Sunday, November 21

Mind theory - seeing ourselves part 2

This discussion paper continues the two eminent scholar’s different perspectives on modern mind theory.  

To reiterate, Raymond Tallis explores our uniqueness as a part and apart from nature whilst Rodolfo R. Llinas favours an evolutionary explanation- where mind is purely a product of the brain.

 

Beginning with Llinas, he links consciousness to our neuronal circuitry- to talk one through the predictive power of neurons. His theory links the principles of computer game theory and the stock market as analogous to our high powered efficient brain functionality. For instance a stock market's ability from a huge input of individual buyers and sellers to subsequently flicker emergent buy and sell prices. In other words, our predictive neuronal circuitry power is analogous to the simultaneous operations of multi powerful computers, inclusive of some kind of clock or timing device to explain motor control.

 

At this point his theory lacks any specificity as to how this predictive circuity concisely communicates our feelings about everyday experiences which he covers in the following chapters. Therein he introduces the idea of Qualia which he links to an evolutionary advantage in higher order thinking that arose in tandem with the central nervous system to which it relates.           

 

Although his ensuing commentary is very interesting and well researched-  in relation to nerve cells, their personalities, the evolution of the eye, emotions and memories, it is not until one reaches the section on Qualia, that, from my perspective one can clearly deduce how this all hangs together in terms of our consciousness.

 

Qualia  

Llinas begins his commentary on the assumption the reader is already familiar with the term, so, by way of a brief introduction here is my summary : Qualia first arose way back in 1929 to support C.S. Lewis’s explanation of sense data theory, but has since been expanded in modernity. It might be defined as any phenomenal properties of experiences that have Qualia- ones in which we have phenomenal consciousness. By phenomenal consciousness we mean one is aware of that thing or of feelings or emotions in the mind's representations - being necessarily mental states.    

 

There is some disagreement as to what to include as  Qualia but the broad consensus is to accept sounds, feelings, sensations, visualisations and so forth.

 

Michael Tye states he would certainly include (1) Perceptual experiences, for example, experiences of the sort involved in seeing green, hearing loud trumpets, tasting liquorice, smelling the sea air, handling a piece of fur. (2) Bodily sensations, for example, feeling a twinge of pain, feeling an itch, feeling hungry, having a stomach ache, feeling hot, and feeling dizzy. Think here also of experiences such as those present running flat-out. (3) Felt reactions or passions or emotions, for example, feeling delight, lust, fear, love, feeling grief, jealousy, regret. (4) Feel moods, for example, feeling elated, depressed, calm, bored, tense, miserable.

(For more here, see Haugeland 1985, pp. 230–235) Stanford Encyclopaedia of Philosophy - Tye, Michael, "Qualia", Fall 2021.

 

But Llinas simply defines Qualia as any subjective experience that is generated via the central nervous system. Qualia becomes integral to his theory of our enhanced evolutionary journey: that functional architecture of the brain as a product of the slow tumbling of evolution where  natural selection has found it to be the most beneficial in terms of species survivability. My argument is that the sensory experience leading to active movement (motricity through the function of prediction is the ultimate reason for the very existence of the central nervous system. Page 202 -Qualia from a Neuronal Point of View/ I of the Vortex. 

 

Thus for Llanas his evolutionary reason for the existence of qualia is straightforward – they represent the sensations as geometric, electrically triggered events. He believes the patterned activity in neurons and their molecular counterparts are sensations. Page 210- Qualia from a Neuronal Point of View/ I of the Vortex.  

 

Hence our consciousness represented by enhanced awareness was facilitated by Qualia extending throughout the central nervous system. That favoured approach in evolution was underwritten by the principle smarter gave the favoured survival prospect.  

 

According to Llinas we fall out of consciousness such as when we are asleep, when Qualia is no longer active, as is also the case during epileptic seizures.

 

But my particular interest is the answer he gives to the question ‘The Hard Problem”: Is it True Science Will Never Understand Feelings? Page 210- Qualia from a Neuronal Point of View/I of the Vortex  

 

He confirms we will have to find out more about intricate workings of the nervous system before this is possible. But he does provide further commentary from mind philosopher David Chalmers and concludes on the necessity for Qualia. His so-called ultimate bottom line is that Qualia is that part of the self that relates (back) to us! 

 

Turning now to Raymond Tallis he doesn’t place the same emphasis on Qualia.  Rather (page 95 seeing ourselves) he comments many non-philosophers will be astonished by the extent to which the notion of “what it is like to be” has dominated the philosophy of the mind in the modern era. Thomas Nagel popularised the discussion with his famous paper “What it is like to be a bat: “(No) matter how the form (of phenomenal consciousness) may vary, the fact that an organism has conscious experience at all means basically, there is something that is like to be that organism. There is something like to be a conscious being, whereas where there isn’t something like it is to be as a conscious being would rather obviously not apply to a pile of rocks.

 

So that philosophers have correctly deduced, in relation to consciousness, you can’t have simply functional connections between inputs of experience and outputs of behaviours. Rather obviously there needs to be something in between- hence Qualia. But there is also a need to distinguish between intransitive consciousness “which is a matter of being awake rather than asleep or otherwise unconscious “and transitive consciousness" which is being conscious of something or other. These quite different modes of consciousness -and intermediate ones, like being tired - tend to be conflated with “what it is like to be” talk. Hence the notion of Quale - singular of Qualia - equivocates between what it is like for a person to have an experience and experience itself. Page 95 - Seeing Ourselves 

 

While this is true it misses the point of "what it is like to be the immaterial representations inherent in feeling pain compared to the instant recognition of a material object such as a tree. Therein we can only say what those material things are whilst rather obviously you don't have any representations of what it is to be. Hence, it follows on, you can't understand what consciousness is by merely gathering facts about things. Page 96 Seeing Ourselves. 

 

Furthermore, it has been proven blind people from birth can't describe colours, so trying to explain to such a person differences in hue by reference just to the facts isn't possible. Similarly, then he applies the argument against the neuronal based mind philosophers - how can the observation of neuronal activity and unobserved experience give rise to consciousness? 

Tallis continues on in this vein with numerous examples - such as is there something like it to be a brain which all invite the same conclusion- they fail to translate back to an “am”. For instance we can get an accurate idea of brain functionality to identify where the older emotional type feelings come from and where abstract thinking and or consciousness becomes realisable in the frontal lobes. But none of that translates to the brain knowing that - to have a knowledge of itself ?  

Tallis then makes this point emphatically-  my brain is as ignorant of the fact it is inside my skull as my left kidney is of its status as a pair !!. 

 

He closes in on a profound mystery - How does the "I am" take root, flourish, or suffer, in, or courtesy of, the "it is” of the body? Page 101 Seeing ourselves - I am and it is: Persons and Organisms. 

 

Summing up I believe one can reasonably conclude there isn’t a theory of consciousness in respect to Qualia or related to neuroscience notwithstanding they offer various appealing hypotheses.

That thought takes me back to the heading we are neither apes nor angels and to Tallis’s chapter entitled I am and it is: persons and organisms. 

 

Herein he returns to the theme of intentionality that ensures there is a significant space we occupy that is distinct from nature and the animal kingdoms whose greater reliance is noticeable on the environment. He makes the distinction between the self which has or even ‘owns’ -it’s experiences, encountered as something in - itself, distinct from the experience and, indeed , from the subject of the experience.

 

That first order of intentionality is experienced by the upper echelons of the animal kingdom but a much higher level of uniqueness in intentionality applies to humanity. He then references what he calls ontological snobbery: hatred of the body. We are of course, like all living things inseparable from our bodies, so you rather obviously cannot have one without the other except of course you can have body and person. The bodily contempt goes back to platonic references where human beings were regarded as an unstable mixture of soul as a substance and a body able to conflict that of the souls knowing as in wisdom. 

 

His concluding thoughts are that we need not see ourselves as mere organisms as opposed to embodied subjects, for otherwise we overlook what is interesting about ourselves- in other words how we see ourselves! Our embodiment spans the huge, so far elusive, human being between the person and the organism. This -he concludes is the irruption of the conscious subject within a mindless universe and, as a result, one discovers the business we have unfinished here is, alas, unfinishable, for we shall have moved, beyond the limits of polemic, to the realm of mystery. page 101 -Seeing Ourselves.  

 

I think this is a good point to conclude stage 2. page 101 -Seeing Ourselves.  

 

In stage 3 I will cover: Human Being: in and out of time, the elusive inescapable self and the mystery of human agency whilst alternating to the idea of the collective mind argued by Llinas. 

 

Conclusion and questions 

What do we think of the idea of Qualia? Can it be regarded as a viable construct to explain consciousness or as mind philosopher Danial Dennett proposes is it illusory? Is it necessary or is something similar essential or not as a solution to consciousness? How do we feel about the strength of argument or otherwise of the evolutionary journey argument culminating in the enhanced interaction of neuronal networks resulting in the creation of the central nervous system? What about the objections by Ray Tallis to the brain lacking a knowledge of itself – as in what is it like to be a brain?  

Do we believe that consciousness remains the hard question of science?  Can we reliably abandon the Cartesian mind body separation (dualism) as proposed by Descartes' philosophy?  Any further thoughts on how we see ourselves? How do we see ourselves as distinct or otherwise as part of the universe? 

Monday, November 15

Mind theory: seeing ourselves -part 1

I am providing a summary to support initial discussions facilitated by two distinguished scholars. 

Both Raymond Tallies -“Seeing Ourselves” published in 2020 and Rodolfo R Llinas -“I of the Vortex” published in 2002 provide contrasting commentary.    

Author Profiles and summary background.   

Raymond Tallis believes we are both part of nature and apart from it. He asserts it is only when we have broken away from dogmatic religion and scientific naturalism that we will find ourselves on the threshold of unfettered inquiry- into ourselves, the world we have built and the universe into which we have built it - and then there may be some hope for salvation.

He has an interesting background, as a Professor of Geriatric Medicine and a fellow of the Academy of Medical sciences in recognition of his research into clinical neuroscience. In 2006 he retired to become a writer and developed a rather obvious passion as a philosopher. I became interested in his ideas as he wrote a regular interesting column for ‘Philosophy Now’ entitled “Tallis in Wonderland”. I also have also recently enjoyed reading his publication ‘In Defence of Wonder’.

Rodolfo R. Llanas, is considered the founding father of modern brain science and presents his evolutionary view as to the nature of the mind. According to the summary provided, he traces the evolution of the mind through a primitive animal called the “sea squirt”. This exotic creature receives sensory information about the surrounding environment. 

In my view he provides a credible foundational beginning for the nervous system which has evolved to ensure active movement in animals. His commentary ably demonstrates how the environmental issues allow a creature to safely move on by anticipating the outcome of each movement- from incoming sensory data. This predictive capacity becomes the most likely ultimate brain function- within the 'self' to house predictive capability. Moving on to the current view of consciousness, he describes energized oscillation of neurons as the the heart of his theory-  many neurons, possessing electrical activity, in three minute voltages across the cell membrane. On the crests of these oscillations occur large electrical events which are the basis for neuron to neuron communication. He describes this mind activity as like cicadas chirping in unison, a group of neurons oscillating can resonate in phase with a distant group of neurons. This simulator of neurons is the neurobiological root of cognition. Through the internal state that we call the mind it is guided by the senses, but it also generates by way of oscillations within the brain. Thus, in a certain sense he maintains reality is not an “out there” but rather we live in a kind of virtual reality. 

In summing up he is a philosopher of the mind who developed his comprehensive synthesis based on an elaboration on neuronal integration and synaptic transmissions. As such it represents a highly credible and interesting theory. But nevertheless, from my perspective, it does require a bit too much of a leap in faith, to seamlessly translate into our rich existential conscious experiences.    

Introduction.

I have attempted to include the essential elements of the respective author’s views which predominantly references the earlier sections. Notwithstanding they mostly form the backbone of later elaborations. I will issue a subsequent discussion paper for the remaining sections down the track. 

However, it is to be noted the summary on Tallis will be significantly much more comprehensive simply because his book is much larger.     

At the outset, to reiterate, the major difference to be noted concerns the approach taken by Llinas, which, although it represents an interesting theory, does require a leap in faith in my view, to accept his theory humans engaging in activities as diverse as sharing information, creating art, literature and so on arose via the evolutionary journey. 

However, in part 2, I will take a closer look at more of the respective abstract issues later on in the respective publications.  For instance in the latter part of Tallis's book he talks about the elusive inescapable self and finding meaning in life. Although Lianas tends to stick to the more concrete matters he does also talk about more abstract matters later on. There are some interesting commentary on patterns, emotions, qualia and collective memory.  

These aspects will be covered in a subsequent post once I have established the foundational theory for the respective commentaries.      

Turning to Tallis his quest, whilst accepting the monstrous, glorious, unexplained and strange form of our identity and selfhood is to see ourselves in a new light in the 21st century. In the process he argues against the isms such as: scientism, naturalism and the obsessive emphasis as he sees it on Darwin's evolution.  

 Against Naturalism - neither ape nor angel. 

Tallis argues against the seductive false lure (as he sees it) that follows on in rejecting the image and handcrafting image of a GOD, (as in we are created in GOD's image) to falsely place reliance in the processes observed through nature. Under that scenario humanism and naturalism must be close allies- a proposition Tallis rejects.

He defines naturalism as any entities described by physics or as biological beings.

His initial question is to ask how we can entertain such a total reliance on natural theory, bearing in mind the vastness of our world and the tiny slither we have in direct contact with it. He notes the response of the scientific community has been that the answer is within those physical laws of nature that verify the materialistic view. But the problem is, when we go in search of those answers we find they are rooted in materialistic naturalism involving panpsychism- the presence of mind that must be present through the universe, which by no means can be substantiated in any meaningful or logical manner.   

But Tallis’s main thrust is his objection to evolutionary theory to posit we are just another biological being.  

Whilst acknowledging his own commitment to science, inclusive of his own research into neuroscience over many years and as a scientist, he asserts there is no hard evidence against our uniqueness as human beings, 

He acknowledges himself as a committed Darwinian, aware of the early awakening when assumptions were made about our first primate ancestors who began to walk upright several million years ago. Thereafter that liberation afforded additional freedom in the use of the human hand and the domination of the visual senses. But within that process no credible explanation exists for our ensuing complexity, other than vague links to adaptability. He does not argue against the idea of consciousness that is evident in the animal kingdom, but rather sets out his defence of our human uniqueness that sets us apart.

I don’t propose to detail all of his concessions about single cellular to unicellular and ongoing complexity or the numerous other analyses. Rather, to drill down into his day to day examples of experiences indicative of our uniqueness. For instance he asks the question, if an animal has one identifiable sense of upper level consciousness, why isn’t it apparent in other aspects of its life in everyday occurrences? Wouldn't it exhibit that unique quality more consistently over other life forms in ongoing examples in its life cycle? Some of the more important distinctions will be covered in later chapters such as the aspect concerning the ability of humans to think’ in respect to tensed time, that makes this point even more convincing.

But the fact is, he acknowledges, by studying in much more detail the day to day interactions of the upper echelons of the animal kingdom one gets a far greater insight into our own uniqueness. This aspect was expressed by Jane Goodall. It’s only in understanding the real ways in which chimpanzees and men show similarities that we can reflect, with meaning, on the way in which men and chimpanzees differ. And only then can we begin to appreciate, in a biological and spiritual manner, the full extent of man’s uniqueness. 

Darwinite’s 

To reiterate, Tallis opposes evolutionary theories that propose we can be seen as simply highly evolved organisms. He talks about a simple example of cooking a meal, where a group sits around the dinner table which even at this ordinary aspect of existence therein one observes a vast number of choices. Those multiple choices, inclusive of the use of grammar, the celebratory or ritualistic aspects can’t currently be explained by evolution, according to Tallis. They are largely absent in the feeding habits of the upper echelons of the animal kingdom just as there are no direct credible links in our evolutionary journey to their existence.    

“I of the Vortex”

At this point in the discussion paper it is opportune to introduce the author’s ideas. Beginning with the earlier chapters, they are mostly technical in nature, but I will attempt to summarise so as to ensure the context is maintained in the story so far. 

He clarifies some notions when dealing with the scientific aspect of the mind. Firstly he is a monist who sees the mind as the product of the brain which is in contrast to Tallis. In other words the mind and the brain are inseparable. All sensory functionality occurs in the brain which he further classified into motorised sensorial images. He summarises his idea of the brain as a living entity that generates well defined electrical activity. Mystery of the mind he asserts is tied up with all of the functionality in the various processes involved in thinking, consciousness and dreaming which are removed from the external world and purely mind dependent within the brain. His links movement and mind as deeply related: different parts of the same process. He then gives a historical account of this thinking to move on to the intrinsic nature of brain functionality, given the independent nature of the central nervous system. The next step is to make the transition to an explanation of neuronal functionality, their oscillating nature, resonance and rhythmic coherence, of which the motor aspect is driven by muscle force. There seems little point in doing more than a cursory acknowledgment to this functionality given its technical aspects can be assumed to be correct and don’t deal directly with the question of how we see ourselves. What is of interest is how he views evolution as leading one down the path to an explanation of how the mind simply arose.

Herein his theory is opposed by Tallis, so a brief explanation is in order. According to Llanas this transition occurred at a critical time to support life as it moved on to multicellular organisms which were then dependent on a central nervous system for survival to allow for movement as distinct from plants for instance. He introduces the sea squirts with a primitive central nervous system by way of example and concludes the evolutionary development of a nervous system is an exclusive property of actively moving creatures. He then moves on to the predictable qualities that give advantage and control of movement, resulting in its efficiency and in tune with its regulatory nature and synergies that save time in the mind's development in the brain.

 To summarise at this point: predictability is crucial through sensorial motor dependent formulation of the external world which is contextualised in the brain and secondly this operation is carried out in such an efficient manner as it conserves energy. Page 38 'I of the Vortex'.  

Turning now to Tallis we find he is indeed highly critical of this thinking 

 Neuromania 

Tallis contends the most profound differences in humanity lie in our uniqueness and that the mind is not just the product of the material brain. This is apparent in the freedom and inherent ability to help one another and to share experiences so as to add to our accumulated knowledge. Neuromania, as he calls it, on the other hand, makes the outlandish claim consciousness is no different to the beasts in that it is solely the province of brain functioning. So that neuroscience thinks it is on the verge of unlocking the key to what human nature is, possibly by simply peering into the darkness of the human skull using techniques that record neuronal activity. The impossibility of accommodating consciousness with evolutionary theory is summarised by Tallis as follows:

·  The impossibility of accommodating the emergence and elaboration of consciousness within evolutionary theory;  

·  The failure of neuroscience- ultimately a branch of physical science – to account for the intentionality of mental contents. More on this later

·  The neurologically inexplicable transformation of sense perception into propositional or factual awareness and understanding that is amenable to unlimited elaboration into a vast body of knowledge; and  

·   The development of a human world, in which one actively lives, offsets from nature. . 

 

Pages 46 Seeing Ourselves

 

Intentionality

For Tallis, intentionality is a crucial element to his proposition that marks a distance of conscious beings [whether human or non-human} to the material world, but in relation to humans opens a much greater difference to that of the animal kingdom. Intentionally he defines our relationship with our bodies, modes of being in time, selfhood and agency. He defines intentionally as the power of the mind to be about, to represent, or to stand for, things, properties and states of affairs. As per the definition by Franz Brentano 

When we refer to things as in our perceptions or memories they have an “aboutness”: they are directed to or about something sensed as being other than perceiving. Mental phenomena contain the object by being about an object intentionally within themselves. That is not to confuse the ordinary use of the word. The end result is that of a shared world experience and not just me. In that sense intentionality is an effective rebuttal to the neuronal argument which can only be of itself and conscious experiences about a world other than that which has provided a vast literature.

What Tallis argues is the neuro-philosophers such as Daniel Dennett, don't seem concerned the vast majority of inputs into the senses don’t finish up in our consciousness but in the sub-consciousness. They subscribe to the belief there can only be one kind of stuff namely matter, which is further endorsed by John Searle. Tallis responds that we can prove the falsehood of this entire of materialism as in all there is matter by simply seeing an object such as a glass in front of you. 

He explains his thoughts as follows: 

Casual input into my brain arising from the glass 

Light energy entering into eyes and eventually stimulating my visual vortex 

Result is a set of events in the glass 

Let Cause =C at time T 

At the start then of a causal sequence terminating in neural activity is the visual cortex 

Effect E= at time T 

The inward casual chain from C to E is a necessary condition of my true experience that there is a glass in front of me. However, it is not a sufficient condition, or at least a sufficient explanation, of my experience, for there is a second aspect of that experience, namely the “aboutness”. 

Hence the events previously described have to reach back to the glass via the intermediate events, to the events C in the glass at T in order to be about the glass. The light getting into the eye, passing from the object to the eye - which we might call rele- reception and the gaze looking out at the object out there - which we might call tele projection are not the same. There is nothing in the explanations of the brain that provides a satisfactory explanation of the interaction between the glass and the light incident upon it. A similar example is provided via billiard balls colliding with one another. Pages 51 ‘Seeing Ourselves’  

 

Finally, on evolution Thomas Nagel expresses the view Evolution may explain why creatures with vision or reason will survive, but does not explain how vision or reasoning are possible. The possibilities of minds forming progressively more objective conceptions of reality is not something the theory of natural selection can attempt to explain …..since it does not explain possibilities at all, only selection.

For further reading https://www.frontiersin.org/articles/10.3389/fpsyg.2018.02091/full

 Discussion points 

Bear in mind at this early stage there is still a lot of ground to cover. Nevertheless there is ample room for initial discussions as to whether or not we believe the materialistic view of ourselves is valid or not. That is, do we see ourselves solely as organisms generated by evolutionary forces or not? Does that matter ?  

If we are of either view how do feel about the methodologies presented ? What do we think about a non-physical spiritual view? If that be the case then the materialistic view might argue equally that the neurons then pose mysterious personal qualities?

Which view do we feel more comfortable with and the reasons?

Can we have a mixture of both?

 

Monday, November 8

George Berkley’s legacy - a logical & common sense GOD

         Introduction

This discussion paper concerns George Berkeley, (1685-1753) who was an Anglo-Irish Anglican bishop, philosopher and scientist. Berkeley felt the need to challenge the mechanised world view that took hold during his time due to the influence of the scientific revolution which challenged people’s beliefs.   

The Scientific Revolution   

Newton had explained why the orbits of the planets are ellipses rather than circles and much more including the theory of gravity. As you would be aware Newton demonstrated instead of two forces underpinning planetary movements there was only one, represented by the force of gravity. His unifying laws then accounted for the position of the planets. Newton himself was also a theologian, but from a metaphysical point of view he didn’t believe in GOD's day to day control of the universes except to concede he might intervene from time to time. 
Berkeley was alarmed by the emergent world view which regarded the world as analogous to a giant machine and the growing scepticism and non- belief that accompanied this development.   

 

Berkley response first ridiculed    

His response was to propose a simple idea that rejected the idea of existence of matter in the world since that involved abstract thinking. Rather he proposed the world we experienced through the senses represented reality. It was a matter of common sense to Berkeley our reality could only be what was perceived or what was perceivable. He concluded one can’t think of things in reality as in an abstract manner in terms of geometric shapes as was proposed by Descartes and the enlightenment philosophers. It is not that Berkeley is saying they are inconceivable, rather they are not perceivable as reality. They may represent a reality in some cases when they coincide with the perception through the senses.      

 

Rather, he wanted people to feel they could trust in their senses and argued there were no secondary or third related ways of perceiving things according to the enlightenment philosophers, but only that which relates directly from our experiences. Those ideas, arising from the perceptions are made possible by virtue of the consistent laws of nature as bestowed by GOD.  Naturally enough Berkeley’s philosophy was his defence of belief in GOD as a logical philosophy, so, in turn, he could mount an attack on atheism and scepticism that arose from the newly experienced scientific age. The denial of the abstract way of thinking and to propose all we experience of the world through the senses meant one must answer the question: what is the cause? The cause of course was spiritual as in GOD.     

 

However his ideas were initially ridiculed by the intellectual establishments which caused him to write his subsequent dialogues in a manner similar to those by Plato to Socrates in order to explain his ideas more comprehensively and in an attractive manner.                        

 

Berkeley’s idealism  

Idealism in philosophy differs from the everyday use of the word when you say something represents an ideal solution. Rather idealism in philosophy broadly speaking references ideals that are opposed to mass as in a materialistic world. Idealism references a non-material world comprising mental states or mental substances or spirits. Of course not all idealists fit neatly into that category.
 
Broadly speaking Berkeley’s idealism was that all there is, is ideas and collections of ideas that make up our immaterial view of the world.
 
He proposed that identifiable objects are linked via our minds' perceptions to those things we have previously experienced. Therefore you cannot be aware of anything as in perception unless you have had a prior experience. He does not deny the existence of those things that have not been perceived, so long as they are perceivable.       
 
Summing up Berkeley’s philosophy and his critics  
 
Berkeley was an empiricist as he asserted all human knowledge was derived securely from our senses or could be inferred from that experience.   
He does this logically, both in respect to direct material objects and those that are either feeling based. In both cases he seeks to demonstrate the common sense logic of this proposition. Firstly in relation to such things as colour, taste, smell, heat, shape and size etc. they principally involve either pleasure or pain and so he argues they are unmistakably all mind dependent. Rather obviously they cannot reside in material objects. In relation to primary qualities the same principle as objects can appear differently due to the lighting or space. They appear to be big or small, demonstrating they are mind dependent. Berkeley argues the subsequent variable experiences of both the primary and secondary qualities arise in the mind and cannot be independent of it. What you experience of the world is the reality of it but you can’t experience something as abstract as mass. In relation to abstract thinking of course you can talk about it or use symbols or as in maths apply it and so on. It might coincide with what you can conceive through the senses as was bestowed by GOD. There is a spiritual element which comes from GOD in relation to the infinite mind thoughts whilst the finite experiences come to us via the senses as per the laws of nature decreed by GOD.                

  

His Master Argument
Additionally to the above arguments his so-called master argument uses an Aristotelian syllogism to prove the falsehood of materialism.
(1) We can conceive of a tree existing independently out of all minds only if we can conceive of the tree existing unconceived.
(2) But an unconceived conceived thing is a contradiction.
(3) Hence we cannot conceive of a tree (or anything else) existing independently and out of all minds.

 

Although this argument may appear to be convoluted, one way to understand his reasoning is to say it is not possible for a tree to exist outside of all minds, because we would need to think of an unconceived tree, which is not possible. The reason being as soon as we try to conceive of an unconceived tree, we then have conceived of it. However, Berkley makes no distinction between the act of perception and the intent of the perception.
In that respect his master argument may falter.
In the above example one might argue:      
(1) We can conceive of a tree existing independently out of all minds only if we can conceive of the tree existing unconceived.
(2) We can conceive of an intent to perceive of an imagined tree
(3)  We can have a perception of an unconceived tree.  

 

Even so the question of intention in philosophy has been debated and the fact we can conceive of an intent to perceive of something is by no means assured. Philosophers continue to argue as we simply don’t know enough about complexities of the mind to form a logical conclusion.      

 

Critiques of Berkeley  

Other thinkers, struggling with questions as to how we perceive reality, took the opposite position. The materialists argued that nothing exists but matter. Then we have the dualists, such as Descartes who suggested ideas and matter were two discrete things.

 

To reiterate, Berkley came up with a simple solution that was hard to refute which assumes our accessibility to things ‘in the world’  is from the collection of ideas forming in one’s mind about them, so that  Berkeley’s assertion is it is the mind, not matter, that must be the fundamental reality.

 

His philosophy can be regarded as one embracing immaterialism- in opposition to the materialistic view which proposes physical objects or things we directly experience in our life. The critique of Berkeley’s philosophy came from the analytical philosophers. Principally they were G E Moore and Bertrand Russell. Moore refuted Berkeley’s immaterialism with a simple example of holding out his hand which he acknowledges without the need to identify it or conceptualise it into his mind. It begins instinctively from recognition by the infant. Most of Moore’s criticisms are also on the basis of common sense, just as there were for Bertrand Russell. They contended mountains and trees and similarities existed long before our minds began to think about them. One can conceptualise things in the mind that haven't been seen and material objects can exist independent of the mind. The best representation we have of the world is the one we see, as in being in the world. But these arguments appear weak since Berkeley’s response would have been that objects only exist as far as we can experience them as mental substances. He doesn’t refute the prior existence of things that have not been perceived so long as they are perceivable.     

 

But the modern day view is to reject epistemology (theory we can obtain specialised knowledge as in knowing allied to philosophy) and analytical philosophy as views analogous to an unstable building erected in the absence of any secure foundations. 
Beginning with Heidegger his idea (as in being in the world) is we can’t step outside our existence and view it independently as those before have suggested. Hence, it makes no sense to talk about subjects (us) and objects as if we can do this independently. Rather, being in the world means we don’t think about ourselves as if we are remote from it because we are in it and can only talk about our interaction within it so to speak. Heidegger talks about our engagement in the world with equipment (as he calls it) is a matter of having to deal with it in our existence.

 

To a degree, however, Heidegger’s phenomenology is in tune with Berkeley’s.
Pragmatic Philosopher Richard Rorty asserts we only have the sharpened philosophical tools at our disposal and should not be deluded into thinking they provide any privileged representations or equate to any specialised knowledge also available elsewhere. 
Modern day philosophers such as Hubert Dreyfus and Charles Taylor emphasize knowledge is much more than just the representations we formulate. We gain knowledge of the world because we are integral to it as in both a hands on bodily engagement and movements within it.

 

Conclusion

The legacy that Berkeley leaves us is to encourage us to jettison the idea of any Cartesian duality, as we elect to debate his view of reality with those of the materialistic mindset. Although his assertion of immaterialism does sound counterintuitive it is very difficult to refute. Some might say that our lack of knowledge renders such assertions without a secure foundation.
However, his thinking provides ample food for thought and discussions. After all Einstein maintained all there is is energy, so that inherent in this principle materialism remains challenged.