PHI 1101 Lecture Notes - Lecture 2: Deductive Reasoning, Inductive Reasoning, Co-Premise
Chapter 2
Arguments always have two parts, a premise(s) and a conclusion !
The same statement can be a premise in one argument and a conclusion in a second argument !
The two fundamental types of reasoning are deductive demonstration and inductive support !
A deductive argument is used to demonstrate or prove a conclusion, which it does if it is sound !
An argument is sound if it is valid and its premise(s) is true !
An argument is valid if it isn’t possible for its premise(s) to be true and its conclusion to be false !
An inductive argument is used to support rather than to demonstrate a conclusion !
An argument supports a conclusion if it increases the likelihood that the conclusion is true !
Support is a matter of degrees: an argument supports a conclusion to the extent its premise(s)
makes the conclusion likely !
An argument that offers more support for a conclusion is said to be the stronger than one that
offers less support; the latter is said to be weaker that the former !
Some instructors use the word “strong” in an absolute sense to denote inductive arguments
whose premise(s) makes the conclusion more likely than not !
If it doesn’t make sense to think an argument as providing evidence or support for a
contention, it is probably because it is a deductive argument !
Inductive arguments and deductive arguments can have unstated premises !
Whether an argument is deductive or inductive may depend on what the unstated premise is
said to be !
If an argument is written, diagramming it may help you understand it !
Balance of considerations reasoning often involves deductive and inductive elements !
Influence to best explanation is common type of inductive reasoning in which the conclusion
explain the cause of something
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Document Summary
Arguments always have two parts, a premise(s) and a conclusion. The same statement can be a premise in one argument and a conclusion in a second argument. The two fundamental types of reasoning are deductive demonstration and inductive support. A deductive argument is used to demonstrate or prove a conclusion, which it does if it is sound. An argument is sound if it is valid and its premise(s) is true. An argument is valid if it isn"t possible for its premise(s) to be true and its conclusion to be false. An inductive argument is used to support rather than to demonstrate a conclusion. An argument supports a conclusion if it increases the likelihood that the conclusion is true. Support is a matter of degrees: an argument supports a conclusion to the extent its premise(s) makes the conclusion likely.