- N.F. Character of what is certain, obvious, indubitable: a mathematical certainty. Conviction, full and whole insurance: I have the certainty which it will make a success of
(Def. the Small one )
Use of the concept of Certainty has had, for antiquity, summer the object of multiple philosophical warnings by often indicating it like one . , in The republic, wonders about some illusion of the knowledge: an immediate certainty (or opinion) that one should distinguish from , in that which it can have external appearances without being it completely.
Philosophically, the concept of Certainty thus does not recut a priori concepts of truth and forgery. It is generally by Philosophy, Mathematics or byheart that this ideal perhaps reached: let us note however that this reflexion is limited to a metaphysical step, and could not yet be considered from a point of view purely (Theorem ofuncertainty of Eisengerg), mathematics (Theorem of Godel), even linguistics (, Wittgenstein).
Descartes, mathematician physicist and philosopher, aspire with the Cartesian project to a universal science deduced from the mathematical laws. Distinguishing on the one hand the spirit and on the other hand the body, it allots to this last properties deductible by employment from mathematical certainty, they same deduced from more general laws.
The Cartesian project thus approaches some , in that which it does not reject the existence of law whose veracity could not be questioned any more. In some kinds, it regards as closely dependent the concept of Certainty and the concepts mathemathic. Let us note however that the Corps/Esprit distinction does not allow, according to the Cartesian project, to conclude that the mathematical concepts are the single substrates of the Certainty: the existence of a heart, like thinking substance, is not any doubt for Descartes and constitutes well in oneself another form of certainty, as formulated by small Larousse.
, author of , will carry its certainty only in the faith: he even scientific and large mathematician of the time, reconnait in the science of the fundamental limitations which cannot enable him to acquire absolute certainty. It then defers this ideal in the faith:
- As I do not know from where I come, as I do not know either where I go; I know only that while leaving this world, I fall forever or in nothing, or the hands of God...
- God is or It is not! But on which side will we lean? Can the reason nothing determine... thus which bet to take?... Take the profit and the loss... God is or is not. Let us estimate these two cases - if you gain, you gain all; if you lose, you do not lose anything. Thus guarantee that It is, without hesitating...
Incomplétude, Uncertainty and Statistics
The physical world, however, will know several epistemological upheavals which go, at least in the scientific sphere, to substitute at the end Certitude that more relative of .
(XVIII), French mathematician and physicist, are in particular known for his design of a demon (or demon of Laplace) able to know, at a given moment, all the parameters of all the particles of the universe. From this point of view, the author adopts a position known as , that is to say a design philosophical and scientific wanting to be capable of inférer what must be, of what is. In other words, Laplace melts this concept on the concept of cause for purpose: any cause will produce the same effects invariably, which would make it possible such a demon to predict the future and to know with certainty the past.
This concept of demon will be called into question, physically, by ofHeisenberg, which stipulates that to know exactly the position and the speed of a particle at the same moment T is impossible. And this, for experimental reasons.
In , but also in formal logic, will be made known by theorem of incomplétude : it indicates that any axiomatic base, when it tends towards complexity, increases the number of proposals known as indécidables, that is to say axioms of which it is impossible to prove the truth or falseness differently than by introducing other axioms. Thus the Cartesian ideal of Certainty, from a logical point of view, is cancelled by this principle.
Critical of the Certainty
According to Carnéade
There is no criterion of the truth, because there is no true representation. The thesis is directed particularly against , which admits the existence of representations expressing their truth intrinsically. (Acad., II, XIII, 41) summarizes in four proposals this thesis of and of the Academy:
- there are false representations;
- these representations do not allow an unquestionable knowledge;
- if representations do not have between them any difference, one cannot distinguish to them degrè from certainty;
- there is no true representation distinct from a false representation.
This argumentation is so solid that it was still the starting point of of , in the first chapter of Problems of Philosophy : the variations of our representations do not enable us to affirm with certainty that an object has such color, such form and such movement. The truth does not appear with obviousness in the testimony of our directions; the representation is thus not a criterion of truth.
Moreover, the reasoning of the sorite, which, while adding to one of small quantities, forwards imperceptibly to a great quantity, shows that one could not put precise limits nowhere, even less between our representations.
But, for Carnéade, as the whole of the philosophers skeptics, does not have either the ability to make known to us the things such as they are in themselves. The reason alone, without representation, cannot indeed know the world. But, even considered in itself of the reason leads to insurmountable contradictions. Carnéade went égalment until calling in question the certainty of . Thus, according to Clitomaque (, Acad., II, XXXIV, 108):
- To drive out our hearts this frightening and savage monster that one calls the precipitation of the judgement, here is the work of Hercules that Carnéade achieved.
This criticism of certainty led to the state of incomprehension (acatalepsy), state in which one suspends his judgement and one of nothing believes. So the same difficulty which had arisen to the skeptics and for Arcésilas will arise in Carnéade: if to act, it should be believed, how to act, if nothing can be believed?
(extract of the article )
- of Ludwig Wittgenstein; 1951 (posthumous)
- of ; 1781
- The Discourse on Method of ; 1637
(HTTP://www.relst.uiuc.edu/durkheim/Texts/1884a/39.HTML) (The Durkeim pages)