In philosophy, idealism argues that reality is a mental construct, or that ideas are the highest form of reality. Ancient Indian Vedanta philosophy taught that an all-pervading consciousness is the true nature of reality. Plato said that ideas were the absolute, unchanging, highest form of reality. Immanuel Kant argued that our knowledge of reality is completely based on our own, mental structures.

Reality can be measured

Critics of idealism poured cold water on it by saying that the physical constants of nature are consistent and remain unchanged, regardless of what’s going on in a person’s mind. Analytic philosophers such as Bertrand Russell, cited the physical constants as rigorous proof that reality was real, independent of the observer: the speed of light, the gravitational constant, the elementary charge and measurement standards for example. All of science is built on the reliability of these properties and so we know for certain that external reality is real, because they remain the same regardless of who is measuring them in whatever place. Getting hit on the head by a brick is going to hurt, regardless of your ideal mental structure. Rocks are hard, water is wet, light is bright, fire is hot and ice is cold – we take these things for granted and they are certain and unquestionable facts. 

Reality cannot be separated from observation

In the early 20th century, it seemed like the debate was settled, but then Einstein showed that, while the speed of light is indeed constant, the position and speed of the observer alters our perception of it. Gravity too, alters according to where you are and the mass of objects near to you. Time isn’t fixed either, and it also seems to alter under certain circumstances. Even right down to the tiniest quantum particles, observation plays a critical role in determining the behaviour of things we know as reality. Relativity and quantum mechanics challenge the notion of objective reality, and indicate that reality cannot be separated from the act of observing it. This puts the ball back in idealism’s court because science rejects the possibility of knowing the existence of any thing independent of observation.

Reality is real but personal

This is not to say that reality isn’t real. If the laws of thermodynamics weren’t reliable, we’d all be in for a few problems the next time we tried to cook dinner. We live in an isotropic bubble called Earth and within it, light, gravity, mass and time are pretty stable so we don’t usually encounter the mind-bending phenomena of relativity, nor is quantum woo-woo much of an issue in our day to day lives. 

And yet, the observer effect cannot be dismissed out of hand. What it implies is that, however real some things appear to be, they are all subject to individual perspective and the conditions under which we experience them. This is the paradox of reality: however robust it can be externally verified, it is always subject to interpretations of the human mind. For example, we can know and measure the speed of light as a constant, but what its implications are and what we do with that knowledge, is subject to human interpretation. Galileo is first credited as trying to measure the speed of light, but it wasn’t until fairly recently that the speed of light was used in fibre optic communications. Discovering scientific constants, and employing them usefully, is a product of the mind. Even when knowledge is stored in external data systems, it is fairly redundant until it is transferred into a human mind and acted upon. 

On a day to day basis, our notions of reality are constructed from our own unique perspective. The external world is there, but it can only ever be experienced through singular minds that fabricate it using the senses, which are themselves limited and prone to biases. The reality I experience, might not be the reality you experience.

Are ideas the highest form of reality?

Idealists such as Kant knew this. His transcendental idealism says we can only experience reality as mental constructs, not independent things in themselves. In this way, he said, we mould and shape our own interpretation of the world through our senses. 

What is also true is that all of human endeavour, and the greatest ideas ever conceived on the Earth, began or live, in the mind. All knowledge is based on mental constructs: skyscrapers, bridges, space ships, cathedrals, medicine, astronomy, they only exist in the minds of those capable of understanding them and they can certainly only ever be designed and constructed by such. Plato was right in this sense, ideas are the highest form of reality because ideas actually shape the highest forms of reality as we know it. 

A radical view

The remaining question is, how far do you want to take this? Some, more radical forms of idealism propose that all of reality is in some way mentally constructed, immaterial or non-physical, or that it is an aspect of a spiritual absolute. In fact, pure Idealism asserts that consciousness is the origin and prerequisite of all phenomena. This is where things get complicated, as Idealism separates into a myriad of different belief systems and religious viewpoints, many of which are quite different and even opposing. 

More spiritual people believe we each possess a higher level of consciousness that links to a universal consciousness, and I can see something in that. Certainly, swamis and gurus have attuned their minds to be in states of realisation that few others possess. They tell us an all-pervading consciousness is the true nature of reality, that an infinite, immortal self lies beyond the intellect, mind, and ego, and who am I to disagree? It’s tempting to want evidence of the validity of these claims, but to do that misses the point entirely. These ideal states aren’t scientific or centred in any form of physical reality we know of, so why would we think science can give us an answer to them? 

Reality in a nutshell

What idealism suggests is that there isn’t only one world – there are 8.3 billion of them, and that’s only if you count the human perspectives. Each of us constructs our own world, makes our own truth, and builds our own reality. You are inventing your own world as you go, constructing your own meaning, even in the face of an externally verified reality.

You can stop there and not dwell on it any further, or you can try to unravel what the implications are of having a mind that can conceptualise higher order things. Is it just an evolutionary fluke, a coincidence ? Or is the gateway to a transcendental, immortal self? Quite literally, that version of reality is yours, and yours alone to make, regardless of what is physically real.

Sources: Idealism Wikipedia, Does our physical reality exist in an objective manner? Ethan Siegel, Big Think, Transcendental Idealism, Immanuel Kant, The concept of soul or self in Vedanta, written By Swami Tathagatananda