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Is it Possible to Doubt Everything?

Why is it not possible, if it is not possible, to doubt all things? Is the life of complete non-belief logically possible, e.g. is there a coherent description of Diogenes the Cynic as an absolute skeptic?

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty. (OC § 115)

The word 'doubt' is without meaning without its antithesis 'undoubted' or 'certain'. The doubt and that which removes the doubt. But can every doubt be removed, or are some irresolvable? Is it true that everything can be doubted, just not everything at the same time? Or are there things it is impossible to doubt? Say one's own existence and the principle of contradiction (in meaning)?

Note that there is a later and longer discussion of this topic, Why question everything?, with notes about Socrates, Descartes, Saint Augustine, the Apostle Paul, Cato the Elder and Voltaire.

These are old logic of language discussions. Logic of language: "How is language with meaning to be distinguished from language without meaning?" Why is there this concern in philosophy for language meaning? Because we have no tool in philosophy except language, not even undoubtedly our eyes and ears.

Outline of this page ...

Words that follow "Query:" led (or misled) Internet searches to this site. I have responded to a few here.

Absolute skepticism as a picture with no application

Is it possible to take nothing for granted, even the language we speak, to doubt whether there is any distinction between sense and nonsense?

Everything can be doubted, but not everything at the same time. "In every investigation, something must stand fast" (Drury). And so Diogenes cannot both doubt whether it is daylight despite the sun shining through his window and use a lamp to judge whether there is a man at his door. He cannot both doubt his eyesight and at the same time use his eyesight as his criterion of truth.

An investigation that tried to investigate everything at the same time would not be what we call an investigation. It would not have a leg to stand on.

We have an absurd picture of Diogenes the Cynic: "I see that the sun is now casting daylight; nonetheless, my eyes may be deceiving me about this, and therefore I will light a candle, although the light this casts may be an illusion as well. I may be dreaming, hallucinating, drunk, or ill. There are so many possible illusions and delusions that it is impossible not to doubt everything." However, when Diogenes says this, is he also doubting the meaning of the language with which he says it, e.g. the names of common objects?

Appreciating this objection, there was an absolute skeptic who chose to be silent and henceforth only silently jiggle his finger to indicate that he heard but would not reply. I can't remember his name; it may have been Cratylus [Aristotle, Metaphysics 4.1010a]. But how could anyone have come to know the reason for his silence?

"... he gave up utterance and used only gestures." (OCD 2e (1970), Etymology 2) According to what I have called Wittgenstein's logic of language, a gesture belongs just as much to language or convention as any spoken sound or mark on paper does; they are all linguistic signs. And therefore logically the skeptic ought simply to have remained impassive, because a gesture would have meant: "I hear your words, but your words may be mere noise." But if all language really is nonsense (undefined noises), then gesture is also nonsense, and if so, then why gesture? unless one imagines that it is not nonsense (meaningless).

Is it philosophical to classify as a doubt something we refuse to set or accept criteria for the removal of? Just as objective certainty requires grounds, so objective doubt also requires grounds. If we tried to apply the expression 'We can never know' to everything, would we be saying anything at all? (Objective = rational or having reasons. Philosophy is the rational search for knowledge or understanding in logic, metaphysics and ethics.)

In practical life only

"Is it philosophical?" One question is: what if anything would be the meaning of the absolute skeptic's language? According to Wittgenstein, language gets its meaning from its use in our ways of life; when that language is removed from that way of life, it loses its meaning, its meaning in Wittgenstein's selected sense of 'meaning', that is.

The limit of Wittgenstein

However, by the standard Wittgenstein set, what has always been called philosophy is not possible. Can philosophy really never be an investigation of phenomena (e.g. the riddles of existence), but only an investigation of how language is used in the practical life of the tribe?

The eternal questions without answers as a "form of life"

Is my understanding only blindness to my lack of understanding? It often seems so to me. (OC § 418)

That type of disquietude is certainly one of the things that makes someone into a philosopher. (Z § 455) But without reasons, 'seems' is the operative word.

The picture of the Greek absolute skeptics is not pointless, but its point -- i.e. the meaning of this picture -- isn't clear until we examine (question) it. "The picture is there, but what is its meaning?" (PI §§ 422, 424)

There is a skepticism that belongs to the puzzlement we feel about our very existence. "Am I blind to the most important thing?"

Does asking questions about "the riddles of existence" simply belong to the human "form of life" rather than to the intellect? According to Wittgenstein, these riddles do not state hypotheses; they are not questions that are answerable by an examination of the facts and so, at least in this respect, life's riddles without answers resemble religious questions. And about those questions, Wittgenstein says that they are not really questions but instead "pictures", for the religious believer life-guiding "pictures" (e.g. life after death, a last judgment, evil as what God condemns).

But just try to describe how "absolute skepticism" could be used as a life-guiding picture. Could anyone really live like the Diogenes who lighted his lamp in broad daylight, doubting everything all the time.

A dog is not puzzled by existence. Much less a cat. Such puzzlement simply does not belong to their forms of life -- i.e. such language applied to them is undefined in meaning: what would we mean if we said that a cat was contemplating the morality of killing for sport rather than hunger? or that a dog was pondering the mystery of its existence? If we could teach a dog to speak, could we teach it to speak about that? (PI II, xi, p. 223)

Is it possible to doubt everything? The limit of investigation

... in every investigation there will always be that which is not itself investigated; in every experiment there will be data which are not the result of experiment; in every enquiry there will always be that which is not enquired into. (Drury, The Danger of Words (1973), p. 72; cf. OC § 337)

In every investigation, there are things that are treated as axiomatic. Drury meant: which cannot be investigated because the word 'investigate' would be undefined. For example, a statement like 'I doubt that it is possible to remember anything' is nonsense, because it depends of memory and language to even be made. The limits of memory can -- i.e. this combination of words is defined -- be investigated; one may have doubts about the reliability of memory, and experience -- what else -- both confirms and refutes those doubts: but such an investigation depends on memory not being completely unreliable, just as the investigation depends on all language not being meaningless (The limits of distinguishing sense from nonsense can be investigated, but not if all language is meaningless). Cratylus's position amounts to this: all language is meaningless -- but that could neither be thought (said to oneself) nor communicated (said to others) if it were true.

Query: what happens to thought when you doubt everything?

If to think is to use language (Theaetetus 189e-190a), or, rather: where thinking is to use language, to doubt everything at the same time would be to make rational thought and deed impossible. That would be what happens to thought.

Query: is it impossible to be skeptical about everything?

Levels of skepticism. In philosophy: "I am talking about something deeper than that", a deeper skepticism, skepticism about all human knowledge, not a practical skepticism which has limits of sense and nonsense (grounds for doubt and for the removal of doubt) to answer to, but doubt about the ability of man to know anything that is not relative to the human way of knowing. Within the limits of his nature, man knows many things, although not what's most important -- but only within those limits. That type of skepticism cannot be resolved, because there is nothing that we would call a 'resolution' here; it is a question without an answer: is reality confined to what is perceptible to the five senses and to the way the five senses perceive?

Query: is it possible to doubt that anything at all exists outside the mind?

Descartes held that we can apply "hyperbolical doubt" to the existence of external things, although "he also maintained that reason can overcome this doubt". (Copleston, A History of Philosophy, Volume VI, XII, 9)

Doubting everything at the same time would be "hyperbolical" if it were not impossible. By 'hyperbolical doubt' Descartes meant doubting something that no one doubts although it is possible to doubt it.

Query: how do we know that things we cannot see both past and present actually exist or existed?

(1) One topic suggested by that query concerns the human way of life: "How do I know that the history I was taught at school is true or that places I have never been to exist?" The short answer is that I don't know. I believe. That's the way we are trained to think in school in Western civilization from childhood onwards. It would be hyperbolic doubt were we to doubt what we were taught about geography or that there was a Second World War, for example. (2) Another topic the query may suggest is a question Bertrand Russell asked: "How do you know that the world and all your memories of it did not spring into existence 5 minutes ago?" To give a meaning to that question seems to require the introduction of the picture of a god-like being who sees what man cannot see.

"Question Everything" (Descartes)

Query: question everything. Descartes.

In the The Gulag Archipelago there is a story Solzhenitsyn told: "You're a mathematician. What did Descartes say: Question everything." -- "But what did that mean -- everything? Surely not everything." (Descartes was not only a philosopher, but also a mathematician and physicist.) But Descartes did not undertake, as Socrates did, an examination of everything in order to distinguish what he knew from what he only thought he knew (but did not) for its own sake. Instead, Descartes had a specific reason for his method in philosophy to begin by questioning everything.

"Question everything." Descartes' project in philosophy was to find something that he could not doubt, and to use that as the foundation on which to build his own system with the same a priori -- i.e. independent of any doubtful experience of the world or authority -- certainty as the certainty he believed he found in mathematics, using the deductive method of mathematics.

It may easily look as if ... secure understanding is only possible if we first doubt everything that can be doubted, and then remove all these doubts. (PI § 87)

The story is more in the spirit of Socrates than of Descartes, because the point of the story is to question all systems. Without exception. And Descartes did not question whether the deductive method of certainty of mathematics was also valid in philosophy and physics. About logic he implicitly had no doubt (although it may also not be possible to doubt that).

What did Socrates question?

Query: question everything. Socrates.

But note that Socrates' questioning was only in ethics (in Plato's "no small matter, but how to live"); he used logic as his method or tool in trying to discover what the good is for man and to live accordingly. (All rational philosophers have used logic, although not with Socrates' originality.) Socrates did not ask questions like "How do I know that I am now in Athens and not rather on the moon?" and "How I do I know that I am now awake rather than asleep?" The question "Is it possible to doubt everything?" was not Socrates' question as it was Descartes'.

Absolute skepticism (Pyrrhonism)

Skepticism is not irrefutable, but palpably senseless if it would doubt where a question cannot be asked. For doubt can only exist where there is a question, and a question only where there is an answer ... (TLP 6.51, tr. Ogden)

A rational doubt can only exist where there are grounds for doubt and where what would remove the doubt is defined.

And neither a question nor the criteria for an answer is possible if the question cannot be put into words that are not nonsense. An assertion of doubt where there are no grounds for doubt, if not meaningless is irrational; but philosophy is rational, although the raw material of philosophy need not be rational. (The root of 'rational' is reason, and reason =logic.)

Remember always that "there are many ways to cut a pie", not just one, but we might distinguish between objective and subjective (or, rational and irrational) doubt. By 'objective doubt' we can mean doubt where there are grounds for doubt and criteria for the resolution (removal) of the doubt -- resulting in a true or a false proposition. But by 'subjective doubt' we can mean doubt where there are no grounds for doubt, but where there is discomfort, wariness or unease about accepting that a given proposition is true (or, alternately, false) despite there being no reason not to accept it. (But then we might want to say that there is also a third category, namely "philosophical doubt" which it is impossible to resolve, consisting of imagining a deity who sees what it is impossible for us to see and therefore sees that we are deluded about or ignorant of the truth of this or that proposition.)

If everything speaks for it, nothing against it ... (OC § 191)

Well, but isn't that what we call 'certainty', what everyone means by that word? Isn't it what we call the absence of grounds for doubt (TLP [6.51]: "if it would doubt ...")? But we don't call the absence of grounds for doubt knowledge. Knowledge is positive: it requires sufficient grounds, not merely the absence of grounds for doubt. (I am talking about the concepts (rules for using words) 'knowledge', 'doubt' and 'certainty', of course, not as it were about the phenomena, trying to guess their essences as Plato does)

"The truth is not determined by taking a vote" (Plato versus Aristotle)

Query: Descartes said a thing is not necessarily true because it is uncontested, not controversial.

A proposition is not true just because no one doubts it, but is that the end of it? Why does no one doubt it? has to be asked. Is it because it does not occur to anyone in a particular tribe's way of thinking to doubt it (a philosopher is an outsider), or because no one sees a way to doubt it, i.e. no reason (identifiable grounds) to doubt it? But consensus ("lack of controversy") is not logical necessity, and it is irrelevant to truth and falsity -- although Aristotle had a different view about the place of consensus in philosophy.

The foundations of the moon

Query: why is it not possible for me to doubt that I have never been on the moon?

Many things might be said in response to this query. The following are only a few.

In what context is it "not possible"? You can't -- and this is a remark about the grammar (in Wittgenstein's jargon) of the word 'doubt' -- just doubt things out of the clear blue sky: a doubt requires a context, just as a statement of fact or any other bit of language does: words are tools that only have meaning, according to Wittgenstein "in the flow of life": it is what we do with words that gives the words meaning. If there is no context, then the query's words 'not possible' mean 'this is undefined language', i.e. nonsense, words, sounds uttered apropos of nothing.

What misleads us is that the combination of words is not meaningless in the circumstances in which it has a use -- or in which a use could be invented for it by imagination ('logically possible' means 'describable') -- in the language. But the combination of words is meaningless if this is not one of those circumstances: 'meaningless' = 'undefined in this particular context, not in every imaginable context'. (Meaning, falsehood, and use in the language.)

Why can't I doubt the truth of the proposition 'I have never been on the moon'? First, rational doubt requires rational grounds for doubt. Here the "cannot" does not mean: I cannot imagine circumstances where I might have grounds for doubt. I can so imagine, but those circumstances do not belong to our normal life, and it is in the context of our normal life that we make use of language.

The procedure of putting a lump of cheese on a balance and fixing the price by the turn of the scale would lose its point if it frequently happened for such lumps to suddenly grow or shrink for no obvious reason. (PI § 142)

That if is counter-factual.

And second, I cannot doubt that proposition's truth without calling into question the truth of all the other propositions stating my fundamental beliefs about reality (my "world-picture"). They are the foundation of all my thinking about reality; they are bedrock (There are no grounds beneath them). (Metaphysics is a "speculative position" -- it is not our normal world-picture, but a critique of it using imagination.)

"I cannot doubt that I exist, because I must exist to doubt." (Augustine)

Query: is it possible to doubt everything?

Was Descartes wrong -- is it possible to doubt that "If I think, then I exist"? Or is it not possible to doubt everything?

Should anyone philosophize?

For a time Samuel Johnson used a dial-plate for his watch with this quotation in Greek:

The night cometh when no man can work.

But he set this dial-plate aside, feeling that his watch was too public and therefore pretentious a place for it. (Boswell, The Life of Dr. Johnson, 1768.Ætat.59)

"We must work while there is still light." Doubting all things, questioning everything (the examined life of Plato's Apology) is the work that we must do, according to Socrates. It is the path to "knowing yourself", to not thinking you know what you don't know -- to knowing what the good is for man and how to live your life accordingly.

The difficulty is to take nothing for granted, if that is possible. That is in any case what philosophers want to do.

Query: why should you question everything?

The discussion of that slogan takes this form: "Question everything!" -- "Why?" -- "Exactly." And the philosophical form of the query is instead: "Should you question everything?"

What do we mean by 'understand'?

Note: this supplements the discussion: What did Wittgenstein mean by "Forms of life"? (There is also a later discussion of the concept 'understand' which distinguishes between various senses of 'to understand'.)

Query: how do people who are born deaf form their thoughts?

How do we apply the word 'thoughts' to a born-deaf person? Do we imagine born-deaf persons as human beings who do not use language to think? And if we are deaf ourselves, do we already know the answer to this question? Do we call one thing 'thoughts' for a hearing person, and something else 'thoughts' for a born-deaf person?

Does a born-deaf person think in sign-language, moving their hands as a hearing person uses their voice to think out loud? Or do they move their hands in their minds the way hearing persons talk silently to themselves? And about a born-deaf person who has never learned to sign or is illiterate -- does that person have thoughts, thoughts without words?

How is a hearing person to answer that question? One way is by observation of the behavior of born-deaf persons, although that may not tell us too much about a person's inner life. Another way is by examining the verbal testimony of people born deaf (or who became deaf at a very young age as Helen Keller did)?

Can we say that when a born-hearing person asks about a born-deaf person's thoughts that he understands his own question? Or in this case do we have to assign a meaning to the word 'understand' in the context of the phrase 'born-deaf person's thoughts'? In other words, do I understand the question without further explanation? By analogy I do (how else).

What do I know about anyone else's thoughts -- what do I know about anyone else's soul? What I know is our agreement in the language we use (PI § 241) and in our behavior.

I am asking this question from a logical (i.e. language meaning, where the rules for the use of words in the language are public, the same for everyone) point of view, not from a scientific one, although what a theory of natural science would look like here, I don't know.

Mr. Ballard (philosophical thoughts without words)

"How do born-deaf people who have not learned language think about things?" What do we call 'thinking about things' in the case where language is not used to think? Wittgenstein cites the case of Mr. Ballard, who is quoted by William James, that he had had thoughts about the origin of existence and God before he had learned any language (PI §§ 342-349). Do I understand Mr. Ballard? We know what thoughts about existence and God are when they are put into words, but without words ... So on the one hand we understand, but on the other we don't -- i.e. show us an example of a philosophical thought not expressed in language.

Query: physiological location of the mind.

There are two parallel vocabularies here, the psychological and the physiological. The word 'mind' belongs to one, 'location' to the other, and parallels do not intersect. On the other hand, what harm does it really do if we reply, "the human nervous system"? Doesn't that depend on what consequences are going to be drawn from this identification, e.g. "brain dead" = "soulless"?

Remember what Drury, who had to deal with such cases, wrote about "the dependence of mind on body" (The mind and its place in nature), all the reservations he had which he believed could never be resolved. (Maybe, after Kant, it should be "Nature and its place in the mind.")

From the point of view of the logic of language, the combination of words 'physiological location of the mind' is nonsense: the word 'mind' is not the name of an object and 'location' ["location-grammar"] is only applied to objects, and what would 'physiological' contrast with here?

Might not someone object that some day natural science may be able to answer the question about the location of the mind? The reply is that here the only limit of science is concept-formation, which means that in order to answer the query's question it would be necessary for scientists to revise the concept 'mind' (i.e. redefine the word 'mind'). Because no discovery of further facts can answer a question that consists of an undefined combination of words, i.e. nonsense.

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