Lecture 1: Recognizing and reconstructing arguments

What is an Argument?

An argument is a set of statements, one of which is intended as the conclusion and the others are intended as premises. The premises are intended to provide reason to believe the conclusion to be true.

Examples: Roger Maris’s record of 61 home runs in a single season stood from 1961 until So Roger Maris should be admitted into the Baseball Hall of Fame. I think. Therefore, I am. Selfish men cannot be happy, for they are ever envious. This feather is light in the sense of being non-heavy. Nothing that is light can at the same time be dark. It follows that this feather can’t be dark.

Identifying Arguments

A conclusion indicator signals that the sentence in which it occurs, or that immediately follows it, is intended as a conclusion and the preceding sentences as premises. “[P]remise indicators… signal that the sentence to which they are prefixed is a premise” (Nolt, Rohatyn, and Varzi 2011, 3).

Roger Maris’s record of 61 home runs in a single season stood from 1961 until So Roger Maris should be admitted into the Baseball Hall of Fame. I think. Therefore, I am. Selfish men cannot be happy, for they are ever envious. This feather is light in the sense of being non-heavy. Nothing that is light can at the same time be dark. It follows that this feather can’t be dark.

Standard Format Circle the inference indicators, Bracket and number the premises and the conclusion, Re-write the argument, giving each premise and conclusion its own line and placing the symbol ‘∴’ (or ‘∵’) to the left of the conclusion.

Examples: Obama is a better leader than Bush ever was, as he has the support of more sectors of the population and is well-respected by leaders overseas. I’ve met a few philosophers in my time and they’ve always been strange people, heads in the clouds, not really in touch with the real world. Philosophers are odd, unworldly people. The Government should regulate the sale of spray paint. Spray paint can be used for tagging and tagging causes damage to private property. The sale of anything that causes damage to private property should be regulated.

1[Obama is a better leader than Bush ever was], as 2[he has the support of more sectors of the population] and 3[is well-respected by leaders overseas]. Obama has the support of more sectors of the population. Obama is well-respected by leaders overseas. ∵ Obama is a better leader than Bush ever was.

1[I’ve met a few philosophers in my time and they’ve always been strange people, heads in the clouds, not really in touch with the real world.] 2[Philosophers are odd, unworldly people.] I’ve met a few philosophers in my time and they’ve always been strange people, heads in the clouds, not really in touch with the real world. ∵ Philosophers are odd, unworldly people.

1[The Government should regulate the sale of spray paint.] I say this because 2[spray paint can be used for tagging and tagging causes damage to private property]. And 3[the sale of anything that causes damage to private property should be regulated]. Spray paint can be used for tagging and tagging causes damage to private property. The sale of anything that causes damage to private property should be regulated. ∴ The government should regulate the sale of spray paint.

Complex Arguments

A complex argument is an argument containing at least one conclusion that is also used as a premise to derive a further conclusion. A nonbasic premise or intermediate conclusion is a statement that functions both as a premise and as a conclusion in a complex argument. A basic premise is a premise that is not also a conclusion.

Example 1[Fido is a dog.] 2[All dogs are mammals], so 3[Fido is a mammal]. And since 4[all mammals are warm blooded], it follows that 5[Fido is warm blooded]. Fido is a dog. All dogs are mammals. ∴ Fido is a mammal. All mammals are warm blooded. ∴ Fido is warm blooded.

1[If the Rangers beat the Pirates tomorrow, then they will make the playoffs]. 2[The Rangers have better hitting and pitching than the Pirates]. 3[If one team has both better hitting and better pitching than its opponent, then this team will beat its opponent]. So 4[the Rangers will beat the Pirates tomorrow]. Therefore, 5[the Rangers will make the playoffs]. If the Rangers beat the Pirates tomorrow, then they will make the playoffs. The rangers have better hitting and pitching than the Pirates. If one team has both better hitting and better pitching than its opponent, then this team will beat its opponent. ∴ The Rangers will beat the Pirates tomorrow. ∴ The Rangers will make the playoffs.