1. Philosophers: John Locke and Bertrand Russell. 

2. Indirect realism is composed of four claims. Firstly, the realism claim: that there is a mind-independent world, populated with mind-independent objects and properties. Secondly, the indirect access claim: that our access to this mind-independent world is always cognitively indirect, i.e. by inferences from knowledge of mind-dependent sense-data. Thirdly, the causal claim: that sense data are caused by mind-independent objects and properties. Finally, the representative claim: that mind-dependent sense data represent the mind-independent object of perception. (To be committed to representation is not to necessarily to be committed to resemblance. Sense data may represent mind-independent objects in the way that contour lines represent hills and mountains, i.e. not as a resemblance.) 

3. The indirect realist answers the epistemological question as follows:  

“We have (cognitively) indirect access to the way the mind-independent world around us is. We are only ever (cognitively) directly aware of the mind-dependent world of sense data. From sense data it is possible to form inferences about the existence and nature of the mind-independent world. It is always necessary to know mind-dependent sense data first, and the mind-independent second.” 

4. The indirect realist answers the ontological question as follows. 

“There exist two worlds, the mind-independent world of physical things with their properties, and the mind-dependent world of sense data. The mind-independent world is reality and the mind-dependent world of sense data are appearances. I know the mind-dependent by introspection infallibly. I have knowledge by acquaintance with the mind-dependent. I know the mind-independent by inference. This knowledge must be fallible (though it may be reasonable).” 

Locke’s primary and secondary qualities distinction 

1. The primary and secondary qualities distinction is offered by John Locke in support of indirect realism. To understand the distinction, you need to first grasp the science of John Locke. 

2. Locke believed, following the science of his time, that mind-independent physical objects are composed of tiny particles called corpuscles. You might think of corpuscles as similar to atoms. However, there is an important difference between atoms and corpuscles. For Locke, some of the qualities which mind-independent physical objects, say a table, have, are not really possessed by the table, but instead by the corpuscles and their mechanical movement, which make up the table. Today, we would not speak this way about atoms. It seems that atoms, more often than not, do not behave like physical objects, but are rather like little packets of energy instead. Also, atoms interact by forces at least as much as mechanically.  

3. With the science cleared up, here is the distinction. Locke claims that there are some qualities which the mind-independent object has ‘in and of itself’. These qualities are measurable objectively. I can lay down, say, in centimeters, a measure of some of these qualities and, supposing the measurement is done correctly, we would all have to agree on it. These qualities are also entirely inseparable from the mind-independent object. It doesn’t matter what manipulation you perform on the mind-independent object – you might cut it into a billion microscopic pieces – so long as you still have some amount of the mind-independent object, then that quantity will have these qualities. The mind-independent object cannot, therefore, exist through the removal of these qualities. These qualities are known as primary qualities. Finally, these qualities are accessible by more than one sense organ. Typically, I would measure something in centimeters using my sight. But it is possible to image a person measuring in centimeters using their sense of touch. 

4. Secondary qualities contrast with primary qualities. Locke defines them as ‘nothing but powers to produce various sensations within us.’ In a sense, these qualities do not exist within the mind-independent object of perception, but rather arise from the interaction of the mind-independent object and the subject of perception. Secondary qualities cannot be measured objectively. Think about it this way, who is to say, objectively, what the sensation of red should be? Secondary qualities can be lost from the object of perception, when, for example, it is manipulated, say to the point of being cut up too small to see. Secondary qualities are not, therefore, essential to the existence of a mind-independent object. A given secondary quality can only be accessed by one sense organ. For example, the sensation of the color red, could only be accessed by the eyes. 

4. Below are the lists of the two sets of qualities. The primary qualities are said to be the cause of the secondary qualities. We can use one theory of smell to illustrate the point. The smell of a mind-independent object is the result of the interaction of certain molecules of a certain shape with certain receptors in the nose of a corresponding shape. In this way, the shape (primary quality) of the molecules/receptors determines the smell (secondary quality). (Obviously, this example is depending on some modern atomic theory, but that shouldn’t stop us seeing the analogy.) 

5. Two things to remember. Firstly, we have written so far of the mind-independent object of perception possessing the primary qualities. Strictly speaking we should say corpuscles possess the primary qualities if we are to be faithful to Locke’s thinking. Secondly, do not confuse the primary/secondary qualities distinction with the distinction of sense data and mind-independent objects. Locke is clear that we only ever access primary qualities through sense data. We have no direct access to them. 

ISSUES

Resemblance and supporting indirect realism 

1. Locke argues that primary qualities resemble the object of perception, whereas secondary qualities do not. You will recall that when we first introduced indirect realism we noted that the indirect realist does not need to believe that sense data resemble, but only represent, mind-independent objects. We used the example of a contour lines on a map, which might represent a hill or mountain, without resembling one. This way of presenting indirect realism comes from Bertrand Russell. Locke makes a bolder claim, at least, concerning the primary qualities. The primary qualities resemble the mind-independent object. How the height of a table appears in sense data, when checked using an objective measurement, is a true resemblance of the mind-independent height of the mind-independent table. 

2. This distinction between primary qualities which resemble the mind-independent object and secondary qualities which don’t, is used by Locke to strengthen his distinction between the world of appearance (sense data) and reality (mind-independent objects). He would speak of the world of appearance being the world of sensation (secondary qualities) and the world of reality being the world of science (primary qualities). 

3. The existence of a permanent mind-independent world would seem, according to Locke, to be more likely if there be primary qualities. In the previous section of today’s worksheet, we defined primary qualities as those which the mind-independent object has ‘in and of itself.’ If primary qualities are qualities which exist within mind-independent objects, and primary qualities exist, then so too, do mind-independent objects. 

4. As you will see later in this section of the course there are anti-realist philosophers who would like to argue that there are no mind-independent objects, at least in part, on the basis of the veil of perception which would seem to lock us out of contact with the mind-independent, and the apparent subjectivity of our sensations. Against this position Locke argues that the objectivity of primary qualities suggests there is a mind-independent world with mind-independent objects. 

The issue of scepticism 

1. Scepticism is the central topic of consideration in unit 4 of year 12. We will discuss it in more detail then. For now, it is important to understand this much: the sceptic doubts whether our usual justifications are adequate for us to claim to know X, whatever X maybe.  

2. In relation to indirect realism, there can be scepticism about whether, given the veil of perception, our usual justifications, based, as they are, on sense data, are adequate for us to claim to know that the mind-independent world exists. (This issue focused on the existence of the mind-independent world with mind-independent objects, not the nature of it. Though it is perfectly possible to raise concerns about our knowledge of the nature of the mind-independent world. This topic is just not on your specification.) The existence of sense data is compatible with a situation in which the mind-independent world does not exist. 

3. We can rephrase the issue which scepticism causes for indirect realism using the concept of the veil of perception. If the mind-dependent veil of perception is composed of sense data, and a subject of perception never directly knows anything except or beyond the veil of perception, then it must be impossible for a subject of perception to directly know of anything mind-independent. To indirectly know of the mind-independent by supposed inference from only sense data is to do no more than guess. This is because there can be no empirical (by observation) reasons, nor any logical (conceptual) reasons to say that sense data must be caused by a mind-independent world with mind-independent objects. 

4. Let’s unpack the last sentence of the previous paragraph. There can be no empirical (by observation) reasons for inferring that sense data must be caused by a mind-independent world since direct observation of the mind-independent world is precisely what is not possible according to indirect realism. There can be no logical (conceptual) reasons to say sense data must be caused by a mind-independent world, since there is nothing in the concept of sense data which means they must be produced by a mind-independent world, rather than, say, be the material of a dream. Bertrand Russell, an indirect realist himself, sees precisely this problem that our supposed knowledge by perception might be nothing more than a dream. Rene Descartes raises a similar problem using a different example. Descartes askes us why all our sense data could not be produced by an all-powerful demon deceiver and nothing more? He sees no logical reason to suppose this couldn’t be the case.  He points out that this would involve no mind-independent world as it is traditionally understood. 

5. An analogy might be helpful. Imagine you were making a catalogue purchase, perhaps from Argos or through some online retailer. You can only see a picture and a description of the product you are about to buy. You can never the see the product itself before purchase. In this position you have no empirical (observed) reason to suppose that the picture and description pick out something which really exists. Afterall, we have just said you cannot see the product itself. Nor is there any logical (conceptual) reason either, to suppose that the picture/description accurately pick out the product. There is nothing about the concept of the picture/description which mean they logically must pick out a mind-independent object. 

RESPONSES

Locke’s involuntary nature of experience response 

1. For all of Locke’s responses to the problem which scepticism causes for indirect realism you need to know that Locke is a fallibilist. This means that he does not believe we can only have knowledge as the result of a certainty-producing-mental-process. He also points out, ‘merely having the idea of a thing in your mind no more prove its existence than the picture of a man is evidence of his existence in the world….’ (Remember Locke lived before photography.) Therefore, have no certain evidence of the existence of the mind-independent world if we are an indirect realist. However, for Locke, it is possible to know of the existence of the mind-independent world if we have evidence which is strongly suggestive. 

2. Locke argues, first, that our sense experience is involuntary, by which he means that we cannot choose our sense experience – either that we have it or what it be of. Of course, we can, to use an example, close our eyes, but this misses the point. Locke is claiming that sense experience which is “turned on” is involuntary. Not that we can never “turn off” our sense organs. If we have our eyes open and they are pointed in the direction of an unobstructed elephant, then we see it. Sense experiences, Locke claims, ‘force themselves on me’ so that ‘I can’t avoid having them’.  

3. Locke contrasts the involuntary nature of sense experience with the voluntary nature of other mental states. If I remember, or I imagine, then these can be voluntary – I can choose them.  

4. Locke argues that the involuntary nature of sense experience suggests that sense experience comes from outside of the mind – that a mind-independent world exists to cause my sense data. 

5. In response to the involuntary nature of experience, we could object that the existence of dreams suggests that sometimes a mental event can be involuntary and yet still mind-dependent. When I have a nightmare, for example, it is typically an involuntary event; if anything, I should love to stop the nightmare – not have it continue – but I can’t stop it. And yet, a nightmare is still a mind-dependent event; the awful creatures of my nightmares have no mind-independent existence. So, the distinction between voluntary and involuntary does not overlap entirely with the distinction between mind-dependent and mind-independent. 

6. In reply to this response Locke argues that dreaming can be very different to wakeful perception. It might be argued that sensations and dream experiences are distinguishable by the vividness (or impactfulness) of them. Locke suggests that if you were aware of a furnace and you wanted to check if your sense data where caused by a mind-independent furnace you might stick your hand in the furnace. If a real furnace existed, your sensation would feel very different from a dream experience of burning yourself in a furnace. The experience would be much more striking. 

7. But in dreams things seem more real than they are. There are lucid dreams afterall. These are dreams which are utterly convincing when you are in them. A classic example is the morning routine dream, where you dream you have woken up and conducted your morning routine.  

8. Ultimately, Locke never claims that he can provide a water-tight proof of the existence of a mind independent world. So, he would likely not be troubled by the possibility of lucid dreams, and fall back on the probability, as he estimates it, that the mind-independent world exists on the basis of the involuntary nature of the senses. 

The coherence of the senses  

1. Locke argues that there is a coherence of the senses. By coherence Locke means agreement. Locke is claiming that each of the senses might confirm the other about the primary qualities of any given supposed mind-independent object. He appears to be claiming that the different senses can produce alike sense data of primary qualities. Imagine that we were concerned to establish if a mind-independent cube was in front of us or not. We might look at the supposed mind-independent object and count its faces. Then we could feel the faces. Both by sight and touch we should reach the conclusion that we are aware of six face all equal in size and positioned just so, and therefore we are aware of a cube. The look of the faces is like the feel of the six faces. We must ask why the sense of sight and touch should agree like this, if there is no mind-independent object to explain their agreement. It would be a strange coincidence for the two senses to agree in the absence of a mind-independent object, which explained their agreement. (This is not a water-tight proof of the existence of a mind-independent world. There are other possible reasons why there would be coherence between the senses. However, remember that Locke does not see the need to provide a water-tight proof. He regards the coherence of the senses as very suggestive of the existence of a mind-independent world, instead.) 

2. Locke sometimes brought together the coherence of the senses and the involuntary nature of sense experience arguments. Michael Lacewing summarises an extended example, offered by Locke, which brings the two arguments together, as follows:   

3. ‘I know from experience that I can change how a piece of paper looks by writing on it. (This connects sight and proprioception – my sense of my hand moving.) I can plan what to write, and I know in advance what the paper will look like. But I cannot bring about the sense-data of seeing the paper with words on it just by imagination; I have to actually write. And once I have written something, I can’t change the words I see. This shows that sense-data aren’t ‘merely playthings of my imagination’. Finally, if someone else reads those words aloud, what I hear corresponds to what I intended to write. And this ‘leaves little reason for doubt’ that the words as written on the paper exist independent of my mind.’ 

4. In the writing example above, we have agreement of sight, proprioception and hearing. The agreement also appears to be involuntary. These two phenomena, considered together, Locke regards as highly suggestive of the existence of a mind-independent world.  

Response to Locke (1) Mass sense deception 

1. The coherence of the senses does not eliminate the possibility of mass sensory deception. Perhaps both touch and sight are both deceiving me about the existence of the external world in the same way. 

2. In reply to this response, Locke would no doubt argue that mass sense deception can be very different to wakeful perception. It might be argued that sense deceptions are distinguishable by the vividness (or impactfulness) of them. Locke suggests that if you were aware of a furnace and you wanted to check if your sense data where caused by a mind-independent furnace, you might stick your hand in the furnace. If a real furnace existed, your sensation would feel very different from a mass deception of burning yourself in a furnace. The experience would be much more striking. 

3. If this defence does not convince you, it is important to note that the problem which mass sense deception causes for indirect realism is not a problem which is unique to indirect realism. Other theories of perception would be caused similar problems by mass sense deception. Therefore, if the only outstanding problem with indirect realism is the problem of mass sense deception, it would be unfair to dismiss indirect realism for that reason alone. 

Response to Locke (2) Molyneux’s problem 

1. Molyneux’s problem is a philosophical question which was around at the time of Locke and which, though different to the discussion we are having here, nevertheless, impacts on it. 

2. William Molyneux, an Irish scientist and politician, sent John Locke this philosophical question in a letter. The problem runs as follows. Imagine a man who is born blind and has learnt how to tell the difference between a globe and a cube using his sense of touch. In so doing he has also learnt how to label each. He knows the object which produces the feel of six faces, twelve edges and eight vertices is the cube. In contrast, the object with one continuous face, no edges or vertices, is the sphere. Now let’s suppose this same man is cured of his blindness. Furthermore, on a table in front of him is place a similarly sized cube and sphere. Could this formally blind man, now tell the difference, by his restored sight alone, between the cube and the sphere? The question raised by Molyneux amounts to the following. Is any coherence between the senses something naturally given in sense experience, or is it something which has to be learnt? Or, to put it another way: are touch sense data, naturally alike, sight sense data, or does any likeness have to be learnt? 

3. Locke answered Molyneux’s problem by arguing that the formally blind man would have to learn the connection between his sense data given in touch and his sense data given in sight. This response from Locke appears to be the opposite one to which we might expect after learning of his claims about the coherence of the senses. Here in response to Molyneux, Locke seems to be saying there is not natural (given) coherence of the senses. Or, to put it another way: touch sense data are not naturally alike sight sense data. It seems Locke cannot hold both positions: the coherence of the senses and his response to Molyneux’s problem. He must choose one and give up the other. 

4. Berkeley, an idealist who you will shortly study, argues that Locke’s response Molyneux’s problem is correct – the senses do not cohere. Berkeley would claim there is no more natural (given) resemblance between the sight and the touch of a cube than there is between the colour of an apple and its taste, or the sound of a bell and its shape. If Berkeley is right then Locke ought to give up his argument from the coherence of the senses. 

Other responses to issue of scepticism (Cockburn and Russell)

Cockburn's response  

1. Last lesson we noted, with the help of Molyneux's problem, that it is debatable whether the sense data produced by different senses of the same object, are alike. It is not clear that the sight sense data of a cube are the same as the touch sense data of a cube. That being so, it is not clear that Locke's argument from the coherence of the senses is convincing.   

2. Catherine Totter Cockburn, a philosopher influenced by Locke, argued for a similar, though arguably improved line of argument.  

3. Instead of arguing that the sense data produced by different senses of the same object where alike, Cockburn argues that it is possible to form predictive inferences from one to the other.   

4. If, for example, in see a train arriving down the tracks I can form the predictive inference that the sound of the train clacking on the tracks will become loaders as I see the train become bigger. This is not a rare occurrence. I can multiple examples. As I see the fire engine depart, I hear the pitch in its siren change. As the siren approaches the pitch of the siren rises and as it departs it lowers. This is so predictable scientists can explain it in terms of a scientifically confirmed effect – the Doppler effect.  

5. If I see a fire and doubt whether it is real, I can confirm its reality by touching it. Another example of this kind was given by Catherine Trotter Cockburn in her ‘A letter from an anonymous writer to the author of The Minute Philosopher’. She notes that one and the same object causes perceptual experiences through different senses. The experiences themselves are very different, e.g. seeing an object and hearing the sound it makes. But we learn which visual experiences go with which auditory experiences, e.g. seeing a dog and hearing a dog’s bark. With the association made, we can accurately infer from one experience to the other; just from seeing a dog, we know what sound it will make. And if we experience a change in vision, e.g. a train moving from near to far, we can infer the change in sound, e.g. its horn becoming quieter. Why would we be able either to confirm our experiences using different sense, or be able to predict them, unless there is something which both senses perceive but that is independent of being perceived by any particular sense?  

Russell’s responses  

1. Bertrand Russell offers two responses to the issue of scepticism about the existence of the mind independent world.  

2. Firstly, Russell offers a response, which he ultimately does not find convincing, but which it is important to explore, nevertheless, to understand why it is a weak response.  

3. Russell rejects this argument because it assumes something that we can’t know: that there are other people, that they have sense-data, and that their sense-data is similar to mine. To assume that there are other people is to assume that there are physical objects, since people are physical objects. But the question was how, from my sense-data, do I know that there are physical objects? In answering that question, I can’t assume that there are physical objects (such as other people) – that’s begging the question! (To beg the question is a faulty form of argument: it is to assume what is to be proved).  

4. Russell offers a second argument for the existence of the mind-independent world. To understand this second argument, you need to know what a hypothesis is. A hypothesis is a proposal that needs to be confirmed or rejected by reasoning or experience. We treat as true those hypotheses which have a high predictive and explanatory power and yet are the simplest available. 

5. How does Russell make the claim in reason 3? He uses an example to illustrate. He asks you to imagine you have a cat and that the cat regularly goes out in the morning after feeding full, energetic, clean and dry. However, when the cat returns in the evening he is hungry, tired, a little dirty and wet. The regularity and predictability of these events is best explained, in Russell’s view, by the hypothesis that the mind-independent world does exist. 

Bringing the debates together 

1. We have discussed a number of ways in which an indirect realist might defend their position against scepticism. These defences, however, do resolve to a straightforward response. The existence of the mind-independent world it he best hypothesis, but is not known directly. It is supposed to be the best hypothesis for a variety of reasons.  

1. It explains the involuntary nature of sense experience.  

2. It explains the (supposed) coherence of the senses.  

3. It explains our ability to form predictive inferences from one sense about another.  

4. It can explain the coordination of action and perception (the piece of paper example). 

5. It has high explanatory and predictive power and simply explains the predictability and regularity of experience. 

2. However, a problem remains. Lacewing sums up the problem well.  

3. ‘If indirect realism is correct, then it seems the existence of physical objects remains a hypothesis, something we have to infer. We can argue that this is a significant weakness… It is very counterintuitive to think that perception doesn’t put us in direct touch with physical objects. But this is entailed by the claim that we have to infer the existence of physical objects.’ Let us put things this way. The Big Bang and evolution are hypothesises. When we compare our position in relation to these hypothesises and our position in relation to existence of the mind-independent world, they don’t seem obviously comparable. 

4. Philosophical direct realism can explain many of the issues which indirect realism raises against it, but does not require us to accept that the existence of the mind-independent world is a hypothesis. It could also be argued that direct realism is at least as simple as indirect realism.