Unit 3 Reasoning

Learning outcomes

By the end of this unit you should:

  • be able to explain the differences between deductive, inductive and abductive reasoning
  • be aware of causing reasoning
  • be able to explain the 13 concepts in the review section

Argumentation review

Activity 1 Watching

Listen to and watch this review of logical arguments.

Identifying reasoning

Simply put, reasoning can be thought of as the process used to move from evidence to claim, or from premises to conclusion. This course focuses on logical reasoning.

Activity 2 Thinking

List the different types of reasoning that you know. Prepare to explain them to a classmate in English. Rehearse by saying the explanation aloud with to yourself or practice with a classmate.

Activity 3 Watching

Watch this explanation of four types of reasoning.

Activity 4 Watching

Watch this excellent explanation of reasoning.

Activity 5 Listening

Listen to this explanation of terminology to describe statements, premises, cases, arguments and conclusions.

These are some of the main terms mentioned in the explanation.

  • Statements: declarative, imperative (orders), interrogative (questions)
  • Premises: true, false
  • Cases: universal (general), particular (specific)
  • Arguments: valid, invalid
  • Conclusions: sound, unsound, cogent, uncogent

One of the key aspects to remmember is the relationship between reasoning and possible types of conclusions. Conclusions based on deductive reasoning may be sound or unsound. Conclusions based on inductive reasoning may be cogent or uncogent. Conclusions based on abductive reasons will be uncogent.

Activity 6 Thinking

Identify the types of reasoning used in arguments created by the 2020 cohort on the topic of the COVID-19 pandemic.

Note that the premises may be true or false. Tthe argument may be valid or invalid. Conclusions reached using deductive reasoning may be sound or unsound. Conclusions reached using inductive reasoning may be cogent or uncogent. Conclusions reached using abductive reasoning are uncogent.

  1. Patients infected with the COVID-19 have the common symptoms of fever, cough, and shortness of breath. There are also people who do not show the above symptoms but are infected. Therefore, I may also be infected with the COVID-19 although I don't see any symptoms at the moment.
  2. I have a fever and a cough now. Symptoms of patients infected with the COVID-19 include fever, cough, and shortness of breath. Therefore, I am infected with the COVID-19.
  3. I have a fever and a cough now. If I are infected with the COVID-19, I would have a fever and a cough. Therefore, I am infected with the COVID-19.
  4. The use and disinfection of masks are necessary to prevent COVID-19 infection. We want to prevent COVID-19. Therefore, it is important for us to wear a mask and disinfect.
  5. Until now, infection with COVID-19 has caused fever, malaise, and headaches. Therefore, infection with COVID-19 causes these symptoms.
  6. COVID-19 is currently raging around the world. If the initial containment by a government fails, the virus will spread all over the world. Therefore, the government must have failed to contain it.
  7. In all prefectures of the Shikoku region, infected persons with COVID-19 are confirmed. Kagawa prefecture is in the Shikoku region.Therefore, there are infected persons with COVID-19 in Kagawa prefecture.
  8. 193 countries are members of the United Nations. Over 150 countries identified people infected. Therefore, there is no country with no people infected.
  9. The boy has a fever of 37.6 degrees(celsius). If a person is infected with COVID-19, the person would have a fever of about 37.5 degrees(celsius). Therefore, the boy is infected with COVID-19.
  10. Medicine for COVID-19 is necessary for infected people to get well. The medicine for COVID-19 has not yet been created . Therefore, COVID-19-infected people cannot be treated with medicine for COVID-19.
  11. People buy things only when the economy is going well. People are not able to to buy things as well as before the spread of COVID-19. Therefore, the economy is not going well.
  12. When the number of patients is large, doctors and nurses become busy. The spread of COVID-19 increased the number of the patients. Therefore, doctors and nurses are busy.
  13. COVID-19 can kill people. Something kills people is dangerous. Therefore COVID-19 is dangerous.
  14. COVID-19 can kill people. Many people around the world are avoiding infection with COVID-19. Therefore, people do not want to die.
  15. COVID-19 is a kind of virus. We have developed medicines to cure harmful viruses before. Therefore, we will find a way to cure or defeat COVID-19.
  16. COVID-19 is categorised as an envelope virus. Envelope viruses are more susceptible to damage by alcohol disinfection. Therefore, hand washing and alcohol disinfection are effective for prevention of COVID-19.
  17. The person had a fever that lasted about a week. The person was infected with COVID-19. Therefore, when a person develops symptoms of fever for about a week, he or she is infected with COVID-19.
  18. One person’s sense of taste and smell are impaired. If the person had been infected with COVID-19, his or her sense of taste and smell would have been impaired. Therefore, the person is infected with COVID-19.
  19. COVID-19 is transmitted by droplet and contact infections. For this reason, avoiding human contact can be effective in preventing infection.
  20. COVID-19 has not yet established an effective treatment for it. Therefore, if the disease becomes severe, it is high likely to result in death.
  21. COVID-19 is considered not infected if the test is negative. However, there were cases where the test was negative once, but came back positive on retesting. Therefore, we should not completely believe the contents of the test.
  22. All people in that room two weeks ago came down with COVID-19. He was in this room two weeks ago. Therefore, he came down with COVID-19.
  23. For prevention of COVID-19, I went to the supermarket to buy some masks. The masks were sold out at the supermarket. Therefore, the masks were sold out at all supermarkets.
  24. Lecturing online prevents COVID-19 from spreading. If students take lectures online, they would not come down with COVID-19. Therefore, lecturing online prevents COVID-19 spreading.
  25. Coronavirus often causes mild illness. In mild cases, the probability of dying is low. Therefore, the probably of dying from coronavirus is low.
  26. The number people infected with COVID-19 is rising. People get infected by close contact. Therefore, coronavirus is transmitted by close contact.
  27. I have symptoms such as pneumonia. When infected coronavirus, symptoms of pneumonia appear. Therefore, I am infected by coronavirus.
  28. Humans have a possibility of becoming infected with coronavirus. I am a human. Therefore, I have the possibility of becoming infected with coronavirus.
  29. I have ten masks to prevent coronavirus. All the masks are white. Therefore, all masks are white.
  30. Coronavirus is an infection. If some has influenza, they would have an infection. Therefore, coronavirus is related to influenza.
  31. If people get a high fever and develop pneumonia, they have COVID-19. Now, a man has a high fever and developed pneumonia. Therefore, he has COVID-19.
  32. There are many patients infected with COVID-19 in this hospital. All patients have a high fever and developed pneumonia. When people get COVID-19, they have a high fever and develop pneumonia.
  33. A man has a high fever. If people get COVID-19, they get a high fever. A man must have COVID-19.
  34. COVID-19 is a new type of virus. The prevalent disease virus is COVID-19. Therefore, The prevalent disease virus is a new type of virus.
  35. COVID-19 is a new type of virus. The prevalent disease virus is COVID-19. Therefore, The prevalent disease virus is a new type of virus.
  36. I have a thousands of friends who have COVID-19. All the friends are male. Therefore, all infected people are male.
  37. I'm running a fever from the virus now. If we have cover-19, we would get a fever. Therefore, The virus I am carrying is cover-19.
  38. Viruses can be reduced to 1% by washing your hands with running water for 15 seconds. Corona is a virus. Therefore washing your hands is an effective measure against corona.
  39. As a symptom of corona, a fever of 37.5 degrees or higher for four days or more and a cough symptom have been proposed. Many people go on to undergo RPC testing for these conditions.Therefore, it is always corona when such symptoms occur.
  40. Taste disorders are often reported as an initial symptom of corona. Ten corona patients examined by Doctor A had taste symptoms as the initial symptoms. Therefore, Doctor A determined that taste disorders were a definite initial symptom of corona.
  41. A virus infects humans. COVID-19 is a virus. Therefore, COVID-19 infects humans
  42. COVID-19 is a virus. COVID-19 kills people. Therefore, a virus kills people.
  43. COVID-19 spreads in Tokyo. If people who have COVID-19 live in Aizu, COVID-19 spreads in Aizu. Therefore, people who have COVID-19 live in Tokyo.
  44. People with COVID-19 develop a fever of 37.5 degrees. My current body temperature is 36 degrees. Therefore, I have not developed COVID-19.
  45. So far there have been 6 cases of coronaviruses. The incubation period for the six cases of coronavirus was up to two weeks. Therefore, the incubation period for COVID-19 will be up to 2 weeks.
  46. The COVID-19 is prevalent in Japan. If the COVID-19 spreads from person to person, it will infect others. Therefore, infected persons are in contact with a large number of people.
  47. The size of the virus is about 20~300nm in size. COVID-19 is a virus. Therefore, the size of COVID-19 is about 20~300nm.
  48. COVID-19 is a virus. COVID-19 has a lethal capacity. Viruses have the ability to kill.
  49. You can get the COVID-19 if you are near a person who is coughing. If COVID-19 is transmitted by droplet infection, you can get the COVID-19 when you are near a person who is coughing. Therefore, COVID-19 is transmitted by droplet infection.
  50. Infectious diseases are caused by pathogens. COVID-19 is an infectious disease. Therefore, COVID-19 is caused by a pathogen.
  51. About 8500 people were infected with COVID-19 in Japan. About 10% of them recovered. Therefore, about 10% of all infected people in the world will recover
  52. One illness spreads from person to person.If the disease is “COVID-19”, it will be spread from person to person. Therefore, one illness is “COVID-19”.

Extension (not assessed in 2020 but included for reference)

Activity X Reading

Consider this diagram and the relationship between the different types of reasoning.

Although this section is not part of the official syllabus, it is important to understand that reasoning is not limited to deductive, inductive and abductive. Certainly, deductive reasoning and inductive reasoning are the two most commonly referred to types of reasoning.

reasoning network

The different types of reasoning are listed below:

  • deductive: reasoning from universal cases
  • inductive: reasoning from particular cases
  • abductive: reasoning from particular conditional cases
  • causal: reasoning from effect to cause
  • analytic: breaking a general truth down into particular constituent parts
  • synthetic: constructing a generalization from particular facts
  • a priori: reasoning that is not based on sense experience
  • a posteriori: reasong based on sense experience, i.e. empiric

Knowledge and application

Knowledge and application activities are designed to help you activate the key terminology and apply the concepts covered in the course so far. Try to use the terminology and concepts accurately and appropriately.

Activity 7 Writing

Write three arguments related to COVID-19. Each argument must use a different form of reasoning. Avoid using false premises. For each argument, write a short explanation describing the premises, argument, reasoning and conclusion using logical terminology. Submit your work via ELMS.


Make sure you can explain the following 13 concepts in simple English:

  • reasoning: deductive, inductive, abductive and causal
  • validity: valid vs. invalid
  • soundness: sound vs. unsound
  • cogency: cogent vs. uncogent
  • cases: universal vs. particular

Running count: 36 of 108 logical concepts covered so far.