What is Laplace’s Demon?

We explain this philosophical concept that tries to determine reality based on predictions.

The search for certainty and the illusion of knowing what will happen tomorrow is something that has accompanied philosophical reflections and scientific practices throughout time.

If we could be certain that tomorrow it would rain, or a war would break out, the decisions we would make today would surely be very different from those we would make without knowledge of the future. Laplace's Demon is a character that represents all of this very well.Where does he come from?

Laplace's Demon and the problem of prediction

The illusion of predicting and controlling what surrounds us is a theme that can be found in much of scientific development. For example, classical mechanics was based on the idea that everything that exists in the universe and nature can be known through logical mathematical reasoning, as well as through a geometric system to measure and predict what will happen.

In other words, Classical mechanics starts from the consideration that the universe and nature are governed by a series of initial laws that can be unveiled by human beings for their modification.

For example, modern astronomy in the West, inaugurated by Newton, has this position as its antecedent.

Who was Pierre Laplace?

Pierre Laplace was a French astronomer, physicist and mathematician who lived from 1749 to 1826.. He is credited with the development of celestial mechanics, worked hand in hand with Isaac Newton and Galileo in the prediction of eclipses and the discovery of new planets. He also participated in the study of some gas molecules and atomic particles.

What Laplace suggested from his knowledge is that, through science, we can foresee and guess the activity of all the behavioral systems that exist. And if not, unpredictability would only be an error of knowledge that, as such, can be corrected.

In Laplace's deterministic conception, everything can be predicted.and if it is not so, it is because the knowledge produced by the human being has erred or is not sufficient.

What this means is that everything that exists in the universe is structured in a prior and independent way to the activity of human beings, so that our own actions and everything we are would be predetermined by the laws of the universe.

The deterministic demon (Laplace's)

Laplace's Demon is an imaginary character who has the power to know the initial properties of all the particles of nature and of the universe, with such precision that he can apply the natural laws to guess what will happen instantly or in a long time; from a precise movement to a work of art (Calabrese, 1999).

In other words, Laplace's Demon is a deterministic and all-powerful demon, a being that is external to the universe.a being that is external to the universe and that has predicted and decided every single thing that will happen in nature, including, of course, the activity of human beings.

The logic of prediction was not only transcendental in astronomy, the sciences of physics, mathematics and the natural sciences, but has extended to the study of human behavior as well as human intervention.

For example, it has been present in the development of modern medicine, and we could even see how it impacted the traditional way of doing human sciences, as well as economic and financial activity. However, since the development of new scientific paradigms, Laplace's Demon has encountered some limits.

From determinism to indeterminism: the end of certainty

The logic of prediction was particularly successful as long as the universe was understood in terms of linear systems, based on a stable cause-effect relationship. But when chaos theory and quantum mechanics came along to challenge the linearity of all systems, the scientific field also questioned the insistence on applying the logic of prediction to everything we know.

Broadly speaking and among other things, there was a paradigm shift from considering that in non-linear systems (which are complex systems, with chaotic and non-cyclic behaviors, as in human beings), the initial state is not equal to the final state, nor does it determine it, and therefore, they are systems that cannot be predicted.

In the field of science, the universe and nature in general cease to be conceived as a set of laws of general coverage, pre-established by an external being.. Thus, from the beginning of the twentieth century, there is an important turn where it is considered that, although it is possible to calculate probabilities, there can always be failures of prediction. From this, some authors consider that an era marked by the end of certainty is inaugurated, especially in the human and social sciences.

Bibliographical references:

• Trainini, J. (2003). Towards the need for a new medical paradigm. Revista Argentina de Cardiología, 71(6): 439-445.
• Calabrese, J. L. (1999). Extending the frontiers of reductionism. Deduction and nonlinear systems. Psychoanalysis APdeBA, XXI (3): 431-453.
• Wallerstein, IM (1999). The social sciences and humanities on the threshold of the twenty-first century. The end of certainty in the social sciences. UNAM: Mexico.