Vincent Le Biez: "Are prejudices necessarily bad?"

Former student of the École Polytechnique and the Paris Mines School, Vincent Le Biez is a senior official at the Ministry of Economy and Finance.Passionate about philosophy, he published a remarkable essay where he brings together science and political philosophy "Plato has an appointment with Darwin" (ed.Les Belles Lettres, 2021).

The fight against prejudices is undoubtedly part of the mantras of the time.Prejudices on origin, gender, sexual orientation, social class, age, physical appearance ..., preconceived ideas on many topical subjects, our judgments would invariably altered by a priori questionable andarbitrary, which would deeply harm democratic conversation.

The prejudice would make us both guilty and victim: guilty not to adopt a truly rational approach and to be guided by our emotions and our fantasies, victim of a kind of cunning that would bypass our reason by modifying our perception of reality.

The controversies on the "feeling of insecurity" illustrate this perfectly: there would be an objective truth on the one hand, based on undeniable statistics, and on the other a fantasized reality, resulting from the a priori of individuals and representationsdeceptive conveyed by certain media or political leaders.After Lionel Jospin during the 2002 campaign, it was the Keeper of the Seals who brought up to date this concept, based on statistics that show a marked drop in homicides in France in recent decades.

Beyond this particular case, less simple than it seems so much insecurity and its perception can take various forms which are difficult to reduce to one and the same indicator, the main idea, dear to our societiesmodern, is to flush out and then deconstruct our prejudices in order to achieve a real understanding of the objective reality of the world around us.

To paraphrase the French philosopher and historian Hippolyte Taine, would he, in our modern societies "a prejudice against prejudices"?Is this opposition between the subjectivity of prejudices and the objectivity of statistics so solid as that, from a strict rational point of view?

To question this point of view, it is good to take an interest in an important mode of acquisition of knowledge in science, which is called Bayesian inference.Thomas Bayes is an English mathematician from the 18th century known for a famous probabilities theorem which links in particular the probability that a model is correct given certain observations to the probability of making certain observations if the model is correct.

Bayesian inference, which follows, is an iterative process consisting in looking for the causes of a phenomenon from successive observations.We start from a a priori design or model, a sort of prejudice, for example "this coin is balanced" (that is to say, it has a chance in two to fall on eachface).Then we carry out experiments to collect observations, in this case the number of times the room falls on battery or on face.These observations reinforce or weaken the likelihood of its a priori model.At first, this likelihood is indefinite because we have not yet obtained experience of experience.If after 100 throws, we obtain about 50 batteries and 50 faces, then the likelihood of its initial prejudice will be strongly increased.Conversely, if you get 70 batteries and 30 faces, it will be considerably reduced and we will then be encouraged to update its model: "This coin is unbalanced in favor of battery".

When you do not have large series of reliable statistics, Bayesian inference is undoubtedly the most rational approach that is.It is explicitly or implicitly used by all scientists.It is interesting to note that in this approach, prejudices are not rejected immediately but are on the contrary used to initialize the process.We never start from a white sheet, without a priori, we must always start from an intuition, an initial prejudice.What then counts is on the one hand to collect as widely as possible information to test the likelihood of his prejudice and then to accept to update and therefore potentially to call into question his prejudice if the observations are not in accordance withthis last.

Take the example of the following proposal "Immigration is not a chance for France", quite commonly widespread among the French population if we believe certain opinion surveys.No doubt that part of this judgment is based on questionable ideological a priori as the feeling of a superiority of the natives over immigrants.But this judgment is also reinforced by a series of observations in daily life, both in terms of incivility and delinquency (supported by certain statistics concerning the prison population), integration (linked toThe cultural distance between the departure society and the host society) or economic integration (linked to a level of qualification of immigrants often lower than the national average).It is therefore delicate to deny in block the proposal cited above, Bayesian inference rather coming to consolidate its likelihood.This does not prevent moreover from having completely divergent political views on what should be done on this subject, either that we consider that the difficulties of integration are inherent in massive immigrationAnd that it is therefore advisable to reduce it drastically, either that we consider that it is the organization of our society to fully integrate immigrants who are failing (in particular by concentrating the difficulties in certain districts).

It is therefore not the prejudices that are condemnable in itself, but rather certain provisions of mind which enclose individuals in their certainties: the absence of curiosity and open -mindedness to confront his prejudice with reality, uniformityor the low reliability of the information sources used (with the risk of consolidating its prejudices by remaining locked in an ideological bubble), the inability to question its prejudices (sign of a system of system where the model becomes more truethat the real), or the bad apprehension of the uncertainties (inherent in any model).

If we manage to avoid these cognitive traps, then there is no particular reason to challenge oneself of its prejudices, which represent a sum of experiences collected during its life, which therefore have an important value and that'It would be wrong to try to deconstruct at all costs.It would be, for once, completely irrational to reject in principle all our prejudices and to hold for false everything that is not certain.This approach is perhaps philosophically attractive, by registering in the footsteps of Descartes and his famous cogito ("I think so I am"), the only certainty that remains when we challenge everything else.But it is not at all suitable for attempts to understand the world around us, which we are forced to apply, a priori, that it really exists.

If it is healthy and legitimate to be wary of ideas that naturally make us happy, because they can alter our judgment, we would be wrong to hold for likely everything that appears to be counter-intuitive.Just as there is a stupidity of ignorance, there is also a stupidity of intelligence, when abstraction amounts to systematically denying common sense.

Of course, major scientific discoveries often question certain fundamental intuitions.It is far from being obvious to think a priori that the earth is round, that it revolves around the sun, that the simultaneity of two events depends on the observer (as we learn from restricted relativity) or that'Man descends from primates (as we learn from the theory of evolution).These counter-intuitive truths are today very solidly established, thanks to a repetition of experiences and an incomparable collection of knowledge.Such counter-intuitions also exist in the social sciences, but they are more fragile and perishable by nature because the experiences are more difficult to control and repeatable and that individuals and human societies can react to the theories that are planned on them,Unlike the stones and atoms that do what to do with what Newton or Einstein say about them.

It is therefore advisable, in public debate, to be careful and not to be impressed by the majority opinion, nor seduce by the temptation of the paradox at all costs.Do not reject our prejudices in principle but agree to question them.Think both by and against yourself, with common sense and requirement.