What other types of reasoning are there?

What other types of reasoning are there?


Deductive and inductive reasoning are based on logical arguments. They involve us examining wide-ranging principles and rules: in the case of deduction going from those wide-ranging principles and rules (and reaching a conclusion about a specific case), and in the case of induction, reaching a conclusion those wide-ranging principles and rules (going from a specific case).
Life often makes it impractical to draw on such wide ranging principles, since don’t often have time to do so. If we want to buy a good sandwich, for example, we have to make a snap decision, since our lunch breaks, unfortunately, don’t last for very long. And the way we make that snap decision will almost certainly involve analogical reasoning – the most common form of reasoning there is.
There are two steps to analogical reasoning:

  1. Recognizing that two or more things have one characteristic in common
  2. Assuming that if they have one characteristic in common, they will also have others in common

Putting this in the context of our very important decision about where to buy a sandwich, we may see a sandwich shop with a recognizable name. Although we have never bought a sandwich from that particular shop, we have bought sandwiches from the same franchise in another town. So we conclude that the sandwiches in this one will be as good as the sandwiches we have eaten before from a similar shop.
There are a vast range of examples of analogical reasoning. Analogical reasoning helps scientists to formulate hypotheses, which then go on to be tested. For example, they may observe how one animal behaves in a certain situation, and then propose that other similar animals behave in the same way if presented with the same situation – which they would then go on to investigate. For doctors, they prescribe drugs for illnesses that they have observed being effective in other patients suffering from the same problem. For us as IB students, we practice examination questions in preparation for the finals based on past papers.

Hypothetico-deductive reasoning

So our scientist has come up with a hypothesis. Perhaps he arrived at it by using analogical reasoning, creative reasoning, or perhaps he got there by accident (many of the greatest discoveries and inventions in history were made by mistake – see the section on natural sciences). His next step is to see if his idea works. To figure this out, he will use hypothetico-deductive reasoning (a bit of a mouthful, but the meaning is fairly straightforward). This involves testing his hypothesis by carrying out experiments. If the experiment works, his hypothesis is strengthened, and he will go on to do further, more demanding experiments. If it does not, then he must re-formulate his ideas, and start again.
Hypothetico-deductive reasoning isn’t limited to the world of science, though. We are constantly formulating ideas and then applying them to everyday situations. If the ideas work, we adopt them; if they do not, we discard them.


Classification is a form of reasoning that groups concepts, ideas, and objects together into related categories, and gives them a collective term. We have already used it in order to better understand emotion, but perhaps without understanding why.
We have already used classification in order to understand emotion, but perhaps we haven’t really grasped why. Classification enables us to grasp concepts and ranges of knowledge that are either too wide for us to properly comprehend, or are very hard to clearly outline and describe.
The best example of this is the natural world. How can we possibly have an organized understanding of the whole of existence? One of the first thinkers to try to arrive at an approachable understanding of nature was Aristotle (4th century BC). He ordered the world into living and non-living; then further ordered creatures according to whether they had blood or (according to him) no blood. Although this was a remarkable achievement for its time, his groupings were still very broad.
The most famous classifier in history was Carl Linnaeus (1707-1778). He ordered the living world into kingdoms, phyla, classes, orders, families, genera, and species. Linnaeus had to use impressive powers of reasoning to make his classification system work, since he first had to decide what the different categories should be based on. Should it be size? Appearance? Density? Behaviour? Colour? Such decisions had to be taken based on every single life form known to exist at that time, and still allow the system to work effectively.
Again, classification isn’t just the preserve of scientists. In almost every aspect of life, we use it to help us order our understanding of things. Every time you download a song and save it on your iPod, you do so according to the system of classification you have personally formulated – playlist, song length, album, or genre.

Creative reasoning

Creative reasoning is the type of reasoning that leads people to think ‘outside the box’. It is very unlike deductive reasoning, in which strict rules must be adhered to; instead, creative reasoning specifically demands that you disregard the rules of logic, and try to think without being restricted by any kind of boundaries.
This type of reasoning can be very productive since problems and puzzles in life often don’t conform to logic either. So their solution needs to be figured out by using unpredictable means. Here are some examples of questions that require you to ‘think laterally’ – another phrase that means the same as creative reasoning.

1. The man who hanged himself

Not far from Lisbon, there is a large wooden barn. The barn is completely empty except for a dead man hanging from the middle of the central rafter. The rope around his neck is ten feet long and his feet are three feet off the ground. The nearest wall is twenty feet away from the man. It is not possible to climb up the walls or along the rafters. The man hanged himself. How did he do it?

2. Death in a field

A man is lying dead in a field. Next to him there is a large, unopened package. There is no other creature in the field. How did he die?

3. Anthony and Cleopatra

Anthony and Cleopatra are lying dead on the floor of a villa in Egypt. Nearby is a broken bowl. There is no mark on either of their bodies and they were not poisoned. How did they die?

4. The coal, carrot and scarf

Five pieces of coal, a carrot and a scarf are lying on the lawn. Nobody put them on the lawn, but there is a perfectly logical reason why they should be there. What is it?

5. Playing chess

Two boys were playing chess. They played five games, but they both won the same number of games, and there were no drawn games. How can this be?

6. Swimmer in the forest (an ‘urban myth true story’)

Deep in the forest was found the body of a man who was wearing only swimming trunks, snorkel and face mask.

(1. He stood on a block of ice; 2. He jumped out of a plane with a parachute on; 3. Anthony and Cleopatra are goldfish; 4. They were on a snowman; 5. They were playing separately; 6. He was scooped up by a fire-service aircraft whilst swimming and deposited on a forest fire)


Cite this page as: Dunn, Michael. What other types of reasoning are there? (10th May 2013). theoryofknowledge.net. http://www.theoryofknowledge.net/ways-of-knowing/reason/what-other-types-of-reasoning-are-there/ Last accessed: 22nd January 2017


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