What is wrong with my intuition of Modus Tollens?

Why is modus tollens wrong?

If the conclusion is true for each critical row, then the argument form is valid. But if even one of the critical rows contains a false conclusion, the argument is invalid.



Modus Ponens Modus Tollens
Therefore, I will wear my sunglasses. Therefore, it is not bright and sunny today.

Is modus tollens valid?

MT is often referred to also as Denying the Consequent. Second, modus ponens and modus tollens are universally regarded as valid forms of argument.

What is modus tollens with example?

Modus tollens is a valid argument form in propositional calculus in which and are propositions. If implies , and is false, then. is false. Also known as an indirect proof or a proof by contrapositive. For example, if being the king implies having a crown, not having a crown implies not being the king.

How do you construct a modus tollens argument?

Here are how they are constructed:

  1. Modus Ponens: “If A is true, then B is true. A is true. Therefore, B is true.”
  2. Modus Tollens: “If A is true, then B is true. B is not true. Therefore, A is not true.”


What is fallacy of modus tollens?

In instances of modus tollens we assume as premises that p → q is true and q is false. There is only one line of the truth table—the fourth line—which satisfies these two conditions. In this line, p is false. Therefore, in every instance in which p → q is true and q is false, p must also be false.

How do I identify modus tollens?


Example if your king is in checkmate than you've lost the game. You have not lost the game therefore your king is not in checkmate. Sounds reasonable you put in anything for a and B it.

What is modus tollens in philosophy?

Modus-tollens definition



Filters. (philosophy, logic) A valid form of argument in which the consequent of a conditional proposition is denied, thus implying the denial of the antecedent.

What is also known as the You Too fallacy?

Tu quoque” means “you too,” and consists of responding to allegations of wrong doing by saying, in essence, “you do the same thing.” That response may be true, but it doesn’t deny or explain away the alleged wrongdoing. Tu quoque is also known as the “you too” fallacy, and the “two wrongs make a right” fallacy.

How do we avoid fallacies?

Do not:

  1. use false, fabricated, misrepresented, distorted or irrelevant evidence to support arguments or claims.
  2. intentionally use unsupported, misleading, or illogical reasoning.
  3. represent yourself as informed or an “expert” on a subject when you are not.
  4. use irrelevant appeals to divert attention from the issue at hand.

What is an error in reasoning called?

A fallacy is a kind of error in reasoning. The list of fallacies below contains 231 names of the most common fallacies, and it provides brief explanations and examples of each of them. Fallacious arguments should not be persuasive, but they too often are.

What is fallacious reason?

Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim.

What is a non sequitur?

Definition of non sequitur



2 : a statement (such as a response) that does not follow logically from or is not clearly related to anything previously said We were talking about the new restaurant when she threw in some non sequitur about her dog.

What causes poor reasoning?

Reasoning, like the prefrontal cortex, is a primarily human trait that develops late in childhood. Reasoning deficits can arise from various causes. For example, impaired reasoning can be an initial symptom of frontal lobe dementia or the sequelae of frontal lobe stroke or head trauma.

Why do some people have no reasoning skills?

According the Surgeon General, mental disability and mental illness can cause a variety of obstacles, including disturbances of thought and perception or cognitive dysfunction. As a result, individuals suffering from such issues may be at an intellectual disadvantage.

What does low abstract reasoning mean?

A candidate who obtains a very low Abstract Reasoning score may struggle to see the ‘big picture’, conceptualise complex problems, detect relationships between ideas, or learn new skills quickly.