Journal & Proceedings of the Royal Society of New South Wales, vol. 151, part 1, 2018, pp. 28–38. ISSN 0035-9173/18/010028-11 Rationality and post-truth — the threat to democratic society Donald Hector AM PhD FRSN The Royal Society of New South Wales Corresponding author. E-mail: [email protected] Abstract Two-thirds of Americans get at least some of their news from Facebook and over half get some of their news from Twitter. What has happened to reason? The post-modernists and relativists are in the ascendancy. The great Enlightenment philosopher David Hume said that errors in religion are dangerous but that errors in philosophy are only ridiculous. That is not the case. Rejecting established sources of reason and accepting that belief should have equal sway with fact puts an open, free society in great danger. This paper examines two issues: what is meant by the words “is true”? And the criteria for truth — how can we establish whether something is true or false? The situation is further complicated by the cogni- tive processes humans used to consider these issues. To determine whether a judgement, a choice, or a decision is likely to be successful, there are two to things consider. First: is the judgement rational — that is, is it coherent with the prevailing paradigm? and second: is the judgement accurate – does it cor- respond to established, accepted facts? Both are necessary for a sound judgement to be reached but neither is sufficient. But human cognition is flawed – our rationality is bounded and this can lead to serious errors. Bringing these two subjects together – philosophy and cognitive psychology – can give some insight into the nature of post-truth and the implicit threat to our open, democratic society. Introduction dangerous but errors in philosophy are only hat a mess! Why can’t people be sensi- ridiculous. That is not so. Rejecting estab- Wble! Wherever we turn, there are astrol- lished sources of reason and accepting that ogers, homeopaths, conspiracy theorists, belief should have equal sway with fact puts miracle workers and anti-vaxers. Politicians an open, free society in great danger. prefer to follow their “gut instinct” rather The advances made in human civilisa- than evidence-based rationale. The internet tion in the last 600 years have been greater has made everyone an expert! Two-thirds of than in the previous 60,000. In 1840, there Americans get at least some of their news was no country in the world where the life from Facebook and over half get some from expectancy at birth was greater than 40 years. Twitter. How much substance can there be in Today, just 180 years later, there is no coun- 140 characters? Is it the case that only twits try in the world where life expectancy is less tweet? Are the post-modernists and relativ- than 40 years — there are several countries ists in the ascendancy? What has happened where now it is more than double this. The to reason? rediscovery of Greek philosophy during the The great Enlightenment philosopher Renaissance, the emergence of the scientific David Hume said that errors in religion are method, mathematics, flourishing art, music 28 Journal & Proceedings of the Royal Society of New South Wales Hector — Rationality and Post-Truth and literature together brought about the emotion and personal belief. One might be agricultural revolution, the scientific revo- tempted to say that Twitter trumps fact. lution, the Industrial Revolution and an I will discuss truth and then examine extraordinary period of human creativity. Of rationality. Then I will briefly outline why I these the scientific revolution was the most believe post-truth is so dangerous. important because it changed the fundamen- But, first, I will make three statements tal paradigm of Middle Ages Christianity upon which my subsequent remarks are and the ancient world: belief gradually gave based. way to evidence and reason. First, there is a physical world independ- The gains were greatest and emerged earli- ent of human thought. Second, from birth, est in what are now referred to as developed every human acquires a body of knowledge countries, most particularly those of West- that represents the physical world they expe- ern Europe and North America but the phe- rience through their senses. This is their sub- nomenon has now spread world-wide. Today, jective knowledge. And, third, there is an most prosperous countries share a common independent body of knowledge that has feature. Although far from perfect, they have been developed through human thought developed or have adopted institutions in and communication. This includes the full areas of law, politics, health, education and range of shared ideas, such as stories, writ- social institutions (such as universities and a ings, art, music, mathematics and so on. As free press) that place great value on evidence far as I know, the first philosopher to bring and fact. These institutions are the foun- this together quite so succinctly was Karl dations of today’s civil society. In such an Popper (Popper 1972). It was not original environment, enquiry is rigorous and subject — Popper drew upon philosophical thinking to review by one’s peers. Key to this is our that has emerged over the last two millennia modern notion of knowledge: as the Oxford — but he did put it very clearly. He referred English Dictionary puts it, “the apprehen- to these as the Three Worlds and claimed sion of fact or truth with the mind; clear that they are three distinct ontological states. and certain perception of fact or truth; the Some philosophers would dispute this, but state or condition of knowing fact or truth”. it is a good way to think about things in the Why is this emphasis on truth so important? context of today’s discussion. Because it led to the settling of disputes with Truth evidence and reason, rather than by force, and this then became the foundation of In considering truth philosophers generally institutions that people could trust. look at two issues: what is meant by the words The topic of this forum — truth, rational- “is true” (referred to as the “truth predicate”); ity and post-truth — is important because of and the criteria for truth (for example, if I the threat to these institutions posed by the say the book is blue, how do I determine emergence of “post-truth”. What is meant by whether the book really is blue?). the term “post-truth”? Simply that objective An example might show why this distinc- facts are less influential in shaping political tion is important. Pontius Pilate was famously debate or public opinion than appeals to reported to have asked the question “what is truth?”. He should have asked “is he guilty?”. The point is that it is important not to mix 29 Journal & Proceedings of the Royal Society of New South Wales Hector — Rationality and Post-Truth up the question of what truth is with what The linguistic approach became influential we mean when we try to establish whether with the analytical philosophy of Russell and something is true or false. Wittgenstein in the early 20th century and The concept of truth only has relevance to was at its most influential with the logical self-conscious, linguistic beings, capable of positivists’ interpretation (in particular, the understanding and using concepts of truth semantic treatment by Tarski) of the cor- and falsity. Theoretical approaches to what is respondence theory of truth in the 1930s meant by “truth” fall into two broad groups. (Davidson 1990). There have been two Those that consider truth to be some genuine major epistemic approaches to truth, both property of a proposition, assertion or belief of which have their origins in Spinoza, Hegel — these are substantive approaches — and and other traditional philosophers. These are non-substantive approaches that argue that the pragmatist theory of truth, proposed by such a property or relation does not exist. C.S. Peirce, James, and Dewey in the late Non-substantive approaches argue that we 19th century (Haack 1976) and the coher- should not be misled by the similarity of the ence theory of truth, heavily influenced by truth predicate “is true” to other predicates the British idealist Bradley in the early 20th (such as, for example, “is blue”) into think- century (Schmitt 2004a). The coherence ing that similarly it denotes something real. theory of truth has been the more influential, In other words, it is wrong to interpret the particularly within the decision sciences. truth predicate as representing a genuine The correspondence and coherence theo- property (truth) of a thing, proposition, or ries of truth have been particularly influen- belief in the same way as blueness might be tial in the last century or so and these will considered to be a property. These deflation- be contrasted here. Both are substantive ary approaches (Lowe 1995, Schmitt 2004b) approaches in that both hold that truth propose that the truth predicate exists to exists and that it is a property of, or a rela- fulfil a purely linguistic function enabling tion involving a “truth-bearer” (that is, a speakers to do certain things, such as express proposition, sentence, or belief-state) and agreement with one another. a theoretical, omniscient “cogniser”. Cor- Another distinction that can be made respondence approaches propose that truth regarding theories of truth is between lin- is correspondence with “the way the world guistically- and epistemically-oriented is” and is independent from the cogniser, approaches. Modern, linguistically-oriented whereas coherence approaches argue that approaches attempt to analyse the meaning truth is coherence between truth-bearers of words and grammar to logically identify and include relationships between the and describe the nature of truth.