The Definition of Determinism Needs Updating
Version date: June 27, 2008
This text summarizes in 5 pages the 440 pages of the book
in order to let anyone appreciate if it is interesting to read.
What is determinism?
With the postulate of causality on which it is based, determinism is one of the foundations of rational thinking. Determinism governs the evolution of a situation from its initial state (the cause) to its final state (the consequence).It helps understand observed situations, predict their evolution, and explain how the past we know led to the present we observe.
The traditional definition of philosophical determinism was given by the French scientist Laplace in 1814. The Laplacian determinism postulates the existence of a unique causal chain beginning infinitely far in the past and continuing infinitely far in the future. Here is a translation of how Laplace stated his postulate in his text "Essai philosophique sur les probabilités" (A Philosophical Essay on Probabilities").
"We should consider the present state of the Universe as the effect of its previous state and the cause of the state that will follow. An intelligence which, at a given time, would know all of the forces that govern nature and the respective states of all its beings – assuming it is vast enough to analyze that data – would grasp in the same formula the movements of the largest bodies of the Universe and those of its lightest atom; nothing would be uncertain for it, the future and the past alike would stand before its eyes."
(That intelligence is often termed "Laplace's demon").
The postulate of causality is a necessary and sufficient condition:
§ Necessary condition: in the absence of the cause, the consequence does not occur;
§ Sufficient condition: if the cause exists initially, then the consequence occurs afterwards (it is certain).
Traditional scientific determinism is defined by this necessary and sufficient condition and a stability rule: the same cause always produces the same effect: the effect of a cause is reproducible. The physical laws whose action produces the consequence of a cause are stable; they are the same everywhere and at all times.
Therefore, traditional determinism, philosophical or scientific, excludes:
§ Chance: the result of throwing a dice – an integer number from 1 to 6 – is considered non-deterministic;
§ Interventions which are supernatural (due to a cause or a law of evolution external to our Universe) or unpredictable (they are not the result of any cause or physical law, known or to be discovered).
The traditional definition of determinism is contradicted by the behavior of nature
Determinism, which is intended for helping us predict with certainty what will happen, is contradicted by known physical phenomena. Here are three examples among the dozens described in the book:
§ Radioactive decay (nuclear fission)
The atoms of a sample of uranium 238 decay (decompose) spontaneously, without any cause other than passing time; an atom of uranium then breaks into an atom of helium and an atom of thorium. The number of atoms of uranium 238 that decay per unit of time follows a known law: 50% of the atoms of a sample of arbitrary size will decay in a fixed amount of time T termed "the half-life of uranium 238"; then half of the rest (one quarter) will decay during the next period of time T; then half of the rest (one eighth) will decay during the next period of time T, etc.
Radioactive decay is attributed to the instability of the excitation energy of the neutrons and protons of a radioactive atom's nucleus. This energy varies spontaneously – a phenomenon deemed impossible in traditional deterministic physics. Due to a tunnel effect, this excitation energy may sometimes exceed the potential energy that holds the nucleus together, known as the element's fission barrier, causing the atom to decay. The tunnel effect and its spontaneous nature can only be explained using the mathematical tools of quantum mechanics, which contradict traditional determinism by introducing spontaneous variations of energy levels and probabilities in the occurrence of an event.
Traditional determinism is also contradicted by the fact that it is impossible to know which atoms will decay during a given period of time, and at what point in time a given atom will decay.
Radioactive decay has a statistical nature, with a law that is valid for a population of atoms but cannot predict the evolution of a given atom, which contradicts determinism as a principle for predicting the future. Also, when a sample contains decayed atoms, it is impossible to know for any one of them at what time it decayed, and that contradicts determinism as a principle for deducing past events from the knowledge of the current situation and the law of evolution that applied.
§ Motion of an atomic particle
An atomic particle such as an electron has no well-defined trajectory after it leaves a given point of space, and its velocity cannot be defined with an arbitrary precision. Its trajectory may only be defined as occupying a volume of space, at every point of which it will have, at a given time, a probability of being there and a probability of having a given velocity. The probabilistic nature of an electron's trajectory contradicts traditional determinism: obeying the same physical laws of forces as macroscopic objects, whose movement is predictable with an arbitrary precision, an electron's movement is only predictable in probabilistic form. In addition, it is impossible to measure the size of an atom's nucleus (its diameter, assuming that it is spherical and does not go out of shape too much).
In the case of atomic particles, the chain of causal possibilities is described by a tree diagram, in which each node associated with a situation may be followed by several branches (not one, as traditional determinism predicts), each of which is associated with a different evolution and ends with a different consequence node. Actually, many phenomena of macroscopic physics may also produce multiple consequences of a given cause, for example in the form of accumulation points of the phase space, a fact that explains the sudden appearance of new species in Darwinian evolution.
Another strong contradiction of traditional determinism is that in some situations the action of a law of evolution on a given cause produces several consequences that are superimposed (they exist simultaneously!)
The replacement of the single causal chain of determinism by a tree structure, and the possibility for a single cause to produce several superimposed effects, contradict traditional determinism.
§ Quantum fluctuations
Traditional determinism is also disproved by quantum energy fluctuations that occur spontaneously in the empty space between atoms or between galaxies. Those fluctuations cause pairs of particles to appear, "borrowing" their energy from surrounding space, then disappearing and "returning" the energy. From the point of view of traditional determinism, these fluctuations are totally spontaneous and unpredictable; this natural phenomenon seems to have no cause. It is impossible to predict where a particle pair will appear, when it will appear, and how much energy will be borrowed.
Even when matter is infinitely concentrated and dense, as is the case in a black hole, there are energy fluctuations that continuously cause particles to appear and disappear; some of these particles may even appear outside the black hole, causing it to "evaporate"! And in the extremely dense Universe that existed shortly after the Big Bang - a Universe so homogenous that relative homogeneity differences were less than 1 part in 100 000 - colossal energy fluctuations caused areas of high energy density to appear, and those areas later became galaxies! Such phenomena definitely contradict traditional determinism.
Substituting ignorance for randomness
Even though Laplacian determinism excluded chance, traditional philosophy postulated that nature is deterministic… except when it isn't because some phenomena exhibit randomness! Man's unconscious needs order for its comfort, so postulating determinism was a way of declaring that nature was ordered, which was reassuring. When some phenomena appeared inexplicable, unstable or impossible to describe without probabilities (like throwing dice), they were deemed exceptional and were attributed to randomness or to God's will. Some types of randomness were even considered irreducible, such that we will never be able to explain them, no matter what scientific progress we make. That is why Laplace (a supporter of Enlightenment who believed in the ultimate triumph of Reason) excluded randomness from his definition of determinism, thereby implying that sufficient knowledge and scientific progress would make the outcome of every phenomenon predictable in the future. In the early 20th century, Einstein himself considered probabilistic physics a temporary substitute for an in-depth knowledge of the laws of nature at atomic scale; he once said "God does not play dice with the Universe".
Since we know today that some physical phenomena are intrinsically random and cannot be described without mathematical probabilities, we have only two alternatives:
§ Either we decide that the phenomena of the Universe are sometimes unpredictable and our knowledge of their outcome is forever bound to be limited, an attitude that renounces scientific progress in some areas.
§ Or we decide to include the mathematics of randomness in our representation of nature, just as we include other equations in deterministic models such as Newton's laws of motion that describe non-random physical phenomena.
In this book, I show how the second alternative constitutes a natural extension of traditional determinism indispensable to make it consistent with modern physics, an extension that unifies our methods for representing the world.
Some deterministic phenomena produce an unpredictable outcome
This book contains examples of well-known phenomena, whose initial state and law of evolution are known without uncertainty, but for which we have a proof that the outcome is impossible to predict because there cannot exist an algorithm to calculate it. Such phenomena are further examples of the inadequacy of traditional determinism.
This book also contains examples of phenomena that have an outcome predictable in theory but not in practice, because they comprise too many component phenomena that are individually deterministic and predictable.
Some certainties are unprovable
There are descriptions of situations or of laws of evolution for which it has been proven that no demonstration may exist; some are true, others are false. They are termed undecidable. Such descriptions are exceptions to the causal principle, because if they had a cause that is certain their existence would be certain, and their truth would also be certain. Their existence excludes predicting the result of human thoughts, therefore disproving determinism in their case; but contrary to some philosophers' opinion, it does not prove that nature is not deterministic (the book provides details).
A proposal for describing the laws of nature: update our definition of determinism
This book shows that an enriched definition of determinism enables us to predict the outcome of every phenomenon for which our scientific knowledge is sufficient, including phenomena that have a probabilistic model. This enriched (extended) definition is derived from two certainties about the laws of the Universe: 1) it is homogenous and isotropic; and 2) the laws of physics are stable through time. The causal principle may easily be derived from those facts.
All our surprises when we consider some situations or evolutions are due to defective mental representations of reality. These representations are based on concepts and logic imagined in the days of Newton or shortly thereafter, and are derived from our senses' experience. If we accept to supplement such traditional concepts as time, space and mass, with more elaborate concepts such as those provided by the mathematical postulates and tools of quantum mechanics, the difficulties and counterexamples due to randomness and probabilistic behaviors disappear:
§ Physics becomes deterministic again and devoid of surprises within the framework of extended determinism.
§ When they think beyond science, philosophers may use a new definition of determinism, which is up-to-date and conforms to reality.
A critique of determinism
In this book, I analyze reasons to criticize determinism and the causal principle, and to redefine their limits. I first propose rational and philosophical reasons that disprove the traditional definition of determinism. I then describe in detail the modern approach of scientific discovery based on Karl Popper's falsifiability requirements, and compare it with empiricism in order to find potential flaws in the method for establishing the scientific truths on which determinism is based.
Are the rules that govern living beings deterministic?
Man is also part of nature, and this book describes some of the rules that govern his neurons, his mind and his behavior, in order to find their relationships with extended determinism. The description features recent scientific advances in the fields of molecular biology and neurology which prove that all phenomena of living beings are based on mechanisms governed by extended determinism, even though some have an unpredictable outcome. This is the case, for example, for the cellular mechanisms based on the interpretation of the genomic software, and for complex phenomena such as thinking.
The text also shows that most psychic phenomena have non-predictable outcomes, either because they are undecidable, or because they depend on so many variables that the deterministic rules of many phenomena produce results that are unpredictable or plagued by a lot of uncertainty.
The rules that govern the behavior of a population of economic agents are deterministic
The book uses the example of economic globalization to show that it too is governed by extended determinism. Globalization is inevitable, but it is also a framework for implementing solutions to the serious environmental and societal problems it brings about.
Determinism and man's free will
With the exception of a few philosophers such as Nietzsche, who advise men to accept reality even when it implies that man's decisions are not free and nature is meaningless - which leaves but little hope - most philosophers assert that man is free to think and act as he chooses. They often uphold this opinion to justify their intuitive belief in the reality of man's free will, and their moral requirement to declare each man responsible for his acts. I explain some reasons why they are mistaken such as confusing number of alternatives and process of choosing among them. The immense number of variables of each situation in a man's life makes the number of courses of action he may choose from innumerable; and even though every choice is constrained by extended determinism, the number of possibilities and each man's ignorance give him the impression that he has free will, when indeed he does not.
This is what I wanted to do. I needed about 440 pages to express it, sorry about the length. Writing the initial text in French required about one thousand hours, then translating it into English doubled that duration because English is not my mother tongue.
In addition to the book above, two short complements of this text are available:
§ A concise definition of extended determinism deduced form the properties of the Universe (8 pages)