LPL 2.1 lecture

LPL 2.1 lecture - Can you think of a case that would...

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What is an argument? one or more premises conclusion conclusion is said to follow from or be supported by the premises Consider the following argument: All men are mortal. Socrates is a man. So, Socrates is mortal The argument intends to show that Socrates is mortal, so the last sentence is the conclusion. The other two sentences provide support for the claim that Socrates is mortal, so they are the argument’s premises. Two types of arguments: Logically valid – If all the argument’s premises are true, then the conclusion must be true as well. Logically invalid – Even if all the argument’s premises are true, the conclusion my still be false. Compare the following arguments: (1) All men are mortal. Socrates is a man. So, Socrates is mortal (2) All men are mortal. Socrates is mortal. So, Socrates is a man. The first argument is valid because its conclusion necessarily follows from its premises. The second argument, on the other hand, is invalid because its conclusion does not necessarily follow from its premises.
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Unformatted text preview: Can you think of a case that would demonstrate that the second argument is invalid? Sound and Unsound arguments: An argument is said to be sound if it is valid and all of its premises are true . Consider the following arguments: (1) All men are mortal. Socrates is a man. So, Socrates is mortal. (2) All rich actors are good actors. Brad Pitt is a rich actor. So, Brad Pitt must be a good actor. What about this one: (3) All rich actors are good actors. Brad Pitt is a good actor. So, Brad Pitt is a rich actor. Regardless of the truth value of the premises and conclusion, all invalid arguments are automatically unsound . A note about Fitch format for arguments All men are mortal. Socrates is a man. So, Socrates is mortal. When we begin to analyze arguments we will use the Fitch format to display each argument. In Fitch format, the premises are listed before the horizontal line (called the Fitch bar) and the conclusion is listed below the line....
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LPL 2.1 lecture - Can you think of a case that would...

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