writing. The rhetorician’s primary concern is effectively persuading an audience. This may mean he or she is willing to use fallacious arguments, emotive language and/or unsupported assertions in order to persuade.
Scapegoating: Occurs when one places the blame for a negative effect onto a person or group who are not responsible for it.
Semantics: The study of meaning in language. See syntax.
Signifier/Signified: A signifier is a word or linguistic term; signified is the mental concept that the signifier represents. For example, one might use the word “God” (signifier) to represent the idea of a transcendent, all-powerful being (signified).
Soundness: An argument is sound when it is valid and its premises are true.
Statement: A sentence that is either true or false.
Strong argument: An inductive argument in which is it probable, but not necessary, that the conclusion is true if indeed the premises are true.
Subjective claim: A proposition that is not objective. A truth claim that is dependent on a specific individual’s beliefs.
Subjectivism: The belief that truth is entirely dependent on the subject or individual. See absolutism.
Sufficient condition: Any condition that, if present, guarantees that an event will occur. For example, decapitation of a human is a sufficient condition for death. In contrast, a gunshot is not a sufficient condition for death. One can be shot and still survive.
Syllogism: An argument made up of three components: two premises and a conclusion. The most famous example is:
Premise 1: All humans are mortal.
Premise 2: Socrates is a human.
Conclusion: Socrates is mortal.
Syntax: The rules and characteristics of sentence structure. See semantics.
Truth: In logic, a belief, statement, or proposition is true if it accurately describes how things actually are. See subjectivist fallacy on page 30.
Valid argument: An argument with valid structure or form. A deductive argument is valid if the truth of the premises logically ensures the truth of the conclusion. Validity is not a guarantor of truth, however. An argument may be valid and also contain false premises.
Verification: To establish the truth of a conclusion by empirical observation.
Weak argument: An inductive argument in which it is unlikely that the conclusion is true, even if the premises are true.