Here is the last episode of our summer philosa series (*)
Imagine that you see an animal in the distance and that you say to yourself: "Here, there is a dog there."How does the mind work to arrive at this assertion?The animal has four legs and a head, and yet you do not say that it is a goat or a boar.But what makes you say when he is a dog?Not its size, there are small dogs like a fox and others big as a calf.Not his coat, there are hairy dogs like a deer and other decks like a sheep.Not its color, not its size ... But what is dog specific then?The barking, yes, okay.But, in our thought experience, the dog is too far so that we can hear it.And yet, you say to yourself: "Here, there is a dog there."
There is only one possible explanation: in us there is a category called "dog".Faced with a known or unknown object, faced with a precise or blurred image, the mind cannot help closing what it perceives and bringing it closer to what it knows.It can be a dog, but it would go exactly the same in front of a screwdriver, a banker, a cheese or a suitcase.The perception of the world supposes the a priori existence of mental categories.
But where do they come from, these categories?How do they appear?At what age ?How do they relate to each other?The list of questions is long.The "categories" bring us back in any case to Plato who considered it to be able to do without it and to Aristotle who made him one of the pillars of his thought system.
Aristotle started from an observation: the verb "being" can be used in a very different way.We realize this by comparing small sentences as we are five, we are Thursday, we are in Antwerp, we are in a hurry, we are human beings or, more simply, we are.Even if these six sentences can characterize the same situation with the same word, the verb to be given there each time in a different way because it refers respectively to quantity, space, time, quality, to the'essence or existence.
A two -step engine
The categories are essential for thought, but they nevertheless have two characteristics to pay attention.
A category always has an arbitrary, imprecise, subjective and conventional side.It is therefore never true or false, and the only way to appreciate it is to see its usefulness.For a supermarket manager wishing to increase its turnover, the category of young dads would bring together as many people as that of young mothers, but it would probably be less useful.
The categories are rigid and frozen in a world that is not.So one day or another they become unsuitable, and they must then give way to new categories.In the sixties, IBM was thus a member of the Belgian employers' federation of… metal constructions!Upon arrival of the computer manufacturer, as the adequate category did not exist, nothing better than putting American computers in the company of the Hauts Fourneaux, barbed wire and rolling mills.
Despite these big disabilities, the invention of the "category" by Aristotle is a decisive moment in the history of thought, because it has then become possible to understand - a little - and to model the way in which we reason.
As the diagram shows, thought is a two -step engine, constantly in motion between, on the one hand, a diverse, complex, blurred and uncertain reality and, on the other hand, our categories and other rigid generalizations, stereotypical, even caricatural.Thinking consists mainly of simplifying what is in front of us, and using these simplifications.The symmetry, which a too fast glance could have observed in the model, therefore does not exist.Essentially, everything differentiates the two times from thought.The one of the top is "induction".It leads, from certain particular elements, to general hypotheses.The one at the bottom is "deduction".It leads, from accepted premises as they are necessary.
To go on vacation we induce an idea, and then we deduce the best way to organize.
Reason in all directions
The syllogism also invented by Aristotle makes people who want to model thought today, and yet its usefulness remains formidable.The proof is that it allows us to clarify and develop our words.
Take the same three little sentences, but organize them in three different sequences.
A. All the houses on this street are Beauxb.This house is in this rueC.This house is beautiful
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B. This house is in this rueC.This house is Bellea.All the houses on this street are beautiful
C. This house is Bellea.All the houses on this street are Beauxb.This house is on this street
These three reasoning sheds light on three very different ways of thinking.
The first reasoning starts from the general and goes to the individual.If it respects the rules of logic, it will be correct.A deduction can be imagined perfect, and if you start it again, it will provide the same result.But the weak point of the deduction is obviously its starting point.Boited or false hypotheses, we can indeed deduce anything.A correct deduction is not enough to assert that the conclusion is true.
The deductive reasoning is the easiest and, one day or another, they will all be provided by machines.
No algorithm available
The second reasoning starts from the individual and goes to the general.
The reflection is built on observations and leads to one or the other hypothesis which one cannot be 100 %sure.Perfect induction is impossible because it would take infinite time.There is no available algorithm, at most heuristics, "ways of finding", whose reliability cannot be total.
An induction necessarily supposes a letting go, a shortcut, a form of challenge, because it is not rational to be 100 % rational.Someone who would require being able to study all possible vacation projects would never go on vacation.In induction, errors are always possible.
Induction goes from individual to universal, it is through her that scientific theories are developed.The deduction goes from the universal to the particular, it is through it that scientific theories are tested.
The deduction is a form of simple reasoning.Its starting point is taken as is, without taking into account all the difficulties that have dotted its development.A deduction is logically concluded, necessarily from a few concepts.If I have an idea of what a "budget" and a "balance" in me, I can deduce an opinion about the one that I am offered for next year.
The starting point for induction, however, is the set of observations I can make.An inductive reasoning begins with an infinity of premises and cannot be purely logical.The deduction starts from concepts, induction is conceptualization itself in action.
Habits from experience
It is not surprising that the "problem of induction" is considered a great problem of philosophy.This is the challenge of generalization, from the passage of the object to the subject.It is in filigrane many questions, for example:
- Because this has always been the case, will that still be the case?
- Can statistics lead to certainties?
- Can habits from experience found the laws of nature?
The third reasoning goes from the particular to the particular.The American philosopher Pierce introduced the idea of abduction to define this second particular form of very common non -deductive reasoning.From a simple premise, I induce another simple hypothesis.
The idea of abduction highlights in humans a very frequent, even necessary mental activity, which guides our behaviors without being formally valid.She underscores all the suggestions received on the Internet without surprise.You liked X, so you will like it!Indeed, from individual to individual ...
(*) At the origins of Western philosophy
2,400 years ago, under the Mediterranean sun, Plato and Aristotle meet with what will be one of the most important meetings in history.Their philosophical controversy is still useful to think about our current world.In the company of the philosopher Luc de Brabandere, the free part this summer to meet them which is at the origin of Western philosophy.Find all the episodes of this series below.With Anne Mikolajczak and the illustrator Rif (Cartonbase), Luc de Brabandere will publish in November "Plato vs Aristotle, a joyful initiation to the philosophical controversy" by Éditions Humaines, a work from which this series is taken.
