I thought that Locke, with his reputation as one of the first empiricists, would have just stated the obvious: That philosophers should believe the evidence of their senses like everyone else has always done. Mere words, with which we do our logicking, stem at least partly from our senses. This would have begun a liberation of philosophy from the logicking madness that had gone before.
But no, he got there by such a strange route that I had greater difficulty understanding him than any other philosopher I had tried. He felt it necessary to interpose the theory that sensations give rise to ‘ideas‘ in our minds, and that the sensations and ideas do not necessarily represent the real thing out there. So there was still room, it seems, for External World Scepticism — that we don’t really know the outside world!
Anyway, here is my comprehension of Locke’s epistemology, as I have cobbled it together as best I can in order to make it a whole:
His main concern, like that of many philosophers of the seventeenth and eighteenth centuries, was Epistemology — what knowledge exactly is and how we get to it.
(From here🙂 On the Continent of Europe in the 17th and 18th centuries, philosophers continued with an abstract Rationalism — a deductive reasoning in order to reach true Knowledge. But Locke was impressed that British scientists like Francis Bacon, Isaac Newton, Robert Boyle and Thomas Sydenham had acquired knowledge by way of concrete observations of nature and by experiments. Many of them were his friends in the Royal Society.
So the goal of his An Essay Concerning Human Understanding (1690) was to establish a theory of knowledge for these new sciences, and to clear the ground for even more observations and experiments. According to my understanding of here, it seems that Francis Bacon, some 90 years earlier, had already started to do this and that Locke pursued it.
Locke divided the whole of knowledge (not only what comes from observation and experiment) into three: There’s intuitive knowledge, which amounts for example to knowing that 5 is greater than 2 (although this to my struggling mind strays into the demonstrative knowledge of mathematics), and to knowing that one exists. (So it seems that Locke regarded his own existence as being a matter of intuition rather than of having to deduce it logically from the fact that he was thinking, as Descartes did.) Locke thought that intuitive knowledge was the highest and most immediate kind of knowledge. (What does ‘highest ‘ here mean?) Then there’s demonstrative knowledge, which comes from a line of reasoning in logic or mathematics. And finally there’s sensitive knowledge which does come from one’s senses.
One’s mind is initially empty but then gets furnished with ideas of two sorts: from sensations we obtain ideas of things that seem to exist in the external world; and then from reflections we have ideas of the mental operations that we do on these lideas of our sensations. (That last interpretation of mine on ‘reflections’ is the best understanding I can presently get on what this site was saying.)
But from where, I ask, do Intuitive Knowledge and Demonstrative Knowledgee come from? I think that I come to the conclusion below from other sites that Locke thought that these derive from sensations too.
Tabula rasa is Latin for blank slate. Locke’s theory was that a baby is born with a void for a mind, and that knowledge gradually fills it as the child receives sensations.
From here and here: So, to continue with sensory perceptions: after seeing a red and fragrant rose, one’s mind can form ideas of redness and fragrance without perceiving another actual rose. Locke then distinguishes between simple and complex ideas. The former come from one sense alone, such as bitter and spicy from oral taste. Other simple ideas are those of colour, sound, smell , shape, size and solidity.
In complex ideas the mind participitates by combining perceptions from different sense-organs. An example (given perhaps by Locke himself) is the complex idea of God which is made up of simple ideas like power and goodness. (But which different sense-organs do ‘power’ and ‘goodness’ come from?)
From All Knowledge Begins with Sensation, by Kenneth Shouler, in what used to be ‘netplaces’: Sensation or ‘sense experience’, as Locke calls it, presents sensible qualities to the mind, such as coldness, blueness, and softness. When the mind reflects on these sensations, it receives a second set of ideas pertaining to these sensory operations. This seems to consist of such mental operations as perception, thinking, doubting, believing, reasoning, knowing, and willing. (Mmm, that is not quite clear enough.)
One doesn’t only think about what one has experienced. One can also think about things one has never seen such as dinosaurs or unicorns. So Locke’s claim must be about the ultimate source of our ideas. He accepted that we often mentally manufacture complex ideas by compounding simpler components. My idea of “unicorn” may be compounded from the ideas of “horse” and of “single spiral horn” both of which come from experience. Locke devoted Book II of the Essay to showing that every idea could, in principle, be derived from experience.
But there is another difference between the ideas: the colour of the wall in front of me seems to vary according to the ambient light and the state of my eyes, while its solidity persists independently. It is said here that, following Galileo and Boyle, Locke explained this difference in corpuscularian fashion, i.e. that all matter is composed of tiny particles. (But that explanation, I feel, needs further opening up.)
Here is another explanation of the difference that Locke put forward: Sensations that vary are excited by the object’s secondary qualities.
Its primary qualities are its real qualities, its intrinsic features, those it really has. They are measurable and objective. They are in the object itself, including the bulk, figure, texture, and motion (as Locke called them) of its parts. (Essay II viii 9). Primary qualities are inseparable from the object even when the latter is divided into parts too small for us to perceive. They are independent of our perception of them.
The primary qualities of the rose include all of its quantifiable features, its mass and momentum, its chemical composition and microscopic structure. These are the features of the thing itself.
Such primary qualities include solidity, extension, shape, motion, rest, and number, all of which excite exactly similar ideas in our minds. (These ideas of course, according to Locke, are only mental images and not the objective reality of the primary qualities themselves as they exist in the external world!)
Secondary qualities, on the other hand, are not actually in the object. Our ideas of them are subjective to oneself. Examples are the color, sound, smell, and taste of objects. These ideas change according to circumstances, as for instance when porphyry changes its colour in different lighting. (Alright, so these ideas are changeable but they are excited by the object itself and are changed in the same way for everyone, so how can Locke say they are subjective to oneself? That’s an example of brilliant philosphizing by mysel!.)
The secondary qualities are simply ideas that the object produces in me. They are merely the effects of the primary qualities of its corpuscles on my eyes and nose. The color and smell, like the pain I feel when I stick my finger on a thorn, are not features of the rose itself. (Oh! now Locke is saying that the secondary qualities are simply ideas inside oneself that are produced by the object’s primary qualities!)
The following paragraph, derived from here and here, doesn’t make sense to me: The distinction between primary and secondary qualities is important for representative realists who think we are aware of objects only via ideas that represent them. Descartes and Lock are examples. Many instances of perceptual illusion can be explained by reference to the way secondary qualities depend upon our sensory organs. It also accounts, it is said, for memory, (but surely memory simply depends on conjuring up an idea of any kind). It may lead (as with Hume) to External World Scepticism, which says (would you believe it?) that you can’t prove logically that there’s anything in the world outside that actually corresponds to what your senses and hence your ideas tell you inside your mind. (so logicking with words is a more reliable proof than one’s senses!)
Many instances of perceptual illusion can be explained by the way secondary qualities depend upon our sensory organs, but the possibility of accurate information about the primary qualities is preserved. The botanist can achieve detailed knowledge of the nature of roses, of their primary qualities, but that knowledge is not necessary for my appreciation of their beauty which comprises secondary qualities.
(From Primary Qualities, Secondary Qualities, and Substanceby Kenneth Shouler, Ph.D., in netplaces, which no longer exists:) Locke also postulated a third quality of objects on top of their primary and secondary ones. The third quality is that which causes changes in the primary qualities of other objects, like the sun has the quality to ‘make wax white, and fire to make lead fluid.’ (I think this should be ‘changes in secondary qualities’ and not ‘primary’).
Locke also believed in the existence of ‘substance’. A thing’s substance is a substratum underlying and supporting its primary qualities. The word ‘substance’ literally means ‘standing under’.
But believing in a ‘substance’ provided difficulties for the empiricist, because it’s not perceivable by the senses. In other words, what is this substance like? Locke confessed he couldn’t answer — he called substance an ‘I-know-not-what’ thing. He therefore falls into the definition of a ‘metaphysical agnostic’, in saying that the ultimate nature of reality is unknown. You know only the primary and secondary qualities of an object, but the substance itself remains unknown. David Hume maintained that Locke’s idea of substance, and also of the self and of God, cannot be known from experience.
Locke wondered whether animals perform reflection on their simple ideas of sensation. Descartes had rejected the possibility of animals thinking but Locke thought it was only abstraction that animals didn’t do. (‘Abstraction’ seems to be defined as the operation most crucial in forming the ideas of mixed modes on which morality depends, but what ‘modes’ exactly are is presently beyond me.)
So “hard,” “red,” “loud,” “cold,” “sweet,” and “aromatic” are ideas of sensation, while “perceiving,” “remembering,” “abstracting,” and “thinking” are ideas of reflection. “Pleasure,” “unity,” and “existence,” Locke held, are ideas that come from both sensation and reflection. Everything we know, believe, or think, is made up of ideas of sensation and reflection and nothing else. (But again I ask in my stupidity, where do intuitive knowledge and demonstrative knowledge, as Locke mentions above, come from. How do these come from sensation and reflection on sensation?)
Perception of ideas through the senses, and their retention in memory, Locke held, are ‘passive powers of the mind’ beyond our voluntary control ‘and heavily dependent on the material conditions of the human body’ (whatever that means).
The active powers of the mind, on the other hand (are these the ‘reflections’?) include distinguishing, comparing, compounding and abstracting, so the mind has the power to develop new, complex ideas from the simple ideas provided by experience. (What about the “perceiving,” “remembering,” “abstracting,” and “thinking” that he had mentioned two paragraphs above here ?)
These complex ideas are of three or four sorts for the philosopher: Firstly Mode, which seem to be contrasted with Substance and Essence. There also seems to be the complex idea of Relation. (All of that is presently beyond me — where are the reflective ideas of ‘perceiving’ etc. and ‘distinguishing’ etc.that he had mentioned above?)
From here: According to Locke’s Essay concerning Human Understanding I i 8, his concept of ‘idea’ included concrete sensory images, abstract intellectual concepts, and everything in between. The colors and shapes I see before me are ideas, and so are my hunger, my memories of the ocean, my hopes for my children, the multiplication tables, and the principles of democratic government. Ideas, then, are the immediate objects of all thought, the meaning of all words, and the mental representations of all things. (That’s what this site says. It seems to me that Locke’s ‘idea’ included everything inside the mind.)
From here (which may no longer be available): I’m not sure whether Locke subscribed to External World Scepticism, at least for a time. But he did say, eventually, that there’s something called ‘Sensitive Knowledge’ which implies that he did come to believe that the senses do give us knowledge of the external world. But then again, some philosophers later pointed out that this conflicts with his earlier view that knowledge amounts to perceiving the agreement or disagreement between our ideas (but I have presently no idea what on Earth that latter means).
But there is another important question of Locke’s: Where do we get all of these ideas which are the content of our knowedge from? (I ask: is Locke now asking where we get Sensitive Knowledge from, and perhaps intuitive and demonstrative knowledge too?)
Most of Book I of the Essay is devoted to a detailed refutation that the pure principles of logic or metaphysics or the practical principles of morality are inscribed on our minds from birth. (So, I ask, was Locke saying that not even the intuitive and demonstrative kinds of knowledge come from innate sources? I had thought that Quine was thought to be innovative in the 20th century in saying that analytic statements are based on experience.)
From here: Locke pointed out that children and mental defectives do not assent to the truths of intuitive or of demonstrative knowledge. (But that, I think, isn’t a good argument against truths being innate in the mind, because the minds of both these groups are undeveloped.) But anyway, Locke said, even if everyone did accept these truths, that could be better explained by these truths being self-evident or by shared experience than by being innate. (Essay I ii 3-5)
There may be more on Locke’s empiricist epistemology, his route to knowledge here.
From here: Locke couldn’t analyze every idea that anyone has ever had. But his defence of the empiricist route as the only one leading to knowledge, obliged him to show in principle that each and every complex idea we have can be derived from the simple ideas of sensation and reflection. The clarity, reality, adequacy, and truth of all of our ideas, Locke supposed, depend upon the success with which they represent reality. (That last, almost verbatim, sentence simply means to me that each idea we have must be true to reality. You don’t say!) This site then goes into an example from each category of difficult abstract thought, such as Power, Will and Freedom, Substance, Personal Identity, Words, Knowledge and its Degrees, and others, to show, I think, how each of these derive from sensatons.
I look at Locke, at his highly developed arguments about the simple and complex ideas arising from sensation and reflection, and my mind boggles at its development of empiricist logicking and at its complete unnecessariness.