What’s the point in being rational?

02/06/2025

What work does the concept of rationality do? What does it mean to say someone is or is being rational or irrational? In this blog post Dr Andrew Kirton questions what attributions of rationality might amount to and in what way, if any, they are useful.

When I see philosophers talk of rationality, I feel like some square block is trying to fit into a round hole in my brain, or like I missed school yesterday and now I’m having to pretend to understand what today’s lesson is about. So I’ve tried to decode what they’re talking about when they’re judging agents, attitudes and actions as (ir)rational.

One time, after opening up about my confusion, a co-author friend suggested that if we’re not appealing to rationality in exploring matters of agency, then we’re just doing psychology badly: we’re not contributing anything distinctive of philosophy, in the form of frameworks or answers that tell us what is optimal for us to think, want, or do. So calling some action, agent or attitude A (ir)rational means we’re appealing to some framework or external standard that we can judge A as meeting or falling short of. That standard might also allow us to unpack how the mind, action, agency, maybe morality too, fit together. By talking about the rationality of belief, we get a sense of the function or nature of belief, through seeing how it works in an intelligible goal-driven agent.

My difficulty with rationality is that I think it doesn’t really pick out an actual external standard. When we’re offering judgements of particular agents, attitudes or actions being rational or not, we’re really offering a kind of objective-sounding substitute for saying ‘that makes / doesn’t make sense to me’. If that’s what a judgement about rationality offers, it is always drawing on our background understanding of how agents or attitudes like A generally operate, so whether A squares up against that prior framework, having projected it onto the case in question.

Saying A is irrational carries some imperative force: that A ought to be brought in line or corrected (and A being labelled rational is like a thumbs up ‘yep, makes sense’). Does this imperative force of ‘that’s / you’re irrational’ ever prove effective in changing a mind? I don’t really care about being deemed rational by someone else; maybe even by myself. I just want to make choices that are good for me. What’s the rationality stamp of approval doing, beyond just pointing out the reasons to others why some other thing is more sensible?

Suppose we tell our friend their decision to leave their job is irrational. This is suggesting that leaving their job doesn’t make sense, that it’s self-defeating or incoherent. What should our friend do with this? ‘Irrational’ carries a sense of judgement and condescension, so they might tell us to, frankly, ‘do one’. It doesn’t smack of curiosity about their experience and choices. We’re suggesting they’re failing to mentally cohere. It’s presumptuous that we know everything about what matters to them and all the relevant facts. Calling them irrational will probably just incline them to double down.

Perhaps a minimal role for a judgement of irrationality is to serve as a prompt for more reflection on what the evidence is, or what matters to us. Like Louis Theroux raising his eyebrows at us. But again, this is just a call to reflect on what’s sensible or best. As any good therapist will say, what’s best for us to do can only be decided and executed by ourselves, rather than via someone suggesting that we’re mentally or practically incoherent. As we work out what’s going on with ourselves, we might realise there are unconscious needs behind our actions that only we can figure out, possibly with the help of a friend, therapist, or empirical research.

Which leads to the idea that irrationality gestures toward the realm of unconscious impulses or animal drives that operate on a rough-and-tumble biology grounded logic of their own, bubbling up and derailing our conscious efforts to direct our actions, thoughts and feelings in ways we decide are better for us. An action being irrational means something lower down is derailing us from our goal. Yet there is nothing mentally incoherent or not-making-sense about that lower down processing and the likelihood of derailments, as they’re a consequence of how we work. Our goal should be to figure out how to minimise derailments, and a simple judgement of irrationality doesn’t shed any light on how to better do that. Bringing it back to my co-author friend’s point: it seems to me if the point of philosophy is giving frameworks for what’s optimal to think or do, then we’ll just do it badly unless we also look at psychology.

Dr Andrew Kirton has written about the nature of trust and its role in interpersonal relationships, institutions and societies. He did his PhD at the University of Manchester and has worked in IDEA The Ethics Centre at the University of Leeds’ School of Philosophy, Religion and History of Science since 2018. His teaching specialism is AI Ethics. His research specialisms are in moral philosophy and the philosophy of mind and action. He is currently trying to work out various ideas surrounding the way we settle on viewpoints through dealing with cognitive dissonance and our needs for attachment and social acceptance, and how morality falls out of this.