In his A Treatise Concerning the Principles of Human Knowledge (PHK), Berkeley proposes a purely mind-based universe in which only mental things—perceptions, volitions, and their cogitative substrates, i.e. minds—exist. He argues that our knowledge of Nature, what is conventionally believed to be “external reality”, is actually not based on the existence of mind-independent things. Instead, he claims that our understanding of Nature is formed by expectations of certain perceptions within very particular circumstances. In this essay, while I support his assertion that science is a system for predicting experiences, I contend that this claim is more consistent within a materialist conception of Nature in which mind-independent objects really do exist.
Minds as Distinct Centers of Observation
When an object is perceived by an observer, in what way does the observer really know the object? According to Berkeley, the object exists purely as it is presented to the observer; it has no other existence (PHK 4). Experiences consist only of what is received through the senses, which are framed into “ideas” within our minds. What really exists is our minds and the ideas that those minds actively perceive. As a strict empiricist, Berkeley does not deny experience itself—he just denies the existence of things that are held to exist apart from minds experiencing them. The mind holds distinct privilege in determining what is real; meaning, what exists unperceived by any mind cannot be held to exist at all (PHK 22, 58).
This seems to stand in direct contrast with traditional empiricism, at least in the realist sense it is commonly understood in today. When I see a table, there really is a table there, not the “idea” of one. When I close my eyes, it should still be there in front of me. A realist puts much value on sense-perception, assuming that what is presented to the senses is accurate and objectively real. Berkeley is not far from the mark, saying that while, yes, sense-perception is important, we should not go the extra step and assume there is something there that is independent of our perception. The perception of a table as table is simply a particular “framing” in our minds of a certain idea (PHK 22). In the absence of framing this idea, it is not just that we can still perceive a table and do not know what it is called—it does not exist for us at all [1].
Nature and Appearances
“Save the appearances” was a derisive term used by Plato to describe the convoluted theories of his day which added entire spheres to the cosmos in an effort to accurately predict celestial events, meanwhile disregarding the “true” nature of what they were modeling [2]. Spurning Platonic truth, however, Berkeley’s entire set of ideas can be boiled down to “save the appearances, because they are all we have.” Many scientists would curl their lips at the latter since they view themselves as investigating the structure of the universe behind appearances. After all, they may argue, there are many theories that defy common sense perceptions, but are unequivocally demonstrated to be true.
Berkeley has a stunning reply, however, when he discusses the motion of the Earth, which has no basis in human experience. Yet even he acknowledges that it stands “as a truth grounded on the clearest and most convincing reasons” (PHK 58). He initially says, “motion being only an idea, it follows that if it be not perceived, it exists not; but the motion of the earth is not perceived by sense” (PHK 58). So, what do astronomers mean when they say the Earth moves? “That if we were placed in such and such circumstances, and such or such a position and distance, both from the earth and sun, we should perceive the former to move among the choir of the planets…” (PHK 58).
We must realize that under the Berkeleyan view, Nature means something quite different from its commonsense definition as “the totality of objects within a mind-independent reality”. To a Berkeleyan empiricist, the idea of Nature can be better framed as “the space of all possible perceptions”. To have a science of Nature would therefore mean “to study under which strictly defined conditions it is possible to have strictly defined perceptions.” Therefore, when Newton formulated classical mechanics, it was not that he was defining a set of rules by which mind-independent planets should move. More modestly, he was defining a set of parameters by which astronomers could now observe the motion of planets if their telescopes were properly oriented towards the sky.
In other words, whenever we think we are advancing in our dealings with Nature, we are actually just dealing with our ideas of Nature, only at deeper levels. Investigating “behind the appearances” just means accepting an alternate, more elaborate set of appearances that one manipulates in an increasingly restricted manner. As our ideas of Nature get more and more refined, we gain a more nuanced picture of what kind of experiences to expect even when the conditions in which those experiences are observed become more complex. These more complex pictures, or models, are sets of ideas which serve to predict future sets of ideas. We can call these large models that contain sets of ideas theories. Theories change according to particular observations [3], and if there are new observations that lead to ideas that challenge systemic ideas of a given theory, the old theory is thrown out in favor of a new one.
Can We Salvage a Mind-Independent Reality?
There is at least one major implication that follows from the above Berkeleyan formulation of science as “experience-prediction.” It is that theories—ideas that help predict future successions of ideas—should usually have explanatory precedence over simpler ideas that result solely through sense-perception. For example, the simple fact that we do not observe viruses in our daily experience does not imply that they do not exist. It serves one well to operate at a more finely grained model of Nature (germ theory) and take proper precautions to prevent the experience of discomfort as a result of sickness. Such a fine-grained model of Nature may not be necessary all the time, however, since successfully incorporating the motion of the Earth into one’s personal model of Nature may lead to undesired experiences of vertigo. Sometimes it is just better to go with a coarse-grained model.
I think it is possible to have a Berkeleyan anti-realist attitude towards science without being an idealist, and the following section shall serve as my argument. We can compare two broadly conceived theories: “Mind as Nature” versus “Mind as a part of Nature”. The first is the idealist model; the latter is the materialistic model. The first model assumes, following Berkeley, that the mind is primary—what exists depends on a mind perceiving it. “Mind as a part of Nature” holds that the mind is one of many features of Nature, and should itself (as the brain) be considered a mind-independent object, so to speak. Finally, I posit that the idealist model should be taken as the coarse-grained description of minds and their perceptions that should be supplanted by the more fine-grained description of materialism.
The chief weakness of the idealist model is that it cannot address the act of perception itself, assuming it to be fixed across all circumstances. What “experiences can be expected within particular circumstances” only holds if that act of perception-making remains constant, since otherwise, the same object can be experienced in quite different ways depending on the variability of perceptions. Idealism is based on the supposition that perceptions at a given moment can be fully trusted to give us good enough ideas that can help us predict future experiences, all of which entails that we do not need a theory for perception itself. “Mind as Nature” works if one wants to make models of Nature based purely on sense-experience, but it does not allow you to make the most comprehensive theories about sense experience.
In fact, neuroscientific (i.e. materialist) theories do possess models of the mind based on observations about the brain, thereby encouraging us to treat the mind as “part of Nature”. This is because the materialist model instead considers that although we may think that our sense-perception is the final arbiter of knowledge, we achieve a more finely grained model of minds by assuming that our minds, because they are instantiated in a brain, are themselves part of a mind-independent reality. Imagine opening one’s own skull and attempting neurosurgery on oneself. Zap the occipital lobe, and you get drastic changes in visual perception. Cut through the amygdala, and become the only person in the theater who doesn’t feel an ounce of fear during jump scares. It becomes immediately clear that this strange, squishy organ, out of all “external” objects, seems to have the most causative power over our sense-experience. So, the only sensible conclusion is that the very object that appears before your senses is the very tool which you are using to look at it! Instead of thinking that this object in appearance has no existence apart from personal observation, is it not more coherent to believe it exists as a mind-independent object that always causes one’s perceptions, even when one’s skull is closed? Such a materialist model can predict future sense experiences (and ideas) more comprehensively than the more coarse-grained model it replaces. The only requirement is that we appeal to a brain, a kind of mind-independent object, in which sense-experience is based.
A Berkeleyan could object here and refer to God, a critical aspect of Berkeley’s philosophy I have not yet discussed. Berkeley’s God is the omniscient Mind who has ideas of all things, even planetary motion we are ignorant of, and so keeps everything in existence by continually perceiving them (Dialogues 212). I grant that while God perceiving the motion of planets could allow for their existence independent of our knowledge, I do not think the same holds true for human brains. For God to have ideas of neural events happening unbeknownst to the mind to which they belong implies that God is responsible for maintaining not only the objects that an individual perceives but also for their very perceptual abilities! This is an extremely tenuous claim that I see no reason to accept, seeing how this explanation falls into a variety of occasionalism[1] if taken to its logical end. Besides, for God to have continued perceptions of individual mental states entails that his ideas must be as subject to change as those of temporal beings, a conclusion Berkeley should find quite disagreeable (considering certain classical theological beliefs of the Church, like God’s immutability).
This is all to show that of the two models, “mind as part of Nature” is superior to “mind as Nature”, since if we hold the latter, it seems like the process by which we make perceptions is completely disregarded. Much historical scientific progress occurred not only because we have found even more elaborate conditional statements describing expected perceptions, but also because we developed new tools with which to perceive. And finally, while we may always be ignorant as to the true nature of what we are ultimately perceiving (in the anti-realist sense), we should nevertheless believe it is out there.
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Notes and References
[1] Cf. descriptions of patients with visual agnosia, as noted in Oliver Sacks’ book The Man Who Mistook his Wife for a Hat. Sacks describes individuals that can see clearly yet cannot identify or recognize everyday objects.
[2] Coming of Age in the Milky Way, Ferris
[3] Observations are noted perceptions. Perceptions are broad, as anything which is sensed could be called a perception. For my purposes, observations are understood as acts of the mind that filter out only relevant perceptions.
[4] The idea that God continually intervenes to unify mental and bodily events. I disagree with this for the simple reason that I don’t blame God for the pain I feel when I stub my toe (however tempting this may be).
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Amanuel Sahilu