The Relationship Between Knowledge and Certainty

Academic Paper, 2018

14 Pages, Grade: 2,3



1 Moore’s Arguments Against Idealism and Skepticism

2 Wittgenstein’s Criticism

3 Knowledge and Certainty
3.1 Knowledge versus Certainty
3.2 Objective and Subjective Certainty
3.3 The Process of Learning

4 Conclusion


The relationship between knowledge and certainty varies according to conception. I ar­gue that knowledge and certainty are usually equivalent, but there are cases in which cer­tainty is possible without knowledge and knowledge is possible without certainty

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Let A = Knowledge and в = Certainty As the Venn diagram above demonstrates, there is a region (i) in which they are the same; some knowledge is certain (А л в or A ก В). The classical platonic definition is located here; we know when we believe something that can be justified, and that is true. The concepts are related closely and are nearly interchange­able; “I know x” can be identical to “I am certain of X.” There are other two regions; certainty that is not knowledge (ii):

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and knowledge that is not certain (iii):

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I Moore’s Arguments Against Idealism and Skepticism

The connection between knowledge and certainty does not change much when consider­ing René Descartes’ philosophy because methodological skepticism consists of doubting beliefs that are uncertain. That there exist external objects is uncertain because a malicious demon could be deceiving US by creating the illusion of an external world.

Although Descartes suggests that we can doubt all of our beliefs, his concep­tion of science consists of secure insight: “Omnis scientia est cognitio certa et evidens” (Descartes 1907, p. 4). This means that all science is certain and evident knowledge, or a high degree of certainty.1

Three centuries later, G. E. Moore had another reasoning when writing “A De­fense of Common Sense” and “Proof of an External World.” He suggests that doubting that the world exists is unnecessary; we must trust that the universe exists. He is against George Berkeley’s suggestion that matter does not exist; everything is just ideas of the mind of God, and to be is to perceive.2 This is similar to propositions from Gottfried Wilhelm Leibniz, who was an idealist because he claimed that all possible worlds lie in God, and we are substances observing the best alternative (Leibniz 2014, §43-46).

Moore suggests that it is irrational to believe such premises. He held intuitions that a person has in everyday life, the common sense philosophy. We cannot be certain yet we claim to know many things. Moore also purports that the external world is real and he tried to prove it (Moore 1993a, p. 166).

His argument goes as follows:

Pi: Here is one hand.

P2: Here is another.

Cl: There are at least two external objects in the world.

C2: Therefore, an external world exists.

He argues that he had the experience of observing his hands and reiterates that at least his hands offer the sum of two objects, which at a specified time existed (Ibid., p. 163).

Moore argues that he knows there existed one hand at that moment. Although Moore does accept that we cannot prove the premises of the argument, what other philo­sophers such as Kant pursued (Moore 1993a, p. 169), he suggests that we can know, that we know many things, and to say that we only believe them is absurd. To say that we believe that the world exists is not as cogent as saying that we know it. But does it make sense to say that we know it?

Contrary to Moore, many philosophers suggest that the proof does not work. Among such criticisms are Wittgenstein’s, whose last work was inspired by Moore, espe­cially the truisms that Moore claimed he knows with certainty to correspond to the truth, including propositions such as knowing that we have body parts, knowing what time it is, or knowing family and friends. Truisms that Moore mentions include:

Among the things which have, in this sense, formed part of its environment (i.e., have been either in contact with it, or at some distance from it, however great) there have, at every moment since its birth, been large numbers of other living human bodies, each of which has, like it, (a) at some time been born, (b) continued to exist from some time after birth, (c) been, at every moment of its life after birth, either in contact with or not far from the surface of the earth; and many of these bodies have already died and ceased to exist. But the earth had existed also for many years before my body was born; and for many of these years, also, large numbers of hu­man bodies had, at every moment, been alive upon it; and many of these bodies had died and ceased to exist before it was born. (Moore 1993b, 10JÍ)

Moore argues that there is a here and now that we should not deny—all matter, all bodies that we encounter, we interact with in the world a) since we were born, b) experiencing life, and c) are on earth, and not just me; many bodies have existed during the history of life on earth. According to Moore, we know that we are here until we cease to exist, but new people come into the world. Moorean truisms have to do with the truths that we all perceive as beings who come into this world, grow, live, and die. Humans have organs such as brains, hearts, and lungs. There are other animals, trees, and flowers, such as roses, daisies, and lilies. Today the weather was sunny, and thus everyone in Berlin felt the warmth. We experience the certainty of truisms, that is inter-subjective, and we all share them because we are interconnected. We interact, and thus Moore’s point is crucial because we should not deny our experiences in the world.

Wittgenstein’s Criticism

Moorean truisms address the point in the Venn diagram above, where knowledge and cer­tainty touch between AB and B, and we have certainty However, it is vague whether it is a matter of knowledge. We do not commonly reason that we know the kind of proposi­tions that Moore lists because we take our reality for granted and assume that the objects around us are real. Truisms are fundamental such that everyone could claim them. If someone says, “I know that the world exists,” we take that person as being philosoph­ical or silly, but if someone contrarily claims, “I know that the world does not exist,” we think that the person is demented (Wittgenstein 1984, §155). Throughout his notes, he touches the subject of appearing like a madmen among normal people when doubting the established language games.

Wittgenstein criticizes that propositions of the kind “here is a hand” are not something we can know. Although Wittgenstein does not suggest that Moorean truisms are propositions that we ‘know,’ he recognizes that these have special status. They are part of our world-picture (Ibid., §162), the inherited background of a person who decides what false and true are (Ibid., §94). We do not commonly have to justify the basis of our world-picture.

We could create scenarios in which articulating “I know” those truisms makes sense because we would have to justify how we know them. Situations such as meeting aliens or wild tribes (Ibid., §162) and having philosophical discussions (Ibid., §467) are compatible with knowing truisms because then we would have to think about justifica­tion and evidence. If we are not dealing with the kind of unusual scenarios in which we can give grounds for knowing, then we misuse the words “I know.”

Wittgenstein asks whether “I know that that’s a tree” is different from “that is a tree” (Ibid., §585). They are not the same because in the first case, “I know” expresses a subject who is not just experiencing a tree, but asserting knowledge of the fact. In the second case, the person is not claiming to know, which is what we usually exclaim.

If Moore says, “I know that the earth existed long before my birth,” he is ex­pressing a statement about himself even ifit is also a statement about the physical world. For Wittgenstein, it is not philosophically interesting if Moore knows this or that, but that and how it can be known (Ibid., §84).


1 examine these regions in Section 3, but I first present the background by as­sessing Moore’s argument against idealism and skepticism. I then focus on Wittgenstein’s criticisms because Moore’s findings perpetuated after Wittgenstein criticized them. “Many philosophers (e.g., John Locke’s An Essay Concerning Human Understanding) pursue inquiries into the certainty of human knowledge (Locke 2008, §2). Immanuel Kant seeks to fulfill the conditions of certainty and clearness in Critique for Pure Reason (cf. Kant 2003, p. x).

2 In “esse is percipi” (Berkeley 2004, §3).

Excerpt out of 14 pages


The Relationship Between Knowledge and Certainty
Humboldt-University of Berlin
Wittgenstein’s Über Gewissheit
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Kommentar des Dozenten: "This essay is entitled ‘The Relationship Between Knowledge and Certainty’. It discusses Wittgenstein’s criticisms of Moore’s arguments and then explores some of the differences between knowledge and certainty. Good knowledge is shown of some of the key remarks in On Certainty and of some of the main issues."
Moore, Wittgenstein, Wissen, Gewissheit, Knowledge, Certainty, Über Gewißheit, On Certainty, A defense of common sense, Proof of an external world
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Valery Berthoud (Author), 2018, The Relationship Between Knowledge and Certainty, Munich, GRIN Verlag,


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