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What is Truth?

Philosophical Reflections XXVI

In Philosophical Reflections 25 we looked at inductive reasoning, including why it is valid and gives true knowledge. Now we will take a closer look at the nature of truth: what we know versus what is, and how certain we can be of our knowledge.

Fear, Uncertainty & Doubt

Induction is the source of all our knowledge. It is a process of generalisation from particular instances, usually when not all instances have been or even can be observed. This incompleteness is a necessary consequence of our nature as finite beings, who can only gain knowledge through physical senses and be in one place at one time. This "limitation" is often the basis of such claims as "we can never be certain of anything." But as I have shown, this is not true: valid conclusions of induction are certain within the context from which they are derived.

It is the limitations of context which limit our knowledge. Perhaps a thing will behave differently under circumstances we haven't encountered. But even that limitation is mainly a feature of descriptive induction. The power of explanatory induction is in predicting new behaviours. Indeed, science progresses by successfully predicting what will happen under new circumstances! There might still be things we don't know: but they can never refute what we do know, merely add to it by placing it in a wider or different context.

When discussing certainty, it is worth considering what is meant by that term. Few things are certain in an absolute or metaphysical sense, that is, true because they must be true by the nature of existence. That you exist and an external reality exists are absolutes confirmed by every thing you see and do; "A is A" and its implications are absolutes, as whatever the nature of a thing, that is its nature. But all particular knowledge about the things which exist in reality is derived by induction from the evidence of our senses, and can never be an absolute – so long as it is not metaphysically impossible that we have missed a wider or more fundamental context.

However, to wish for absolute certainty is itself to want the metaphysically impossible. As shown in Philosophical Reflections 24, all knowledge is finite and is acquired by the application of reason to our senses: automatic omniscience is impossible in the real world. To say, "Induction isn't good enough! I demand certainty or nothing!" is to say, "I demand that reality be something it is not!". And were you to practise this policy consistently, it is indeed "nothing" which you could achieve, and would soon become.

Ironically, demands for absolute certainty often cloak the desire to escape the requirements of what we do know, as if denying certainty justifies denying knowledge. Hence the spectacle of Immanuel Kant limiting knowledge to make room for faith and a mystical morality of Duty. Hence the spectacle of those who deny certainty yet demand that governments have the right to rule people by force in order to impose on them "the good" – in their view. Understanding the nature of certainty is an important exercise: as these examples show, ethics do not exist in a vacuum, but grow from your metaphysics and epistemology.

True or False – or Neither

Metaphysics pertains to reality, to what is: and what is, is, whether we know it or not. Epistemology pertains to our knowledge and therefore to the relationship between consciousness (us) and reality (that about which we wish to know).

Knowledge and beliefs consist of propositions about reality. "Iron is hard." "Wood burns." "You can't breathe water." "The stars are distant suns." "All men are mortal." "God exists." "There is no God."

When evaluating a proposition, what we want to know is how it relates to reality. But we can only evaluate that in the context of how we know anything: in the light of reason applied to the evidence of our senses. It is critically important to remember that there is no other way to evaluate the truth of a proposition. It means that there are more possibilities than just "true" and "false". Depending on the evidence available to us when we evaluate a statement, it can be true, false, possible, arbitrary or meaningless.

The true is that which corresponds to reality. To say we know it about reality requires a certain level of evidence. That is, to be called true a proposition must be provable by reference to the facts of reality. For example, "Mars is a planet orbiting the Sun."

The false is that which contradicts our knowledge of what exists, by denying that which is or asserting that which is not. The false is the converse of the true, and requires the same level of evidence: to be called false a proposition must be disprovable by reference to the facts of reality. For example, "The moon is made of green cheese."

The possible is that for which there is some evidence, but not enough to be sure (or the evidence is contradictory): the proposition is worthy of consideration and further testing, but in the context of present knowledge is neither true nor false. For example, "There is intelligent life outside the Solar System." The possible spans the range from probable to improbable.

The arbitrary is a claim, denial or doubt without any evidence. Precisely because there is no evidence, the arbitrary is outside the realm of knowledge: it is neither true, false or even possible. True, false and possible have cognitive content: they are based on reality and tell us something demonstrable about reality, being induced from reality. But the arbitrary by its nature has no link with reality, it is just made up at a whim, and therefore has no cognitive content and must be ignored (for more on the arbitrary, see my discussion of "empty doubt" in Philosophical Reflections 7). For example, "There are undetectable aliens in this room."

The meaningless is a statement which by its nature cannot have any referent in external reality. Even the arbitrary at least purports to be about reality, whereas the meaningless lacks even that. This is the preserve of self-referential paradoxes, discussed further below.

The Arbitrary Cannot Be True

A deeper analysis of the nature of the arbitrary is worthwhile, as lending credence to arbitrary claims is a common pitfall. The proponents of the arbitrary generally argue that their claims are possible because you "can't disprove it": when in fact the arbitrary is worthless.

Remember that true, false, possible and arbitrary are always and can only be judged in the context of present knowledge – by the nature of knowledge. Clearly, a proposition which is possible in one context can be true or false in another context of greater knowledge. But equally, a proposition which is arbitrary in one context can be true, false or possible in another. Consider the statement: "Jupiter has more than 10 moons". In the context of present-day knowledge, this is true; but if made by an ancient Roman, it would have been arbitrary. This contextual nature of truth is how an arbitrary claim can appear to be possible. But saying the arbitrary is "possible" because it might be possible in some other by definition unknown context, is just a further arbitrary claim: there is no such context to which one can point. If there were, the original claim wouldn't be arbitrary.

In most cases, a claim you hear for which you know of no evidence is arbitrary in your own mind – even if it is true in the context of knowledge you don't have. The correct response to such claims, assuming you care enough to find out their truth, is to ask, "What is the evidence?" Only then can you judge whether the proposition is true, false, possible – or arbitrary even in the claimant's mind.

Some propositions are inherently arbitrary: there can be no evidence relating to them even in principle, for example Kant's undetectable "noumenal world" and the statement "There are invisible aliens in the room whose technology is so advanced that we can never detect them by any means." In such cases, you don't even have to ask what is the evidence, because the claimant himself admits there can't be any.

Think Positive

The above relates to an important principle: knowledge is positive, not negative. All knowledge is based on the observation of things that exist, not on the non-observation of things that don't exist. Knowledge consists of understanding the qualities of that which exists. That which doesn't exist both has no actual qualities, and can be assigned an infinite array of contradictory imagined qualities.

Thus the definition of "possible" is not "cannot be disproved": it is "some evidence exists that it is true"; the definition of "true" is not "cannot be disproved", but "can be proved"; and the definition of "false" is not "cannot be proved", but "can be disproved".

The arbitrary and the meaningless clearly have no place in such knowledge. There are no positive existents to anchor them to reality.

About Me

Above I noted that some statements are not about reality and are meaningless. This special category is the home of self-referential paradoxes.

A self-referential paradox is a statement which if it is true must be false but if it is false must be true. For example, "This statement is false", or "This sentence has exxactly two errors." Such statements say nothing about reality, and can never say anything about reality. Therefore they are neither true nor false, but meaningless. They are the "black holes" of knowledge – forever cut off from anything but themselves.

Some people see deep significance in self-referential paradoxes because they think propositions must be true or false. But as we've seen, true and false pertain to statements linked to external reality by evidence. Self-referential paradoxes lie outside that, and therefore have no link to truth or falsehood, and no significance with respect to knowledge about reality.

For further analysis of the kind of inflated claims made about self-referential paradoxes, versus their real status, see Philosophical Reflections 4 on Goedel's Theorem, which concerns the supposed implications of self-referential paradoxes in formal mathematics. Note that Goedel's Theorem and the like have been used in some areas of mathematical investigation to apparently lead to meaningful conclusions, for example in the fields of computational analysis (e.g. theorems on whether you can analyse a program to see if it ever comes to a conclusion). However this "success" is not because of some deep meaning in these theorems: rather, showing that some mathematical process contains or requires a self-referential paradox invalidates it automatically, because it cannot then be linked to reality. A proper epistemology which recognises the meaninglessness of self-referential paradoxes shows both the shallowness of Goedel's theorem, and the defectiveness of algorithms which resolve into or depend upon self-referential paradoxes.

Living Certainty

The purpose of philosophy is life – because life is the purpose of all knowledge. This is why claims that induction is flawed because it is not "certain" are beside the point – and hypocritical. It is not absolute certainty that matters – to anyone.

Consider the history of man and why we needed and need knowledge. Can I eat this? Is that poisonous? Is this creature useful or dangerous? What causes disease and how can I cure it? How can I make a tool to obtain food? How do birds fly and can I do the same? Can I breathe underwater? How can I cross this river? How can I cross the ocean? Some knowledge is purely curiosity-driven: but that just puts it back a step. We are curious for a reason rooted in our nature as human beings – that learning and knowledge are critical for life and the achieving of values. And achieving values is the means and end of life.

Because of this, every person living must learn and act upon such knowledge, or die. Every person, even philosophers who claim there is no reality or if there is, you cannot know its nature: and that simple fact is enough to demolish their entire edifice. Anybody who claims that reality is unknowable yet objects to being locked in a dungeon without food or water is lying.

It is not certainty that matters, because the purpose of knowledge is not the satisfaction of some wish for omniscience, nor the fulfilment of a rationalist's desire to know the universe without having to look out the window. The purpose of knowledge is this: to live we must act, to act we must know how to act, and to know how to act we must understand the nature of ourselves and the world around us. That is the purpose of knowledge and that is the criterion of valid knowledge.

Induction meets that criterion and achieves that purpose.

© 2003 Robin Craig: first published in TableAus.