Question: Is A Tautology Valid?

Is logic always true?

Tags: In logic, an argument can be invalid even if its conclusion is true, and an argument can be valid even if its conclusion is false.

All of the premises are true, and so is the conclusion, but it’s not a valid argument.

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Is a tautology bad?

A tautology is an expression or phrase that says the same thing twice, just in a different way. For this reason, a tautology is usually undesirable, as it can make you sound wordier than you need to be, and make you appear foolish.

Why is a tautology useless for logical argumentation?

An argument requires support for an idea where as a tautology is merely a repetition/rephrasing of an idea. If a tautology was posed as an argument it would be an invalid one because it doesn’t support the idea any further, not because it is logically incorrect.

What do you call a statement that is always true?

Summary: A compound statement that is always true, regardless of the truth value of the individual statements, is defined to be a tautology. We can construct a truth table to determine if a compound statement is a tautology.

What is the opposite of a tautology?

Tautology refers to a redundant use of language, “too many words”. The opposite of that would presumably be “not enough words”, excessive concision, terseness, insufficiency, curtness. 3. Contradiction refers to something going against something else.

What is the paradox?

A paradox, also known as an antinomy, is a logically self-contradictory statement or a statement that runs contrary to one’s expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically unacceptable conclusion.

What is it called when you use 2 words that mean the same thing?

If two words are synonymous, they mean the same thing. … In addition to describing words with the same or similar meanings, you can use the adjective synonymous to describe things that are similar in a more figurative way.

What are examples of red herring?

This fallacy consists in diverting attention from the real issue by focusing instead on an issue having only a surface relevance to the first. Examples: Son: “Wow, Dad, it’s really hard to make a living on my salary.” Father: “Consider yourself lucky, son.

Are definitions always true?

Thus definitions (being only parts of such propositions) are not true or false.

Why is tautology used?

Essentially, a tautology expresses the same thing, idea, or saying repeatedly. There are many reasons people use tautology in both everyday discussion and poetry, research papers, prose, and song lyrics. … Tautology can demonstrate derision, be used a poetic or literary device, or contain psychological significance.

What does trivially true mean?

The term is also often used for statements that are ‘right for the wrong reasons’ in mathematics proper: whereas ‘ 2+x=4, therefore x=2 ‘ is true, ‘ 2+2=x, therefore 4=4 ‘ is trivially true.

How do you know if a statement is a tautology?

If you are given any statement or argument, you can determine if it is a tautology by constructing a truth table for the statement and looking at the final column in the truth table. If all of the truth values in the final column are true, then the statement is a tautology.

What is a tautological argument?

A tautological argument is an example of circular argumentation. The premise and the conclusion are one and the same. The argument appears as in the form of both a proposition and its logical conclusion that is one and the same.

What makes a tautology?

A tautology is a logical statement in which the conclusion is equivalent to the premise. More colloquially, it is formula in propositional calculus which is always true (Simpson 1992, p.

Why is tautology wrong?

The standard criticism of tautologies goes like this: because of the the fact that tautologies are necessarily true, they do not tell us anything new about the world. They cannot possibly be wrong; therefore, they do not add to our knowledge. They are redundancies, and they ultimately do not need to be stated.

How do you get rid of tautology?

In order to avoid using tautologies, pay careful attention to the logic of what you are writing….How to Avoid TautologyRe-read and spot tautologies.Delete them, or.Change them to phrases that actually add some information to the first.

Is a tautology a valid argument?

If the premises of a propositionally valid argument are tautologies, then its conclusion must be a tautology as well. If the premises of the argument are tautologies, then they are all true under every assignment of truth values to the sentence letters. A valid argument with true premises has a true conclusion.

What is an example of tautology?

In grammatical terms, a tautology is when you use different words to repeat the same idea. For example, the phrase, “It was adequate enough,” is a tautology. The words adequate and enough are two words that convey the same meaning.

What does V mean in truth tables?

~X is true when X is false, and false when X is true. ” v” means “or”. ( X v Y) is true when X is true (no matter what Y is). It is also true when Y is true (no matter what X is). The only way it is false is if *both* X *and* Y are false. ”

What is the difference between tautology and pleonasm?

Pleonasm has a sense of using an unnecessary overabundance of redundant words in one description. Tautology has a sense of saying the exact same in different words, using multiple words with the same meaning.

Is math a tautology?

Mathematics is one big tautology — there’s no escaping that. If you imagine MATH as a person, and you were to state any theorem to MATH, MATH would say “well obviously.”