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| Thomas Nagel wondered if the world a bat perceives is fundamentally different to our own |
By Keith Tidman
Do we experience the world as it objectively is, or only as an approximation shaped by the effects of information passing through our mind’s interpretative sieve? Does our individual reality align with anyone else’s, or is it exclusively ours, dwelling like a single point amid other people’s experienced realities?
We are swayed by our senses, whether through the direct sensory observation of the world around us, or indirectly as we use apparatuses to observe, record, measure, and decipher. Either way, our minds filter the information absorbed, becoming the experiences funneled and fashioned into a reality which in turn is affected by sundry factors. These influences include our life experiences and interpretations, our mental models of the world, how we sort and assimilate ideas, our unconscious predilections, our imaginings and intuitions unsubscribed to particular facts, and our expectations of outcomes drawn from encounters with the world.
We believe that what serves as the lifeline in this modeling of personal reality is the presence of agency and ‘free will’. The tendency is to regard free will as orthodoxy. We assume we can freely reconsider and alter that reality, to account for new experiences and information that we mold through reason. To a point, that’s right; but to one degree or another we grapple with biases, some of which are hard-wired or at least deeply entrenched, that predispose us to particular choices and behaviours. So, how freely we can actually surmount those preconceptions and predispositions is problematic, in turn bearing on the limits of how we perceive the world.
The situation is complicated further by the vigorous debate over free will versus how much of what happens does so deterministically, where life’s course is set by forces beyond our control. Altering the models of reality to which we clutch is hard; resistance to change is tempting. We shun hints of doubt in upholding our individual (subjective) representations of reality. The obscurity and inaccessibility of any single, universally accepted objective world exacerbates the circumstances. We realise, though, that subjective reality is not an illusion to be casually dismissed to our suiting, but is lastingly tangible.
In 1974, the American philosopher Thomas Nagel developed a classic metaphor to address these issues of conscious experience. He proposed that some knowledge is limited to what we acquire through our subjective experiences, differentiating those from underlying objective facts. To show how, Nagel turned to bats’ conscious use of echoed sounds as the equivalent of our vision in perceiving its surroundings for navigation. He argued that although we might be able to imagine some aspects of what it’s like to be a bat, like hanging upside down or flying, we cannot truly know what a bat experiences as physical reality. The bat’s experiences are its alone, and for the same reasons of filtering and interpretation, are likewise distinguishable from objective reality.
Sensory experience, however, does more than just filter objective reality. The very act of human observation (in particular, measurement) can also create reality. What do I mean? Repeated studies have shown that a potential object remains in what’s called ‘superposition’, or a state of suspension. What stays in superposition is an abstract mathematical description, called a ‘wavefunction’, of all the possible ways an object can become real. There is no distinction between the wave function and the physical things.
While in superposition, the object can be in any number of places until measurement causes the wavefunction to ‘collapse’, resulting in the object being in a single location. Observation thus has implications for the nature of reality and the role of consciousness in bringing that about. According to quantum physicist John Wheeler, ‘No ... property is a property until it is observed’, a notion presaged by the philosopher George Berkeley three centuries earlier by declaring ‘Esse est percepi’ – to be, is to be perceived.
Evidence, furthermore, that experienced reality results from a subjective filtering of objective reality comes from how our minds react to externalities. For example, two friends are out for a stroll and look up at the summer sky. Do their individual perceptions of the sky’s ‘blueness’ precisely match each other’s or anyone else’s, or do they experience blueness differently? If those companions then wade into a lake, do their perceptions of ‘chilliness’ exactly match? How about their experiences of ‘roughness’ upon rubbing their hand on the craggy bark of a tree? These are interpretations of objective reality by the senses and the mind.
Despite the physiology of the friends’ brains and physical senses being alike, their filtered experiences nonetheless differ in both small and big ways. All this, even though the objective physical attributes of the sky, the lake, and the tree bark, independent of the mind, are the same for both companions. (Such as in the case of the wavelength of visible light that accounted for the blueness being interpretatively, subjectively perceived by the senses and mind.) Notwithstanding the deceptive simplicity of these examples, they are telling of how our minds are attuned to processing sensory input, thereby creating subjective realities that might resemble yet not match other people’s, and importantly don’t directly merge with underlying objective reality.
In this paradigm of experience, there are untold parsed and sieved realities: our own and everyone else’s. That’s not to say objective reality, independent of our mental parsing, is myth. It exists, at least as backdrop. That is, both objective and subjective reality are credible in their respective ways, as sides of the whole. It’s just that our minds’ unavoidable filtering leads to the altering of objective reality. Objective reality thus stays out of reach. The result is our being left with the personal reality our minds are capable of, a reality nonetheless easily but mistakenly conflated with objective reality.
That’s why our models of the underlying objective reality remain approximations, in states of flux. Because when it comes to understanding the holy grail of objective reality, our search is inspired by the belief that close is never close enough. We want more. Humankind’s curiosity strives to inch closer and closer to objective reality, however unending that tireless pursuit will likely prove.
