In his Principles of Human Knowledge and Three Dialogues, Bishop Berkely famously argued that matter did not exist. Only ideas in the mind. Idealism was born. What was he arguing against? He was primarily arguing against the representationalist dualism of Descartes and Locke, that claimed that the mind consists of representations of the external world. He thought that such a representationalist paradigm leads to skepticism because it is possible that our representations don’t correspond to any reality. Berkeley had several arguments against this representationalist philosophy, but what is more interesting is his argument against those who deny the premises of representationalism. To this, Berkeley offered what is sometimes called the “master argument”:
… I am content to put the whole upon this issue; if you can but conceive it possible for one extended moveable substance, or in general, for any one idea or any thing like an idea, to exist otherwise than in a mind perceiving it, I shall readily give up the cause…. But say you, surely there is nothing easier than to imagine trees, for instance, in a park, or books existing in a closet, and no body by to perceive them. I answer, you may so, there is no difficulty in it: but what is all this, I beseech you, more than framing in your mind certain ideas which you call books and trees, and at the same time omitting to frame the idea of any one that may perceive them? But do not you your self perceive or think of them all the while? This therefore is nothing to the purpose: it only shows you have the power of imagining or forming ideas in your mind; but it doth not shew that you can conceive it possible, the objects of your thought may exist without the mind: to make out this, it is necessary that you conceive them existing unconceived or unthought of, which is a manifest repugnancy. When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas. But the mind taking no notice of itself, is deluded to think it can and doth conceive bodies existing unthought of or without the mind; though at the same time they are apprehended by or exist in it self.
So, while this argument was designed to work if you are a direct realist, what happens when you deny the framework of direct/indirect realism? I can’t help but view this argument through a Heideggarian lens and wonder what Philonous would say to someone who denied the subject/object distinction and thus the perceiving ego altogether. I think Heidegger would have denied the premises upon which Berkeley’s argument stood. If you deny that humans have subjective minds that perceive the world, then it doesn’t matter whether the “world” perceived is immaterial or not. Heidegger would still go with the parsimonious, scientific materialism but what matters is that the world of humans is imbued with significance through the pragmatic interactions of everyday life. The subjective mental realm that Berkeley works with is primarily a metaphorical holdover from the popular philosophy of the times. Berkeley couldn’t help but frame his philosophy in terms of a mental subject interacting with the world, either material or immaterial. However, thanks to 20th century thinkers like Heidegger giving us a new vocabulary to work with, the philosophical problems of the 17th century seem antiquated in the same way that ptolemaic astronomy is outdated to modern astronomers.
So, it isn’t that Berekey’s argument are wrong per se, it is just that the philosophical framework that they rest upon has been cast aside in favor of new metaphors and vocabularies.