Fallacies of Presumption and Fallacies of Ambiguity

1. Fallacies of Presumption and Fallacies of Ambiguity

2. Fallacies of Presumption

3. Fallacies of Presumption • There is an unjustified assumption on which the conclusion is based.

4. Fallacies of Presumption • Accident • Complex Question • Begging the Question

5. [1] Accident • One applies a generalization to an individual case that does not fall under it.

6. [2] Complex Question • One argues by asking a question in such a way as to assume the truth of a detail buried in the question.

7. [3] Begging the Question • One assumes in the premises of his argument the truth of what his conclusion.

8. Fallacies of Ambiguity

9. Fallacies of Ambiguity • A term may have one meaning in the premises and a different one in the conclusion. • The change in meaning may be accidental or deliberate.

10. Fallacies of Ambiguity • Equivocation • Amphiboly • Accent • Composition • Division

11. [1] Equivocation • The same word or phrase is used with two or more meanings, deliberately or accidentally, in formulating an argument.

12. [2] Amphiboly • One of the statements in an argument has more than one plausible meaning, because of the loose or awkward way in which the words have been combined.

13. [3] Accent • A shift of meaning arises within an argument as a consequence of changes in the emphasis given to its words or parts.

14. [4] Composition • One reasons that the qualities of a part apply to the whole • One reasons that the qualities of an individual member apply to the group.

15. [5] Division • One reasons that the qualities of the whole apply to its parts • One reasons that the qualities of a group or collection apply to the individual members.