Propositions – Propositions are statements which constitute the basic element in reasoning. Their distinctive character is that they assert that something is the case or that something is not the case. Their assertion may be true or false. Propositions are therefore statements that have a truth-value, that is, they have the property of being true or false.
Logic is the study of the principles of correct reasoning.
Being a president is like riding a tiger.
Charles Dickens wrote Romeo and Juliet.
Propositions differ from question, commands, and examinations. Only propositions can be either affirmed or denied. Questions may be asked, commands given, and exclamations uttered, but none of them can be affirmed or denied, or judged to be either true or false.
Argument – Argument is a group of statements, one of which is claimed to follow from the others.
1.) An argument consists of at least two statements, one that is claimed to follow, called the conclusion, and at least one another, called the premise, that is claimed to support the conclusion.
2.)Every argument involves at least one inference – the inference from the premise to the conclusion.
3.) An argument involves a claim that one statement follows from the others, that is an argument purports to show that something is true.
An argument therefore is not a mere collection of propositions but contains a premise-conclusion structure. The simplest kind of argument consists of just one premise and a conclusion. Here is an example in which each is stated in a separate sentence:
The investigation of supernatural phenomena lies outside the realm of science. Therefore science can neither prove nor disprove the existence of God.
In the above example the premise is stated first and the conclusion second. But the order in which they are stated is not significant from the point of view of logic. An argument in which the conclusion is stated in the first sentence and the premise in the second is shown by the following example.
Moreover, cutting social security will not improve the deficit problem. As the chairman of the National Economic Development Authority has noted, social security is funded by separate payroll taxes and contributes not a cent to the deficit.
In some arguments the premise and the conclusion are stated in the same proposition. Following is an example of a one-sentence argument whose premise precedes its conclusion.
The solar system is much younger than the universe (only 4.5 billion years compared with 10 to 15 billion years), and so it must have formed from older matter that had a previous history.
Sometimes the conclusion precedes the premise in a one-sentence argument, as in the following example.
The budget deficit will not be brought under control because to do so would require our elected leaders in Congress to do the unthinkable – act courageously and responsibly.
As a general rule, when someone gives reasons to support a point of view, that person is usually offering an argument. Likewise when reasons are offered in an effort to persuade us to perform a specified action, we are presented with what is in effect an argument even though the conclusion may be expressed as an imperative or command.
Wisdom is the principal thing; therefore seek the pursuit of wisdom.
Neither a borrower nor a lender be; For loan oft loses itself and a friend.
An argument is good if the conclusion follows from the premises while an argument is bad if the conclusion does not really follow although it is intended to.
Identical twins who inherit the same genes have different intelligence quotient. Environment must play a role in determining intelligence.
A comet appeared and the locusts came. There must be a connection between the appearance of a comet and the coming of the locusts.
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