“How prone to doubt, how cautious are the wise!”  

Homer, some 3.000 years ago

How reliable is our common sense? It gets us by on a day-to-day basis mostly without big blunders. So we can agree that common sense is reliable as an adaptability tool. Thanks to this capacity of our common sense we are flexible enough to adapt to a great variety of environments and circumstances. This is big and we would be fools to underestimate such a ‘tool’. Yet, if this tool is good for adapting, is it also good for truth-finding? Is there a link between being good at adapting and being good at discovering truths? In other words, can we rely on our common sense to help us form true (and not just adaptive) beliefs?

Alvin Plantinga is convinced that there is a deep conflict between science (truth-seeking enterprise) and a general worldview sometimes referred to as metaphysical naturalism (physical reductionism position – all reality can be explained through the physical processes). Although it might seem surprising and, indeed, counter-intuitive that there should be a conflict between science and naturalism, that is exactly what Plantinga argues. For him, metaphysical naturalism is a self-defeating position to hold, if at the same time you accept evolutionary theory as a valid account of the development of life on Earth and consider your cognitive faculties reliable in enabling you to form true beliefs. Why does Plantinga think that?

Basically, his main proposition is that the likelihood of our cognitive faculties being reliable in forming more true beliefs than false ones is very low in case we accept naturalism and evolutionary account of our development. That’s because, on this naturalistic (physical reductionist) reading of evolution, there is no need for our cognitive faculties to be forming true beliefs. What is important, what really counts in such a naturalistic picture is that whatever beliefs we have (as formed by our cognitive faculties) these beliefs should increase our adaptability and, therefore, chances of survival. Or, perhaps at the very least, these beliefs should not impede our adaptability. Our beliefs can be true or false, but they must be adaptive. There is no link between being adaptive and being true. On this naturalistic account then, truth is an irrelevant byproduct from the perspective of natural selection. A bleak picture. 

If we indeed hold the physical reductionism position as our prevailing view of reality, then, given what has been described – so Plantinga argues – we have no warranted reason to rely on our cognitive faculties being good at forming true beliefs (about anything!). And the next logical step takes us right to the edge of the abyss: if I cannot be confident that my belief-forming faculties supply me with generally true beliefs, then I cannot be confident about the truth of any belief I hold, including my belief in physical reductionism being true or my own belief-forming faculties being capable of generating true beliefs. It is a vicious circle of inescapable and drastic scepticism, a self-defeating position. A place that, as Plantinga observes, nobody could reasonably want to be at. 

Have you noticed how a silent actor has appeared on the stage and is noiselessly steering the show? Enter our ubiquitous reliance on common sense. That self-defeating position, that vicious circle that Plantinga presents, feels like teetering on the edge of the abyss precisely because it contradicts one of our deeply held convictions – that we can rely on our common sense to form generally true beliefs about reality. Plantinga thinks we are justified in holding this conviction, this fundamental assumption of ours. He is not alone. I have written a review of American philosopher’s Thomas Nagel’s 2012 book “Mind and Cosmos” where he upholds similar high regard for human common sense and considers that, for instance, even the most extravagant scientific theories should be compatible with our common-sense beliefs. But should they? 

It is relatively recently (in the 70s and 80s of the 20th century) that the psychologist and economist Daniel Kahneman and his colleagues posed a very well-researched and evidence-supported challenge to the prevailing assumption that humans are rational decision-makers (thus laying foundations for the field of behavioural economics, among other things). In his 2011 book “Thinking, Fast and Slow”, Kahneman summarizes his research and brings the omnipresence of our cognitive biases and mental ‘shortcuts’ to the public’s attention. It is not without reason that the book that suggests that people have too much confidence in human judgement became a best-seller worldwide. Yet, despite the impressive evidence of the shortcomings of our cognitive capacities to reliably form true beliefs, confidence in just that kind of reliability remains widespread. 

Might this conviction itself represent one of our cognitive biases, perhaps contributing to our adaptability but obstructing our access to truth? After all, it is largely because of this tendency to be over-confident in the truth of our beliefs that the scientific, truth-seeking enterprise has so many checks and balances built into it. If a scientific hypothesis wants to become an accepted scientific theory, it must successfully withstand the scrutiny with which it will be rigorously challenged. And even then any good scientist will concede that all scientific knowledge is always tentative – until the next, better, more truth-capturing theory comes along.

So then, are we jumping to conclusions when thinking about our common sense and truth-finding? Could we be making too big of a leap when we correlate the reliability of our common sense in forming adaptive and, no doubt, sometimes true beliefs with its reliability in forming generally true ones? Are the thinkers mentioned here (and many of us) justified in holding our common sense as a reliable tool for discovering the truth? Must something necessarily be true or false just because we feel like it should, just because it would make sense to us? Is there perhaps something deeper to the whole story? Might our confidence reflect our over-self-identification with our reliable cognitive abilities? A lot to think about, no doubt. What does your common sense tell you? 

keep exploring!

^*Image source: By Brianlocicero – Transferred from en.wikipedia to Commons by AndreasPraefcke using CommonsHelper., Public Domain, https://commons.wikimedia.org/w/index.php?curid=5153369