Deductive, Inductive, and Abductive Reasoning (with Examples)

May 29, 2023

Understanding different types of arguments is an important skill for philosophy as it enables us to assess the strength of the conclusions drawn. In this blog post, we’ll explore the characteristics of three different types of argument and look at some examples:

Deductive Arguments: The Conclusion is Certainly True

Deductive arguments operate on the principle of logical necessity, aiming to provide conclusions that follow necessarily from the premises.

These arguments seek to establish the truth of specific claims based on the truth of general principles or premises. Deductive reasoning allows for definitive and conclusive outcomes if the premises are true.

In other words, deductive arguments are logically watertight: If the premises are true, it’s logically impossible for the conclusion to be false.

General Format of a Deductive Argument:
  1. Premise 1: General Principle A is true.
  2. Premise 2: General Principle B is true.
  3. Premise 3: General Principle C is true.
  4. Conclusion: Therefore, Specific Claim X is true.
Example:
  1. Premise 1: All dogs are mammals.
  2. Premise 2: Rex is a dog.
  3. Conclusion: Therefore, Rex is a mammal.

In this deductive argument, the conclusion follows necessarily from the premises. If we accept the truth of the general principle that all dogs are mammals (1) and the premise that Rex is a dog (2), we are logically compelled to accept the conclusion that Rex is a mammal (3).

Other examples of deductive argument formats include modus ponens and modus tollens.

Note: A deductively valid argument means the conclusion necessarily follows from the premises and so, if the premises of the argument are true, the conclusion must also be true. However, the premises may be false, in which case the conclusion may be false too. For example:

  1. Premise 1: If today is Monday, the moon is made of green cheese.
  2. Premise 2: Today is Monday.
  3. Conclusion: Therefore, the moon is made of green cheese.

This argument is still deductively valid – the conclusion does follow necessarily from the premises – but the conclusion is false because one or more of the premises are false. For more detail on valid reasoning (including the difference between a valid and sound argument) see this post.

Inductive Arguments: The Conclusion is Probably True

Inductive arguments involve reasoning from specific instances or observations to general conclusions or generalisations.

They aim to make general claims based on limited evidence, seeking to establish patterns, trends, or probabilities. While inductive arguments do not guarantee absolute certainty, they offer insights and probabilistic reasoning.

In other words, inductive arguments are not logically watertight – but they nevertheless provide support for the conclusion.

General Format of an Inductive Argument:
  1. Premise 1: Observation A is true.
  2. Premise 2: Observation B is true.
  3. Premise 3: Observation C is true.
  4. Conclusion: Therefore, it is likely that Generalisation X is true.
Example:
  1. Premise 1: Every bird I have observed can fly.
  2. Premise 2: The next bird I encounter will likely be able to fly.
  3. Premise 3: The bird species documented so far exhibit the ability to fly.
  4. Conclusion: Therefore, it is probable that all birds can fly.

This example illustrates an inductive argument where the conclusion is based on observed instances and generalises the ability of flight to all birds. While the conclusion is likely to be true, it is possible to encounter a bird species that cannot fly (e.g. an ostrich or a penguin), which weakens the argument’s strength.

Another type of inductive argument is an argument from analogy, where because two things are similar in one way they are likely to be similar in another way. For example, if your friend likes the same music as you, this may suggest they will like the same art as you.

Abductive Arguments: The Conclusion is the Best Explanation

Abductive arguments focus on finding the best or most plausible explanation for a given observation or phenomenon.

They involve reasoning from evidence to a hypothesis or explanation that provides the most likely account of the observed facts. An explanation may be considered more likely or plausible because it fits more neatly with the observed data, for example, or because it is the simplest explanation with the fewest assumptions (a principle known as Ockham’s Razor).

Like inductive arguments, abductive arguments are not logically watertight. Although a hypothesis may seem to be the best explanation, other explanations are still logically possible.

General Format of an Abductive Argument:
  1. Observation: There is a certain observation or phenomenon.
  2. Evidence: Supporting evidence related to the observation.
  3. Hypothesis: A proposed explanation or claim that best accounts for the evidence.
  4. Conclusion: Therefore, Claim X is the most plausible explanation.
Example:
  1. Observation: The grass in the garden is wet.
  2. Evidence: There are water droplets on the leaves, and the ground is damp.
  3. Hypothesis: It rained last night.
  4. Conclusion: Therefore, the wet grass is most likely due to rain.

In this abductive argument, the wet grass and the presence of water droplets on the leaves and damp ground are the observed evidence. The hypothesis that it rained provides the best explanation for the observed evidence. However, other explanations, such as sprinklers or a hose, are also possible.

Applied to A Level Philosophy

There are various examples of deductive arguments, inductive arguments, and abductive arguments in A level philosophy.

Examples of deductive arguments in A level philosophy:
Examples of inductive arguments in A level philosophy:
Examples of abductive arguments in A level philosophy:

Identifying whether an argument is deductive, inductive, or abductive is a great way to demonstrate detailed and precise knowledge of philosophy and pick up those AO1 marks.

Further, knowing the difference between these types of arguments can also be useful to help evaluate (AO2) the strengths and weaknesses of the various arguments you consider in the 25 mark essay questions.

The philosophy textbook written with the student in mind!