Critical Thinking Lecture 1 What is Critical Thinking? By David Kelsey

What is Critical Thinking? Critical Thinking is: Thinking about thinking Objective Without Bias Without emotional influence Based on Reason Analysis is crucial

Inferences An inference is: A Deductive inference: A move from one claim to another, the first is taken as reason to believe or evidence for the second A Deductive inference: Occurs when one claim necessarily follows another Examples… An Inductive inference: Occurs when one claim follows another with a high degree of likelihood Examples

Statements Statements: A statement is the same as a Proposition A proposition is the meaning of a sentence So a sentence can have a meaning just like words have meanings

Literal and Intended meaning Literal meaning: The literal meaning of a sentence is the meaning of the words of the sentence on their face. The literal meaning of a sentence is the Proposition that the sentence Expresses. Expression is like tossing meaning in the air so that it can be understood. Intended meaning: The intended meaning of a sentence is the meaning that the speaker or writer of the sentence intends to say. It is the thought the speaker has in mind when speaking or writing the words. We will say that the intended meaning of a sentence is the Proposition the sentence Asserts. Assertion is like declaration.

Sentences and meanings, an example Here is an example of a sentence connecting to its meaning. Consider I say “I am going to the beach right now.” The literal meaning is just ‘it is the case that I am going to the beach right now’. Notice that this is also the intended meaning of my words. But now notice the phrase ‘it is the case that’. So the meaning of my words is true just in case I really am going to the beach right now. So meaning is true and false…

A second example in Sarcasm Now consider that I say about my very messy roommate that “he always takes the trash out.” The literal meaning of my words (the proposition I express with my words) is that he always takes the trash out. What I intend by my words though (the proposition I assert with my words) is that he never takes the trash out.

Arguments An Argument is: For example: A position supported by reasons for its truth A position is a stance on an issue An issue is a Question that can be answered yes or no For example: Consider the issue of whether marijuana should be legalized for recreational use in this country? Say for example I take the position that it shouldn’t be legalized and give as a reason that marijuana use is correlated with psychological disorders…

Three more arguments Consider the issue of whether there is intelligent life in the universe outside of Earth. Consider the issue or whether the Safety Belt law is just. Consider the issue of whether Mac computers are better than PCs.

More on arguments Arguments are composed of conclusions and premises: The conclusion is the position taken The premises are the reasons given Examples… We can find arguments by looking for premise and conclusion indicators: Conclusion indicators include ’Thus’, ‘Therefore’, ‘Hence’ and ‘So’ Premise indicators include ‘Because’, ‘Since’, ‘For’, and ’For example’