An introduction to the logical structure of arguments

How do you know if you should trust the expert? The following argument is based upon research published in a peer-reviewed medical journal.

An introduction to the logical structure of arguments

This kind of logical relation is called an entailment. An entailment is a logical relation between or among propositions such that the truth of one proposition is determined by the truth of another proposition or other propositions, and this determination is a function solely of the meaning and syntax of the propositions concerned.

Another way to remember the difference between an inference and an entailment is to note that people infer something, and propositions entail something.

The argument structure is the sum and substance of logic.

An introduction to the logical structure of arguments

All that remain in this course is to sketch out a bit of what this means. We have spoken earlier of the relation between or among propositions.

What is a proposition or statement we will use these words interchangeably? Hence logic is just concerned with those statements that have truth-values. There is very much of life that is irrelevant to logic.

Consider the confusion that would result if we considered the following sentences as statements: Then, if ever, come perfect days Thus, phatic communication, greetings, commands, requests, and poetry, among other uses of language, are not mean to be taken as statements.

Which of the following sentences are statements? There is iron ore on the other side of Pluto. Tomorrow, it will rain. Open the door, please. You should vote in all important elections. More distinctions with regard to statements are worth suggesting. Consider whether there are two statements in the box: A Republican is President of the U.

Aside from the ambiguity of when the statements are uttered, of which President is being spoken, and so on, we would say that there is one statement and two sentences in the box. Sometimes logicians make a distinction between a sentence token the ink, chalk marks, or pixels and a sentence type the meaning of the marks.

Every statement comes with an implicit time, place, and reference. Summary of the distinction between a sentence and a statement assumes that adequate synonymy of expression and translation between languages is possible. One statement can be expressed by two different sentences.

A sentence can express different statements at different times. A statement is independent of the language in which it is asserted, but a sentence is specific to the language in which it is expressed.

A sentence can express an argument composed of several statements. Normally, the sentence would be considered as being composed of two premises and a conclusion. Thus, this sentence would be composed of three statements.Thus structure of an argument consists of propositions of different two types - premise and conclusion, in which the the truth of the conclusion is supposed to follow from the truth of premises based on the inferential connection between the two.

For example look at the argument consisting of following argument. Earth is a planet. A logical argument, seen as an ordered set of sentences, has a logical form that derives from the form of its constituent sentences; the logical form of an argument is sometimes called argument form.

Some authors only define logical form with respect to whole arguments, as the schemata or inferential structure of the argument. Essay Structure Writing an academic essay means fashioning a coherent set of ideas into an argument.

Because essays are essentially linear—they offer one idea at a time—they must present their ideas in the order that makes most sense to a reader. In this logic the validity of deductive arguments depends only on the logical structure of the sentences involved.

This development in deductive logic spurred some logicians to attempt to apply a similar approach to inductive reasoning. A formal logical fallacy means that the argument is invalid, due to a flaw in its logical structure, which also means that it’s unsound.

An informal logical fallacy means that the argument is unsound, due to a flaw in its premises, though it can still have a valid logical structure. Philosophy Introduction to Logic Diagramming Arguments. Abstract: Analyzing the structure of arguments is clarified by representing the logical relations in diagram form.

Arguments in logic are composed reasons being offered for a conclusion.

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