What is an inference
An inference is a logical reasoning in which a conclusion is reached from one or more premises. Inference is the main object of study of logic, but its importance goes beyond academic thought. In this we will describe the true concept of types of inference
For many thinkers and philosophers, inference is also the core of human thought, of understanding what we read and the way we explain and interpret the world.
And that’s because we make inferences all the time, and it’s not just an attribute of characters like Sherlock Holmes. We infer and draw conclusions from the time we get up until we go to bed. We use our experience, what we know, to reach new conclusions.
For example: you arrive from school, you see your father’s coat on the back of a chair and you conclude that your father has already arrived from work.
If your father’s coat is in the living room, your father is already at home. That is an everyday inference.
Inference Features
Premises and conclusion
An inference is made up of one or more premises and a conclusion, which may follow directly from the premises or arise as new information. For example:
Premises :
- Every time there are clouds over the mountain, it rains in the city;
- Today there are clouds over the mountain;
Conclusion :
- It will surely rain.
Validity and invalidity
Inferences can be valid or invalid. They are invalid when the conclusion has nothing to do with the premises.
For example: “all the dogs I see have tails, therefore dogs can swim”. This inference is invalid because the conclusion has nothing to do with the premise.
True or false
Reasoning or inferences can be logical and valid without necessarily being true. For example: “Juan is Argentine and has an Italian surname; José is Argentine and also has an Italian surname. All Argentines have Italian surnames.
This is an inference whose conclusion is not true. Although if I said “many Argentines have Italian surnames”, it would be a correct conclusion.
It is based on prior knowledge
In inference we use prior knowledge to “infer” or “deduce” something new. We do it all the time, which is why cognitive psychologists like Jerome Bruner (1915-2016) have referred to the human mind as an “inference machine.”
It is a tool for interpreting data.
Inference allows us to interpret information obtained through interviews, surveys or inventories. For example: if 40% of a community cannot read, it may not be convenient to carry out a campaign with written brochures and it is better to use audiovisual information.
Hypothesis and inference
When an explanation is proposed from a set of data, a hypothesis is being made, but also an inference or conjecture, which may or may not be confirmed through the tools of the scientific method (experiments, inventories, studies, etc.).
Types of inference
Types of inference can be deductive, inductive, abductive and those obtained by statistical reasoning.
Inferences by deduction
It is an argument that goes from general knowledge and reaches a particular conclusion, as in the famous syllogism that has Socrates as the protagonist:
- All men are mortal.
- Socrates is a man.
- Socrates is mortal.
Inference by induction
It is when the inference is made by going from particular premises to a general conclusion. For example: “Tuna have gills; sardines have gills; cod also have gills. All fish probably have gills.”
Inference by abduction
It is a reasoning in which after knowing the description of a phenomenon or event, a hypothesis or explanation of it is advanced. For example, when trying to explain a historical fact, or the result of a sports game.
Inference by statistical reasoning
They are those that are made from information obtained through surveys, censuses, inventories or electoral processes. The conclusions are drawn taking into account the percentages. For example: if 30% say they will vote for the yellow party and 48% say they will vote for the green party, it is very likely that the latter will win.
Inference techniques
Syllogism
The classic method of inference is that of the syllogism, a form of reasoning in which a conclusion is reached from several premises, as in the examples used in inductive and deductive differences (“all men are mortal”).
Technique in statistical inference
There is also talk of inference techniques in the so-called “statistical inference”, which encompasses a set of methods and techniques to reach conclusions from statistical data.
Statistical inference techniques can be of two kinds: parameter estimation, or hypothesis testing.
In the first, a parameter is taken, a piece of data that is repeated in the information collected, and a value is assigned to it. In the second, the data is contrasted with several hypotheses, until the one that is closest to the information is obtained.
Inference Examples
- There is a group of municipal workers breaking up the street, that means that soon we are going to run out of water.
- Juan’s son likes cookies, my children also like cookies. All children probably like cookies.
- Do all birds lay eggs. The penguin lays eggs. The penguin is a bird.
- The survey found that 70% of people want cleaner air. Environmental policies must be improved.
- In the world, 97% of climate scientists believe that global warming is caused by humans. So it is most likely true.
- When she was murdered, her husband was in a meeting at the office, so we can rule out that he was the one who killed her, at least not directly.
- If the sun rises in the east every day, it is certain that tomorrow it will too.
- Eduardo and his parents have dark brown hair; his girlfriend Laura and his parents also have dark brown hair; His children are likely to be born with dark brown hair.
- Classes start at eight and it takes me an hour to get to school from home. If I don’t get up before seven, I’ll probably be late.
- If I save half my allowance each day, I may be able to buy a bicycle by the end of the year.
