04第四讲 命题与推理概述

1、定义。An argument, as it occurs in logic, is a group of statements, one or more of which (the premises) are claimed to provide support for, or reason to believe, one of the others (the conclusion). 2、构成：前提 、结论、（推出关系 ）。The premises are the statements that set forth the reason or evidence, and the conclusion is the statement that the evidence is claimed to support or imply. Premises can be distinguished from conclusion by the occurrence of indicator words (“hence”, “therefore”, “since”, and so on) or and inferential relation among the statements. ******
• Arguments can be divided into two groups: deductive and inductive. A deductive argument is an argument in which the premises are claimed to support the conclusion in such a way that it is impossible for the premises to be true and the conclusion false. In such an argument the conclusion is claimed to follow necessarily from the premises. On the other hand, an inductive argument is an argument in which the premises are claimed to support the conclusion in such a way that it is improbable that the premises be true and the conclusion false. In these arguments the conclusion is claimed to follow only probably from the premises. Thus, deductive arguments are those that involve necessary reasoning, and inductive arguments are those that involve probabilistic reasoning.
6、命题的分类： 1）模态命题（必然，可能，必须、禁止） 非模态命题 2）简单命题：性质命题、关系命题； 复合命题：联言命题、选言命题、假言命 题、负命题 A simple statement (or “atomic proposition”) is one that does not contain any another statement as a component. A compound statement (or “compound proposition”) is one that contains at least one simple statement as a component. ******
二、推理Arguments /inference
1）所有贪污罪都是故意罪，所以有的故意罪是 贪污罪。 2）公务员要通过普通话等级考试，我将来要当 公务员，所以我必须要通过普通话等级考试。 3）只有这只鸡蛋是受精卵，才能孵出小鸡；这 只蛋不是受精卵，因此孵不出小鸡。 4）希特勒是纸老虎，墨索里尼是纸老虎，东条 英机是纸老虎，所以反动派都纸老虎。 5）声和光都是直线传播，有反射和干挠，声音 是呈波动状态的，即声波，所以，光也可能 有呈波动状态的属性，存在光波。******
5、推理的种类： 1）直接推理和间接推理（前提的多少） Immediate/direct inference indirect inference 2）演绎和归纳（类比）推理（思维进程的方 向） Deduction and Induction 3） 必然性和或然性推理（前提与结论联系的 性质） necessary reasoning， probabilistic reasoning ******
• Arguments are customarily divided into deductive and inductive. Deductive arguments are those in which the conclusion is claimed to follow necessarily from the premises, while inductive arguments are those in which the conclusion is claimed to follow only probably from the premises. • The evaluation of arguments involves two steps: evaluating the link between premises and conclusion, and evaluating the truth of the pdition extending back to the time of Aristotle which holds that inductive arguments are those that proceed from the particular to the general, while deductive arguments are those that proceed from the general to the particular. (A particular statement is one that makes a claim about one or more particular members of a class, while a general statement makes a claim about all the members of a class.) As a matter of fact, there are deductive arguments that proceed from the general to the general, from the particular to the particular, and from the particular to the general, as well as from the general to the particular; and there are inductive arguments that do the same. For example:
1) Three is a prime number. Five is a prime number. Seven is a prime number. Therefore, all odd numbers between two and eight are prime numbers. 2) Gabriel is a wolf. Gabriel has a tail. Therefore, Gabriel’s tail is the tail of a wolf. 3) All emeralds previously found have been green. Therefore, the next emerald to be found will be green. ******
Summary
＊＊（2002年B类）64.我国是一个农业大国， 农业是国民经济的基础，减轻农民负担，就是 要保护和调动农民积极性，促进农业、农村经 济和国民经济的发展。如果不注意保护农民利 益，随意向农民乱收费、乱罚款和进行各类摊 派，必将挫伤农民的生产积极性。所以（ ） A．要发展经济，特别是要发展农村基础设 施，就要增加农民负担 B．发展经济与减轻农民负担两者并不矛盾 C．不减轻农民负担，将会影响农村的社会 稳定 D．农民负担问题是农村经济发展的最主要 问题
第四讲 命题与推理概述
一、判断、命题和语句(Judgment, proposition/statement and Sentence) ：
1）中国人是不怕死的。 2）台湾不是一个国家。 3）台湾难道不是中国领土的一部分吗？ 4）Olympic Games is a world-famous games. 5）奥林匹克运动会是闻名世界的运动会。 6）他老了。 7）她漂亮得像一朵花。 *8）请关上门。 *9）祝你新年快乐！ *10）我能用一下你的手机吗？ ******
1.判断：对事物情况有所断定的一种思维形式。 2.逻辑特征：对思维对象有所肯定或否定；或真 或假。 3.命题：是表达判断的语句。The proposition is the expression in words of a judgment. 4.区分命题（判断）：能否区分真假。 A proposition is a sentence that is either true or false. 5.命题与语句：陈述句和反问句是命题，表达判 断； 算命先生的决窍 看见你想起了大海 名落孙山 ******
真题练习
• 【答案】B • 【解析】演绎推理的特征（前提蕴含结 论），假言命题的性质（前后件可同真。 A、C、D前提没有涉及，超出前提；“减 轻农民负担”与“保护和调动农民积极 性，促进农业、农村经济和国民经济的 发展”是必要条件关系，可同真，不矛 盾。