Western Logic Fallacies of Defective Induction Informal Fallacy

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Western Logic Informal Fallacy: Fallacies of Defective Induction (Philosophy)

Fallacies of Defective Induction

  • These fallacies occur because although the premises of the argument seem strong and relevant to the conclusion but in reality, they are weak and ineffective, so relying on a conclusion drawn from them is a mistake.
  • The fallacies of Defective Induction are of four types;
    • The argument from ignorance
    • The appeal to Inappropriate authority
    • False Cause
    • Hasty Generalisation

The Argument from Ignorance

  • Argument from ignorance is a fallacy which arises when we take something to be true because we do not know for sure whether or not it is false.
  • For example, unicorns must exist because no one is sure that they do not exist.
  • Similarly, we take something to be false which has yet not been proven true.
  • It is also called Argument ad Ignorantiam.

The appeal to inappropriate authority:

  • Appeal to authority occurs when we insist that a claim is true simply because a person of authority has said it to be true.
  • For example, Richard Dawkins, an evolutionary biologist says the evolution is true. Therefore, it must be true.
  • On the other hand, the fallacy of Appeal to Inappropriate Authority occurs when an appeal is made to an authority which has no special claim to expertise on the matters in question.
  • Example would be, asking Picasso (painter) to solve the mathematical numerical.
  • Argument ad Verecundiam is also known as appeal to inappropriate authority.

The False Cause

  • The fallacy of false Cause occurs when the cause of an event accepted is not really its cause.
  • Eg. it must have rained as my pots are all full. False cause is rain. It did not rain, my pots are filled by my mother.
  • In other words, false cause is a fallacy where a thing which is taken to be the cause of the event is actually not its cause.
  • Another example would be, “As soon as the people ate vitamin and mineral tablets, they began to fall ill. we obviously shouldn՚t be taking vitamins and minerals via tablets.”
  • Here, vitamin and mineral tablets are not the cause of people falling ill.
  • The reason or the cause behind people falling ill must have been some other reason.
  • Vitamins and mineral tablets are doctor prescribed.

The Hasty Generalisation

  • Hasty generalisation is a fallacy of defective Induction.
  • In this we take a thing true is true for all things, if it has proven to be true of one thing.
  • Example, my friend from Lucknow likes Parathas. Therefore, all the people from Lucknow like Parathas.
  • It is a fallacy because what is true of one thing need not be true for all the other things.
  • Hasty Generalisation is also called fallacy of converse accident.
  • It is important to note that the fallacy of Hasty Generalisation is the opposite of fallacy of Accident which is a fallacy of presumption.
  • Under the latter, when we apply the generalisation to particular instances.
  • We think what is true for the whole, is also true for the parts.
  • For example, people of North-East India like Thupka. Therefore, my friend from North-East must definitely like Thupka.
  • This fallacy is an opposite of Hasty Generalisation, where we move from particulars to generalisation.
  • Hasty Generalisation is also called fallacy of converse accident.
  • In short, Hasty generalisation or faulty generalisation or hasty Induction occurs when we draw a conclusion based on a small sample. For example,
    • My father smoked cigars
    • My father lived till the age of 92
    • Therefore, smoking is not really injurious to health.
  • This is an example of hasty generalisation which is unreasonable in nature.
  • Unreasonable because it draws a universal conclusion about non-existing health risks of smoking by studying just one person.


1. Fallacies of Defective Induction are ________

A. Formal fallacies

B. Informal fallacies

C. Fallacies of language

D. Both B and C

Answer: B

2. There are ________ types of Fallacies of Defective Induction

A. Three

B. Four

C. Five

D. None

Answer: B

3. Hasty Generalisation is stark opposite to

A. False cause

B. Fallacy of Accident

C. Fallacy of Division

D. Red Herring

Answer: B

4. Hasty generalisation is also known as

A. Fallacy of Accident

B. Fallacy of Converse Accident

C. Fallacy of Division

D. Fallacy of converse Division

Answer: B

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