What is an Inference? Types and Main Characteristics

A inference It is a conclusion or opinion that is reached taking into account known evidence or facts. In logic an inference is defined as the process of deriving logical consequences from the assumed premises.

A premise is also defined as a proposition given as true and from which a conclusion is drawn.

In some cases, the inference is not logically derivable from the assumed premises, but has a certain degree of probability relative to these..

The word inference comes from medieval Latin inferentia which means "carry on." This term is often used synonymously with argument.

Inference is a mechanism by which reasoning takes place. These two go hand in hand, and it is essential to follow a proper inference process to ensure the validity of the reasoning..

Contribution of Charles Peirce

Research on inference and arguments was enriched by the work of the philosopher and mathematician Charles Sanders Peirce (1839-1914).

He made significant contributions to the theory and methodology of induction, and discovered a third type of reasoning or inference: abduction..

Thus, Peirce's classification encompassed three essentially different, though not totally independent, types of inferences: deduction, induction, and abduction..

Despite the fact that in the later stages of his life he considered them as three different stages of research rather than different types of inference, this classification still holds..

The 3 types of inference

1- Deduction

Deduction is the process of deriving a conclusion from the given axioms and facts. That is, draw a conclusion based on available knowledge and observations.

The conclusion can be drawn by applying the rule modus ponens. This inference rule states that if both P and P → Q are known to be true, it can be concluded that Q must also be true. Inference by deduction is also known as logical inference.

Example

Axiom: All mammals have mammary glands.
Fact / premise: Whales are mammals.
Bottom Line: Whales have mammary glands.

2- Induction

For its part, induction implies deriving a general rule (also called an axiom) from particular or specific observations..

This type of reasoning is the opposite of deductive. Basically, it means drawing conclusions or inferences from various data, going from the specific to the general. Scientists use inductive reasoning to form hypotheses and theories.

Example

Data:

1. Juan sleeps less than six hours and wakes up tired.
2. Lucia sleeps less than six hours and wakes up tired.
3. Maria sleeps less than six hours and wakes up tired.
4. Carlos sleeps less than six hours and wakes up tired.

Inference: If a person sleeps less than six hours, they wake up tired.

3- Abduction

This type of inference starts from an incomplete set of observations, leading to the most probable explanation possible..

It is based on making and testing hypotheses using the best information available. It often involves making an assumption after observing a phenomenon for which there is no clear explanation..

Example

An example of this is medical diagnoses based on test results. Another example is the decisions of juries in trials, based on the evidence presented to them..

References

1. Inference. (s / f). On Dictionary.com Unabridged. Retrieved on November 27, 2017, from dictionary.com
2. Inference. (2017, November 08). At Merriam Webster.com. Retrieved on November 27, 2017, from merriam-webster.com
3. Iannone, A. P. (2013). Dictionary of World Philosophy. London: Routledge.
4. Bellucci, F. and Pietarinen, A. V. (s / f). Charles Sanders Peirce: Logic. Internet Encyclopedia of Philosophy. Retrieved on November 27, 2017, from iep.utm.edu
5. Kulkarni, P. and Joshi, P. (2015). Artificial intelligence: Building Intelligent Systems. Delhi: PHI Learning.
6. Johnson, G. (2017). Argument and Inference: An Introduction to Inductive Logic. Massachusetts: MIT Press.
7. Velleman, D. J. (2006) How to Prove It: A Structured Approach. New York: Cambridge University Press.
8. Bradford, A. (2017, July 24). Deductive Reasoning vs. Inductive Reasoning
   In Live Science. Retrieved on November 27, 2017, from livescience.com