For religious believers, the importance of arguing that religious language refers to something and is thus meaningful is obvious.  Without meaningful language, religion becomes difficult.  Faith may well be possible without formal, positive doctrine or liturgy – as the silent worship and commitment of members of the Society of Friends demonstrates – but without the ability to describe beliefs in religious doctrines it is difficult to hold a religious community – let alone a religious denomination – together for long.  The multiple splits in the Quaker community and the diversity that still characterizes it is evidence of this.   Plato and Aristotle understood words to be signs, pointing towards meaning beyond themselves.  For Plato, ultimate meaning was metaphysical in the forms, which we recognize through reason as reflections in the world around us.  For Aristotle, the forms exist within human reason itself, but they still exist for words to point towards.  The central problem with religious language is that if religious words are signs, they point towards something that we cannot see, hear, touch, smell or taste… nor even understand in a complete way.  Can a sign which points towards nothing determinate really be understood as a sign at all? If language is seen in this traditional way, then religious language must be meaningless, and yet this is not the only way of seeing language.  

For David Hume, human knowledge is much more limited than it first seems.  Knowledge based on sense-experience is more certain than that which is not, but even the senses can be misleading.  A red ball is not really red, but is just perceived as such by the rods and cones in our eyes, which are stimulated in a way that our brains usually interpret as red by the particular wavelength of light that the ball reflects. Yet Hume agreed with Locke that the only way that the philosopher can progress is to cut away the undergrowth of assumption and conjecture, identifying the few relatively certain propositions and concentrating on those.  This critical approach to philosophy inspired Immanuel Kant, who in the “Critique of Pure Reason” (1781) divided all claims into three categories

1. synthetic claims which are supported by observation and provide new knowledge, albeit of a quite limited variety (this ball is red, geese honk loudly, crisps are salty)
2. analytic claims which refer to logical relationships between terms and provide no new knowledge, although they clarify and support understanding (2+2=4, an unmarried man is a bachelor, a triangle has three sides)
3. meaningless claims which refer neither to observable things nor to logical relationships between terms.

For Kant, it is impossible to speak meaningfully about God.  The arguments for God’s existence all fail because human knowledge is rooted in our phenomenal experience and claims about what lies beyond it in the noumenal realm, including about God, are just speculation.  The most human beings can do, argued Kant in “Religion within the Bounds of Reason Alone” (1794) is to POSTULATE God’s existence as the best explanation of order and the necessary reason to trust in the fairness of the universe and carry on trying to do what it appears we cannot do… be good.

Kant’s critical approach to knowledge was highly influential, but it rests on some very big assumptions and (arguably) needs to stretch the limits of knowledge beyond breaking point by its own definitions in order to work.  Firstly, American logician WV Quine attacked Kant’s “Two Dogma’s of Empiricism” in 1951, pointing out both the difficulties in relying on sense-data (Descartes previously described these in the 17th century) and the fact that Kant and the later logical positivists accept logic as a form of knowledge and as a means of refining and interpreting sense-data without real argument.  What makes unquestioning faith in logic and assumptions about things being the way they appear to some people’s senses better than unquestioning faith and assumptions about other things?  Secondly, Kant’s system needs the postulates of God, freedom and immortality to work… none of which can be known to exist by Kant’s own categorization of knowledge and against how things appear to most people.

• Human freedom seems to be constrained by everything from social norms to genetics, yet Kant has to suppose that people are free both in order to support the credibility of reason and the demand of the moral law.
• The evil and chaos in the world speaks against the existence of God and yet Kant has to postulate God to explain the order he needs to believe exists in order that reason and morality retains credibility.
• Finally, there is no observable or logical evidence for an afterlife, yet Kant has to suppose that one exists or he cannot hang on to order in the universe, on which reason and the credibility of the moral law depends.

In the end, Kant relies very heavily on things that can neither be proven nor even supported through experience in order for his critical system to work.  Although Kant raises serious questions about the possible meaningfulness of religious language, the force of these questions is taken away by the cracks in the foundations of Kant’s critical system.   

Nevertheless, despite the problems with Kant’s critical approach to knowledge and language, through the 19th Century philosophers were heavily influenced by it.  Gotlob Frege drew heavily on Kant in his work on Logic, which went on to inspire the work of Russell and Moore (and Russell’s protege Wittgenstein) in pre-war Cambridge, as well as Viennese philosopher-scientists Otto Neurath and Moritz Schlick and their “Vienna Circle”, which started to meet in 1921.  Seeking advance understanding, Schlick brought Mathematicians, Scientists, Psychologists and Philosophers together to follow on from work done by Russell, Moore and Wittgenstein in establishing the nature and limits of human knowledge. Starting with Kant’s distinction between synthetic, analytic and meaningless claims (and inspired by Ludwig Wittgenstein, who had argued that “of that which we cannot speak, we should be silent” at the end of his first work the “Tractatus Logico-Philosophicus” (1921)), Schlick proposed that a “Verification Principle” should be used as a test of meaning – claims that are not in-principle verifiable through the senses (i.e. claims that cannot be physically checked) or which are not related to the logical relationships between terms should be labelled meaningless and excluded from academic discussion.  Because of this, during meetings of the Vienna Circle, discussions were strictly focused on what can be known… an adjudicator was even appointed to prevent discussions straying into speculative metaphysics by making claims about such matters as… God.

Partly because the Logical Positivism of the Vienna Circle were published in a Manifesto in 1929, and were of unusual political interest, Schlick’s ideas were influential.  In Oxford, following a visit to Vienna instigated by his tutor Gilbert Ryle, AJ Ayer developed and refined the Verification Principle in “Language Truth and Logic” (1936), the same year in which Schlick was murdered by a former student who claimed (at his show-trial) that Logical Positivism had “interfered with my moral restraint”.  The book was reprinted after the war and caught the mood of the times.  After the discovery of Hitler’s crimes and the dropping of nuclear bombs on Hiroshima, it was difficult to hang on to any belief in God or moral absolutes!  Logical Positivism dominated Philosophy into the 1950s, with its exclusive focus on what can be known through science and mathematics and its relegation of topics outside these spheres – moral philosophy, aesthetics and religion – to junk-status. Nevertheless, despite the popularity of Verificationism it failed to show that religious language is meaningless. This is because…

1. Verificationism rules out many areas of academic discussion along with theology and religion.  The consequences of not being able to discuss morality meaningfully were thrown into sharp relief when Schlick’s Nazi student Johann Nelbock shot him on the steps of the university.  Nelbock claimed that Schlick’s teaching had “interfered with his moral restraint” and maybe he had a point.  If Schlick (and Hume and Ayer) was right and morality depends only on sentiment, personal emotion and preferences, then it is difficult to argue that Schlick’s murder was wrong – especially on the eve of the Anschluss when Nazi ideology was incredibly popular in Vienna.
2. Ayer was forced to accept that many fruitful forms of academic discussion are not even in-principle verifiable.  Historical events cannot be verified except through secondary sources.  Some scientific questions are not open to verification – for example, quantum events cannot be observed accurately because the act of observation affects the event.  In additio, as Thomas Kuhn and Norwood Hanson pointed out, no observation is ever entirely neutral, no matter how “scientific” it might appear.  We interpret what we see through an accepted paradigm… maybe we only actually see what we want to see…  As the great Art Critic John Berger argued in “Ways of Seeing”, seeing is avowedly political rather than scientific and neutral.
3. As Verificationism cannot itself be verified it is a self-defeating theory that fails to mean its own standard of meaningfulness. 

Verificationism lacks credibility as well as practicality as an approach to defining meaning in language generally, so its attack on meaning in religious language must fail.  

Verificationism was definitely in decline by the 1950s, but it was replaced by the Falsificationism proposed initially by Karl Popper and rooted in scientific method.  Falsificationism suggests that the meaning of a claim depends on being able to define circumstances in which the claim could be falsified.  Scientific claims such as “all swans are white” are meaningful, not because they can be verified – and they cannot be, because even without black swans, the total population of swans through history is never going to be available to check – but rather because we can describe a situation in which the claim would be shown false… such as the discovery of black swans.  Falsificationism presents a more serious challenge to the meaningfulness of religious language than either Kant’s critical approach to knowledge or verificationism because it goes against the nature of faith to describe circumstances in which faith will be falsified.  John Wisdom’s parable of the gardener was used by atheist Anthony Flew to make this point.  Two people look at the same patch of land – one sees the weeds and claims that it is uncultivated land and another sees the shadows of paths and claims that it is a garden whose gardener is on holiday.  Assuming the gardener never shows up there is no way that either person will change their claims about what they see.  Flew claimed that Religious faith is like this – unfalsifiable and therefore meaningless.  A believer looks at the world and sees God’s fingerprints all over it… they will never accept that there is no God, even when they see a film about the Holocaust, when their pet dies in agony or when they themselves have a run of undeserved bad luck.  The believer will always explain away things that go against their belief rather than accept that the belief has been falsified.  In Psychology this would be called confirmation bias – people tend to see things that agree with their world-view and ignore or explain away things that challenge their worldview.  As Kuhn, Hanson and Berger said, no observation is neutral.  Flew definitely has a point.  Religious claims – at least those made by most ordinary believers – are often unfalsifiable.  Attempts by John Hick and Richard Swinburne to argue that religious claims are in principle verifiable and falsifiable with reference to the afterlife are unconvincing. 

Yet despite the fact that religious claims such as “God exists” or “Jesus loves me” are often unfalsifiable, it is possible that other forms of religious language retain meaning of a different sort.  Ludwig Wittgenstein rejected the traditional view of words as signs, pointing towards a meaning beyond themselves, and argued instead that meaning comes from the way in which words are used.  Language is like a game; you can only understand somebody if you understand the rules of the game they are playing.  What it means to score a goal in football and in netball are different – and knowing the rules to one game will not help you to understand a conversation about the other.  Similarly, understanding religious language depends on knowing the “rules” of the religion, denomination, community or even smaller group within which that language is being used.  For Wittgenstein, and later for Anti Realists like DZ Phillips and for some Postmodernists, meaning depends not on what words correspond to, but on what they cohere with.  It is possible for the same religious claim to be true within one form of life and yet false within another.  Jesus rose from the dead is true for Christians and false for Muslims at the same time, regardless of whether the resurrection actually happened or not.  Compare religion with the famous “Schrodinger’s Cat” experiment.  After 5 minutes, nobody knows whether the cat is alive or dead… for Wittgenstein it is as meaningful to say that the cat is alive as that the cat is dead – both are true just as surely as both are false or one is true and one is false.  For anti realists in religious language, words cannot be understood as simple signs, because they point towards a God who is “other, completely other” (St. Augustine), “radically other” (Karl Barth) and “neither something nor nothing (St. Thomas Aquinas).  The meaning of religious language cannot depend only on what it refers to; it also depends on the effects it has on human beings and their spiritual state. 

Maybe, as Paul Tillich suggested, religious language is symbolic rather than built up of simple signs.  Religious claims participate in the meaning they refer to rather than just point towards it.  In a very real sense repeating the words becomes and defines a world of faith rather than creating it.  Religious language is necessary to religion in the way that God is necessary to the universe – not just as a cause in fieri, the words giving rise to a belief that can continue with or without the words – but as a cause in esse, the words sustaining the belief and its object in being.  In a way, this is what Iris Murdoch gestured towards in her version of the Ontological Argument.  She used the analogy of a tooth, venerated for centuries as a relic.  It may have been a dog’s tooth, but in the light of sincere veneration it begins to glow.  As Murdoch and before her Karl Barth recognized, the success or failure of the Ontological Argument does not depend on whether it is valid or sound.  Its true value is as a spiritual exercise, forcing the believer to reflect on the nature of existence itself and in so doing growing closer to a spiritual understanding of God’s necessity if not to an analytical proof of it.  Reflecting on the nature and possible meaning of religious language is a similar exercise.  While it shines a light on the difficulties in taking religious claims at face value, it also exposes wider difficulties in human beings making any claims to knowledge… and so brings people closer to appreciating the necessity of God.