Principle of sufficient reason

The German philosopher Gottfried Leibniz was one of the main promoters of the principle of sufficient reason.

The principle of sufficient reason (in Latin: principe de raison suffisante / principium reddendae rationis) is a philosophical principle according to which everything that happens has a reason enough to make it like this and not otherwise, or in other words, everything has a sufficient explanation. The German philosopher Gottfried Leibniz was one of the main promoters of the principle. In Monadology , §32: he considers that this principle is one of those that found any reasoning. "We consider that no fact can be true without there being a sufficient reason for it to be so and not otherwise." This principle has antecedents throughout the history of philosophy.

Formulation

The principle of sufficient reason admits various formulations, all of which can be reduced to one of the following forms:

• For any entity XYeah. X exists, then there is a sufficient explanation for why "X It exists."
• For each event EYeah. E then there is a sufficient explanation for which "E It happens."
• For each proposal PYeah. P is true, then there is a sufficient explanation for why "P That's true."

Here «sufficient explanation» can be understood as a set of reasons or causes, although many 17th and 18th century philosophers did not distinguish between these two types of « enough explanations. The result of the principle, however, is very different depending on whether a "sufficient explanation" is interpreted in one way or another.

At present it remains an open question whether the principle of sufficient reason can be considered an axiom in a logical construction such as in a mathematical theory or in a physical theory, because axioms are propositions that are accepted without the need to have a justification within the system itself.^{[citation needed]} Axioms are the basic propositions of undefined primitive notions.

Strong vs. weak

He differentiates between a strong and a weak version of the principle of sufficient reason. Alexander Pruss and Richard M. Gale differentiate them thus:

• Strong: for each proposal, p Yeah. p is true, then there is a proposition, qwhich explains p.
• Weak: for all contingent truths p It is possible that p Have an explanation.

A modal version of the principle of strong sufficient reason takes it to be necessary in all possible worlds, while a weak modal version presents it as contingently true. Pruss also presented a "weak principle of sufficient reason" 3. 4; where "possibly weak principle of sufficient reason is true" for those who think that some processes are in principle inexplicable. Graham Oppy criticized this distinction, arguing that the weak principle implies the strong principle.

Story of the beginning

Background

Idealized portrait of Leucipo.

The modern formulation of the principle is generally attributed to the early Enlightenment philosopher Gottfried Leibniz, but he was not an initiator. The principle has antecedents throughout the history of philosophy. Leibniz says:

Didn't everyone use this principle a thousand times?

Various philosophers who preceded him include: Anaximander, Parmenides, Archimedes, Plato, Aristotle, Epicurus, Cicero, Avicenna, Thomas Aquinas, and Spinoza.

The atomistic pre-Socratic philosopher Leucippus of Miletus formulated that:

"Nothing comes from chance, but from reason and necessity."

Stobeo, I, 4, 7c
Diels-Kranz, Die Fragmente der Vorsokratiker, 67 B2

It has been pointed out that it is in Anselm of Canterbury's phrase "quia Deus nihil sine ratione facit" and the formulation of the ontological argument for the existence of God. A clearer connection is with the cosmological argument for the existence of God. The principle can be seen in both Thomas Aquinas and William of Ockham. Some philosophers have associated the principle of sufficient reason with "ex nihilo nihil fit". William Hamilton identified the laws of inference modus ponens with the "law of reason sufficient, or of reason and consequent" and modus tollens with its contrapositive expression. Christian Wolff expressed the principle thus: Nihil est sine ratione cur potius sit, quam non sit.

Gottfried Leibniz

Leibniz's formulations

Leibniz identified two types of truth, necessary and contingent truths. And he affirmed that all truths are based on two principles: (1) non-contradiction and (2) sufficient reason. In the Monadology, he says:

Our reasonings are based on two great principles: that of contradiction... and that of reason enough, by virtue of which we believe that no fact could be found to be true or existing, no true statement, without there being sufficient reason for that to be so and not otherwise, although these reasons may not be known to us more often.

Monadology, §31-32.

Necessary truths can be derived from the law of identity (and from the principle of non-contradiction): "Necessary truths are those that can be proved by an analysis of terms, so that in the end they become identities, just as in algebra an equation expressing an identity ultimately results from the substitution of values [by variables]. That is, necessary truths depend on the principle of contradiction". The sufficient reason for a necessary truth is that its negation is a contradiction.

Leibniz admitted contingent truths, that is, facts in the world that are not necessarily true, but are nevertheless true. Even these contingent truths, according to Leibniz, can only exist on the basis of sufficient reasons. Leibniz states that not everything possible exists. "Once this is admitted it follows that some possibles come into existence rather than others not out of absolute necessity but for some other reason (such as goodness, order, perfection)." Leibniz describes the principle as principium redendae rationis (principle for which reason must be given). In Theoría motus abstracti (secs. 23-24) he says: «Nothing happens without reason», from which he establishes the conditions that unstable changes must be avoided; between opposites choose the middle ground; and to be able to add to any term what we please as long as it does not cause damage to any other term; for "this most noble principle of sufficient reason" it is "the apex of rationality in movement".

[J]something else happens without a cause or at least a determining reason, that is, something that can serve to give a priori reason why something exists and why it exists this way rather than otherwise.

Théodicée, I, 44.

Leibniz's arguments in favor of the principle

In Ferrater Mora's Dictionary of Philosophy, three arguments that Leibniz held in favor of the principle are presented:

1. There is something rather than nothing because there is a sufficient reason: the superiority of being over non-being.
2. There is no void in Nature, because then it would have to explain why certain parts are occupied and others are not, and the reason for this cannot be found in the void itself.
3. Matter cannot be reduced to extension because there would be no reason to explain why a part of the matter is in place x rather than the place and.

Consequences of Leibniz's principle

According to the principle of sufficient reason, all events that at first glance seem random or contingent actually have a sufficient explanation, their apparent incomprehensibility is that we do not have complete knowledge of them. For the rationalist tradition, the principle of sufficient reason is the foundation of all truth, since it allows us to establish what is the condition (the reason) of the truth of a proposition. Everything that happens has in itself a sufficient reason. A complete analysis would make this reason clear. Ultimately, for God, everything is true of reason. Cartesian rationalism considers that the analytical decomposition of any fact into simpler elements allows us to know the logical order that complex things constitute, as well as the causal relationships between them. Consequently, the traditional Aristotelian logic of the intuition of essences by the understanding as a faculty of the soul, is now interpreted by the rationalist logic of Port Royal as a logic of attribution to a notion that is known as an idea in consciousness, not as an intuition of the reality of the essence as had been been until now. For this reason, the predicate is an attribute or mode of the subject as a substance, knowable through analysis, according to a thorough knowledge of the elements that constitute it as a substance and the causes (relationships with other substances) that made it possible and existing in the world of experience. In other words, everything is necessary because ultimately all truths would be for us truths of reason if we could submit reality to a complete analysis. Thus rationalism is based on the assumption that truths in fact are truths of reason. In Descartes' rationalism, if there is a "God" or being with an infinite capacity for analysis, he could know that all the truths in the world are in fact truths of reason.

René Descartes.

The Cartesian mechanism would seem to be based on this principle, provided that a radical dualism is maintained: the thinking substance, res cogitans, and the extensive substance, res extensa. But Leibniz did not admit such dualism in his metaphysical conception. He considered it an unjustifiable mechanism due to its condition of extensive matter and justified the substance with his concept of monad. Thus Leibniz considers that the existing order in the world is a "harmony pre-established by God" and the apparent freedom of man is an immanent action of the monads.

To justify the fact of freedom, the phrase used by Leibniz himself to explain his principle and the truths of reason has become famous: «Caesar crossed the Rubicon». Considering that the fact of passing the Rubicon apparently does not come from the analysis of the notion of Caesar. Since Caesar being a free being, he could not have crossed the Rubicon, without ceasing to be Caesar. However, since, in fact, he crossed the Rubicon there must be a sufficient reason for him to do so, and that reason can only lie in Caesar's own essence. The Caesar who had not crossed the Rubicon would no longer be the same Caesar, he would be another Caesar. For Caesar is constituted as such in his predicates. Only a complete analysis of all that constitutes the notion of Caesar would explain the necessary truth, and therefore truth of reason of the fact: "Caesar passed the Rubicon"

These analyzes cover only a few mundane elements that give us reason and explain a factual, contingent truth that could not have been; but for God, everything happens according to a sufficient reason contained in the notion of each monad. The set and purpose of the sufficient reason for the action of all the monads, as a whole as a real world, compared to all possible worlds cannot be other than: "This is the best world of all possible ones." Leibniz used this principle as an answer to the problem of evil, a theodicy. He writes in his Letter to des Bosses in 1711: “if there were not the best possible series, God would not have created anything, since he cannot act without reason or prefer the less perfect to the more perfect”. Thus, the Perfection and Goodness of God or the deception of a powerful demon that pretends to be God is justified. Only if God decides to exist by his will could he know that God is himself.

Another just less general principle in its application than the principle of contradiction applies to the nature of freedom. It is the principle that nothing happens without the possibility that an omniscient mind can give some reason why it happens rather than does not happen. Moreover, it seems to me that this principle has contingents the same use as for the necessary things.

Samuel Clarke noted a difficulty in applying even to human behavior the principle of sufficient reason: "someone who has a good reason to do A or B, but has no reason to do one of these instead of the other, it will surely choose one arbitrarily instead of doing nothing". Since sufficient reasons for contingent truths are largely unknown to humans, Leibniz appealed to infinitely many sufficient reasons, to which only God has access:

In the contingent truths, even if the preacher is in the subject, it can never be demonstrated, nor can a proposition ever be reduced to equality or an identity, but the resolution proceeds to the infinite, seeing only God, not the end of the resolution, of course, that it does not exist, but the connection of the terms or the containment of the preached in the subject, for he sees what is in the series.

Without this qualification, the principle can be seen as a description of a certain notion of a closed system, in which there is no 'outside' that provides causes for unexplained events. It is also in tension with Buridan's donkey paradox (the absurd case of a donkey not knowing how to choose between two stacks of hay and consequently ending up starving to death), for although the facts assumed in the paradox would present a counterexample to the claim that all contingent truths are determined by sufficient reasons, the paradox's key premise must be rejected when considering Leibniz's typical infinitary worldview.

Consequently, the case of Buridan's ass between two meadows, equally driven towards both, is a fiction that cannot occur in the universe... For the universe it cannot be cut by half vertically in all its length, so everything is equal and similar on both sides... Neither the parts of the universe nor the animal's viscera are equal nor evenly placed on both sides of this vertical plane. Therefore, there will always be many things in the ass and out of the ass, although they are not apparent to us, that will determine to go on one side and not on the other. And although man is free and the ass is not, however, for the same reason it must be true that in man it is equally impossible the case of a perfect balance between two courses. (Teodicea, p. 150)

Leibniz also used the principle of sufficient reason to refute the idea of absolute space:

I say then, that if space is an absolute being, there would be something for which it would be impossible for there to be sufficient reason. Which goes against my axiom. And I show it like that. Space is something absolutely uniform; and without the things placed on it, a point in space does not differ absolutely in any aspect of another point of space. Now, from here it follows (assuming that space is something in itself, in addition to the order of the bodies among itself), that it is impossible for there to be a reason why God, keeping the same situation of the bodies among himself, has placed them in space in a particular way, and not of another; why everything was not placed completely contrary, for example, by changing the East by the West.

Interpretations of the principle

Christian Wolff.

Christian Wolff derived in Ontology the principle of sufficient reason from the principle of non-contradiction and links it to the notion of cause.

Per rationem sufficientem intelligimus id, unde intelligitur, cur aliquid sit. (We understand for reason enough that which is why something exists.)

This ontological interpretation has been maintained as a derivation of the principle of non-contradiction. And it has been the interpretation that has prevailed for a long time in the rationalists and neo-scholastics of the 19th century. Immanuel Kant sees the principle as "so plausible that even common sense agrees", saying in the Critique of Pure Reason that "it is the ground of possible experience., that is, the objective knowledge of appearances with respect to their relationship in the successive time series".

Arthur Schopenhauer.

Arthur Schopenhauer in his work On the fourfold root of the principle of sufficient reason (1813) points out four forms of said principle:

• The reason that everything that happens in physical or material objects can be explained.
• The reason that there is a reason why a particular proposition is true.
• The reason that any property relative to geometric numbers or figures is explained in terms of other properties.
• The reason someone does what they do.

Schopenhauer wrote about the importance of the principle of sufficient reason in scholarship:

The importance of the principle of sufficient reason is great, because it can be considered as the foundation of all sciences. Science is nothing but a system of knowledge, that is, a whole of linked knowledge, in opposition to a mere addition of them. And who but the principle of sufficient reason links the members of a system? What distinguishes precisely a science from a mere aggregate is that its knowledge is born from one another as of its own reason... In addition, all sciences contain notions of cause, for which the effects can be determined, and also other knowledge about the needs of the consequences from the principles, as will be seen in our further consideration... Now, as the assumption always made by us a priori that everything has a reason is that which allows us to ask everywhere "why", the "why" can be called the mother of all sciences.

Such principles are applied to four needs: physical, logical, mathematical and moral needs.

Bertrand Russell.

Alexander Pfänder considers the genuinely logical meaning of the principle, according to which it rests on the "internal connection that the truth of a judgment has, on the one hand, with the "judgment"". a priori does not limit the possibility of the action of each monad in its interior, because in reality the succession is a harmony pre-established by God who has chosen the "best possible world"; "on the other hand with sufficient reason", and is therefore a principle applicable only to the judgment and to the condition of truth, which is equivalent, basically, to the possibility of being true. Bertrand Russell considers that the principle of Sufficient reason encompasses two principles:

• One of a general nature that applies to all possible worlds.
• Another special that applies only to the present world.

Both principles refer to existent, possible or actual, but while the first is a form of the law of (final) causality, the second consists of the affirmation that all actual causal production is determined by the desire for the good. The first has a metaphysically necessary character (principle of possible contingents) while the second is contingent (principle of actual contingents).

Martin Heidegger.

Heidegger considers this principle as a central question of metaphysics since it concerns the question of foundation. He considers that it has two aspects:

• negative: nihil est sine ratione (nothing exists without a reason)
• affirmative: omne ens habet rationem (all right)

For Heidegger, the negative form is more fundamental, since it does not concern the things of which something is affirmed, but the foundation of things, of which foundation nothing is affirmed. For Heidegger, the principle is misinterpreted by confusing «reason» with «foundation». Therefore the principle declares there is nothing without reason, therefore he declares that the principle is not without reason, but he does not give the reason for the foundation. The reason for the beginning is not found in the beginning. For Heidegger, the meaning of this little principle of reason (der kleine Satz von Grund) is the original meaning of the "logos", as what "makes itself seen", what opens from the to be to become "present". In this way this small principle becomes the great principle (grosse Grundsatz), when it speaks as "word of Being" (als Wort vom Sein), calling this Being, "Reason".

Taking all of the above into account, the various ways of understanding the principle of sufficient reason acquire the following ways of understanding:

• the ontological
• logic
• psychological or gnoseological
• metaphysics

José Ferrater Mora concludes that all these modes are related: it can be considered ontological, but at the same time it is logical or logically formulatable; but at the same time it is a principle that is imposed on all thinking and, as such, all thinking as thought has its origin in the principle of reason.

In literature

Voltaire made a harsh criticism of the principle of sufficient reason as Leibniz had formulated in his novel ♪.

The principle of sufficient reason occupies a central place in Voltaire's novel Candide, published in 1759. There, this idea is criticized with a satirical tone. At the beginning of the novel, his protagonist, Candide, is an ardent adherent of the principle of sufficient reason that he had been taught by his mentor, Pangloss. Throughout the novel, unfortunate events will make Cándido increasingly critical of this principle. On the contrary, Pangloss will remain convinced of it.

Criticism

The Stanford Encyclopedia of Philosophy states that: "At first glance, the Principle seems to have strong intuitive appeal (we always ask for explanations), but many consider it too bold and costly because of the radical implications it seems to produce. " To reject the principle of sufficient reason is extremely difficult in the everyday context, almost insane. much of the best efforts of the best philosophers have been devoted to a direct frontal attack" at first. Therefore, it seems necessary to explain why philosophers bother to discuss it. Two reasons why this principle is often discussed are:

• Criticism of the consequences of the principle:

If we take this principle really seriously, it can easily lead to consequences that contradict our common sense, such as "the Identity of Indiscernibles, necessitism, the relativity of space and time, the existence of a self-necessary Being (that is, God) and the Principle of Plenitude". Taking hard determinism as an example, Peter van Inwagen and Jonathan Bennett interpret the principle of sufficient reason to imply that there are no contingent truths. It can be argued as follows way: "There is a good reason why the current state of the universe is like this" it results in the fact that the universe was completely determined in all its details from beginning to end for all time. Objections appeal to free will and the indeterminacy of quantum mechanics as incompatible with the principle.

• Validity of the principle itself:

A critique of the principle is preceded by Agrippa's Trilemma. According to which the justification of a fact falls to accept an infinite regression of explanations, a circular explanation or the existence of brute facts. Each horn questions the legitimacy of the principle.

John Leslie Mackie in The Miracle of Theism posed: "How do we know that everything must have a sufficient reason?" and "How can there be a necessary being, containing its own sufficient reason?". If the second question cannot be answered then "it will follow that things as a whole cannot have reason enough". David Hume considered that it is plausible a priori that not everything that exists has an explanation because something without sufficient cause is conceivable (smoke without fire or fire without wood). According to Leonhard Euler, many of the proofs of the Principle are petitio principii, while "others carelessly derive the impossibility of things from our ignorance of the causes of these things". This is appreciated when this principle is considered in cases where it is not sure if there really is a reason. A prominent example of these cases is the question: "Why is there something and not nothing?". This question is often rejected as a pseudo-question. However, if we see this valid question, it is very difficult to find a reason that can be easily answered there. Hence the idea that "there is no reason for this" and "there is an event that has no reason" is born. It is said that this is "thing without reason" or a brute fact. For example, Bertand Russell explained that it is fallacious to argue that the universe is contingent because all beings in it are contingent (see Fallacy of composition). Russell held that the universe is a brute fact, "it is there.", and that's it". On the other hand, Richard Swinburne held God as the ultimate 'supreme brute fact'.

Robert Nozick questions the assumption that a fundamental law or principle can explain itself by self-subsumption, by being an instance of itself. In such a case, the question arises "whether for a fact to be brute it must not be explained by anything, or if it must be explained by nothing but itself". John Post argues that the principle can be refuted from the very concepts of explanation of the principle by means of what he calls "heredity theorem".

Given a final explainer, then, it is not logical or conceptually possible that there is an explanation of its existence; not even a theistic explanation could be his only possible explanation, there was no possible explanation. Nor could there be a longing rationale to have an explanation of it, since a longing is rational only if it is consistent with rationally acceptable principles. All this applies also to the universe if, as some have argued for a long time, it is a final explanation.

Quentin Meillassoux argues in his work After Finitude in favor of what he calls 'hyper-chaos', a model of reality based explicitly on the rejection of the principle of sufficient reason.

The "principle of indifference" or "principle of insufficient reason" indicates that there may not be sufficient reason "to lean in favor of one option rather than another or others". The principle can be linked here referred to with the paradox, Buridan's Ass.

Even so, this principle is widely accepted and advocated by philosophers such as Quentin Smith. Robert C. Koons and Alexander R. Pruss criticized the rejection of the principle of sufficient reason as falling into extreme empirical skepticism.