The Value and Limits of Reason

In this post I will share the notes I made when hearing Iain McGilchrist speak about the value and limits of reason on 4-day Field & Field course I recently attended in the Cotswolds, UK. For a background to the content of this post, see my previous two posts relating to this course and the page on this blog devoted to The Divided Brain and Iain McGilchrist’s work.

Iain McGilchrist described this talk as ‘a series of soundbites’ and I expect this is how these notes will come across. My note-taking can be lacking in both accuracy and coherence, and as such, I stress that these notes are mine. They are a record of what I heard, what I noted as significant for me (and by no means everything that Iain said), and necessarily reflect how I interpreted what I heard. I want to stress that any errors are very definitely mine. Please feel free to challenge or correct me in the comments.

A bit of background

Iain has written about reason before. There is a section in The Master and His Emissary devoted to a discussion of ‘Reason Versus Rationality’ (p.64), where Iain argues that there are different kinds of reasoning and that although linear, sequential argument is better executed by the left hemisphere, the right hemisphere is better at deduction and less explicit reasoning (p.65).

Rationality involves a causative linear way of thinking in a limited environment. Reason seeks a global, holistic understanding which only makes sense in the round.

This discussion about reason and rationality in Iain’s book invited a response from author Kenan Malik, who in 2013, wrote an article critical of Iain’s arguments – to which Iain wrote a robust response. This discussion/debate was not referred to on the Field & Field course, but it is probably worth reiterating before sharing my notes that at the beginning of The Master and His Emissary, Iain makes it clear that he is not demonising reason.

I hope, however, it will be obvious from what I say that I hold absolutely no brief for those who wish to abandon reason or traduce language. The exact opposite is the case. Both are seriously under threat in our age, though I believe from diametrically opposed factions. (The Master and His Emissary, p.6)

Equally this book has nothing to offer those who would undermine reason, which, along with imagination, is the most precious thing we owe to the working together of the two hemispheres. My quarrel is only with an excessive and misplaced rationalism which has never been subjected to the judgment of reason, and is in conflict with it. (The Master and His Emissary, p.7)

And a quote from Blaise Pascal

There are two equally dangerous extremes – to shut reason out, and not to let nothing in. 

The Value of Reason (NB these are my notes, based on my hearing, and my interpretation)

As Whitehead and Russell pointed out it is important to think logically. A widespread problem is that science fails to question its methods, so reason keeps us from complacency, but reason should also question its own methods.

Reason is a consistency tool, but it has to start from something. It starts from axioms (axiom comes from the Greek word axia, meaning values). Reason can’t make people see what you can see; it can only lead them closer.

As David Hume famously wrote in his A Treatise of Human Nature (p.415),  “Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.” So reason is a tool which we should control. It is our servant, but not our master. McGilchrist writes on p. 203 of The Master and His Emissary:

He [Hume] did not mean that unbridled passion should rule our judgments, but that the rational workings of the left hemisphere (though he could not have known that that was what they were) should be subject to the intuitive wisdom of the right hemisphere (though he equally could not have recognised it as such).

Dan Sperber and Hugo Mercier have a different take on the value of reason, which they propose in their ‘argumentative theory’ is not principally to improve knowledge and make better decisions, but rather to win arguments. They believe that we do not seek truth, but rather arguments that support our views; we are, after all, competitive animals. For a more in depth discussion of this, see, for example, this post ‘Is reasoning built for winning arguments, rather than finding truth?

Some Problems with Reason (NB these are my notes, based on my hearing, and my interpretation)

G K Chesterton is quoted as saying: “A madman is not someone who has lost his reason but someone who has lost everything but his reason”. Make of that what you will. My interpretation is that reason alone is not helpful. The full quote might help:

“If you argue with a madman, it is extremely probable that you will get the worst of it; for in many ways his mind moves all the quicker for not being delayed by things that go with good judgment. He is not hampered by a sense of humour or by clarity, or by the dumb certainties of experience. He is the more logical for losing certain sane affections. Indeed, the common phrase for insanity is in this respect a misleading one. The madman is not the man who has lost his reason. The madman is the man who has lost everything except his reason.”

In this section of his talk, Iain alerted us to some of the potential limits of reason.

  • Reason prioritises the system over reference to reality, which can lead to a false premise, e.g. as in the porcupine is a monkey syllogism (see p. 192 in The Master and His Emissary for further discussion of this).
      1. Major premise: all monkeys climb trees;
      2. Minor premise: the porcupine is a monkey;
      3. Implied conclusion: the porcupine climbs trees.
  • We judge many things on the basis of experience rather than reason, e.g. love. There are an infinity of such experiences that surpass reason.

Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones.

  • There are an infinite number of truths that we can’t get to with reason (I recently wrote a post that included reference to Julian Baggini’s book – A Short History of Truth, and I have heard Iain talk about truth before). Some things do come with linearity, e.g. rational people formulate goals and take the most direct route to achieving these goals, but some things can’t be pursued or willed. Happiness, for example, is a by-product that comes from forgetting yourself; it can’t be pursued. Sleep and appetite can’t be willed. Wisdom, humility, courage, love, faith, admiration, sympathy (and more) similarly can’t be linearly pursued. Understanding cannot be given, imposed or transmitted.
  • Similarly, morals cannot be derived from reason alone. Moral values are not something we can work out rationally. They are not utilitarian. They come from within (see the work of David Hume and p.86 of The Master and His Emissary). Morals are irreducible aspects of the phenomenal world.
  • Reason involves distancing ourselves from the natural world, but taking things out of context (abstraction) can be a mistake. John Dewey warned against the neglect of context. “I should venture to assert that the most pervasive fallacy of philosophic thinking goes back to neglect of context”  (see The Philosophical Fallacy – and p.144 The Mater and His Emissary). Things change as context changes. The response to this is often to categorise things on the basis of a single feature, but we need overlapping contexts. It is the left hemisphere that categorises things on the basis of a single feature. The right hemisphere looks for general similarity. For the left hemisphere there is a need to focus attention narrowly and be precise, but serendipity plays a big part in determining what can be predicted, and the more precise and reduced something is, e.g. language, the less useful it is. Being too precise means losing the overall picture, just as a map has precision, but this does not reflect life and all that we cannot quantify, such as beauty, anger, hunger. Some values cannot be measured and being precise can be less helpful than being imprecise, and even entirely irrelevant.

As Edmund Burke said: ‘It is the nature of all greatness not to be exact’ and ‘A clear idea is another name for a little idea’. Similarly from Rabindranath Tagore:

  • Finally, there is always a truth in the opposite of something. The left and right hemispheres both contribute to logic, but the right hemisphere makes a better contribution to deduction and the left hemisphere to induction. The right hemisphere is better at testing reality, but the left hemisphere gets swayed by what it already knows.

Iain ended this talk with reference to The Monty Hall Paradox to illustrate the point that the correct choice in this game is so counterintuitive it can seem absurd, but is nevertheless demonstrably true. The Prisoner’s Dilemma presents a similar paradox (see p.145 The Master and His Emissary). I took this to mean that adopting a right hemisphere perspective on the world and recognising that reason can have both value and limitations can seem counterintuitive.


McGilchrist, I. (2009). The Master and His Emissary. The Divided Brain and the Making of the Western World. Yale University Press.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s