Michael G. F. Martin is something of a philosopher’s philosopher.1 More specifically, he is a philosopher of perception’s philosopher, as this is the area within which most of his very influential work falls. Martin is particularly well-known for motivating and defending ‘naïve realism’, the view that perception constitutively involves relations of awareness of the ordinary, mind-independent world around us. However common-sensical this thought is, philosophers over the ages have found it notoriously hard to hold on to. Various problems – the gap between the world as it appears in experience and how it is described in physics, the fact that things can appear differently to different persons, and (not least, as will be clear later) the possibility of hallucinations that completely match the real thing – have lead many to accept either a more traditional ‘sensationalist’ conception of experience, according to which experience is constituted by awareness of certain subjective, private items, or a slightly more modern ‘intentional’ or ‘representational’ conception, according to which experience only fallibly represents an external reality. Martin belongs to the minority group of philosophers who escape these options by embracing the currently much-debated position known as ‘disjunctivism’. According to this view, a given perceptual experience is either a genuine perception or a hallucination (or some other form of illusion), but the term ‘perceptual experience’ does not therefore denote a supposed fundamental kind of state common to all three of them. According to disjunctivism, there is no such fundamental common kind. Hence, perceptions – as opposed to other, even subjectively indistinguishable states – can coherently be construed as involving genuine relations to the environment, thus preserving the ‘naïve’ picture. There will be more of this below.
Filosofisk supplement are pleased to present this grey eminency of philosophy of perception to a more general audience – though (as the photo suggests) there isn’t much about him that is grey. His soft-spoken Oxford eloquence made the transcription from speech to written text an easy task (in fact, this transition was initiated during the interview itself, as the last bit was carried out in Skype’s chat mode, where the interviewer could also quickly ascertain that Martin is by far the fastest and most accurate typer he ever encountered). So while the questions Martin discusses are complex and difficult, the language in which he discusses them is simple and clear. This, as well as Martin’s occasional witticisms and crisp characterizations of philosophical opponents, should make the reader feel less intimidated by the difficulty of the terrain she is about to enter. The philosophy of perception is a thriving field at the moment, and this is a good opportunity to get to know it better. To this aim, we have also added some notes along the way, explaining the background for the discussion and providing references for works mentioned, as well as for further reading.
Getting into the topic
Why is perception philosophically important?
Well, for one thing, it is among our oldest topics. It goes back right to the beginning of Western philosophy. It already concerned the Presocratics. And it concerned Plato, in some of his most important dialogues. According to Michael Frede, it is Plato who first introduces a technical term for sense perception, when he lets the words aisthanesthai and aisthesis mean to perceive and perception respectively.2 One answer, then, is simply that perception is a very old topic. But this also suggests how bad philosophy is, for we have never managed to solve the problem of perception – we just keep coming back to it again and again.
Slightly less frivolously: Understanding perception is important to understand how we fit into the world that we encounter and reflect on. There are questions, distinctively philosophical questions, about the everyday, human-shaped world: What does it take for there to be a table or a chair there, can you eliminate it, and so on. Part of what philosophers have been concerned with, then, is the ordinary world and what it takes for it to be the way it is. There aren’t just philosophical questions about small things – atoms, fields, space-time points, and so on; there are also questions about the medium-sized things we find around us, just as we find them. And as part of the ordinary world, there is also the ordinary mind, the aspects of our mind which are part of our everyday lives. This is where the philosophy of perception comes in. There are aspects of our psychology which aren’t part of this ordinary picture, and so there is a science of that. I am interested in both psychology as a science and the philosophy of psychology. But I think of the problems of perception as belonging mainly within the philosophy of mind, which is concerned with just the aspects of our psychology which are part of our ordinary world.
The topic of perception also raises some questions about epistemology and metaphysics – questions about knowledge and skepticism on the one hand and questions about ontological categories like relations, events and states on the other. But this is not the main concern in the philosophy of perception, which is part of the general project of making sense of ourselves.
Many people come to perception from epistemology? Take a philosopher like John McDowell, who seems to have influenced you.
Well, but people normally come with bad epistemology – and then that makes for bad philosophy of perception. And I don’t know if McDowell really comes from epistemology. Anyway, there are aspects of his philosophy of perception which are really questionable, because he is only marginally interested in perception as such. He is trying to fit it into his big picture of the mind. And so some things he says – in particular some of the things he says about reasons – are really Procrustean: Things are being fit into crude categories that come from elsewhere.
But this is also a little unfair. McDowell was a major inspiration for me, as for many people in the Oxford environment I was brought up in. However, there were other central figures. I was among the graduates of the eighties; I arrived in 1981. The year before, both John Mackie and Gareth Evans had died. David Wiggins came back to Oxford after a couple of years, and he was an important influence. Another was Michael Dummett – who by the way was the supervisor of Carsten Hansen, though he never supervised me.3 Still others were Christopher Peacocke and John Foster. Foster was for a time my supervisor.
Really, the idealist?
I used to go to his lectures. I thought he was a sheer maniac, but I was also very impressed by him. Anyway, I never did that much work with Foster. My main undergraduate teacher and finally PhD supervisor was Paul Snowdon. I remember being really fascinated by perception as an undergraduate in my second or third year in one of his courses, writing a puzzled essay about the causal theory of perception. Paul would never say what he thought himself, so phenomenologically, it feels like an issue that really comes from me. But sociologically, it is of course no surprise that I got interested in this, since the teacher who was my real hero had written this really significant paper.4 He was a kind of cult figure in certain circles in Oxford: He didn’t publish much, but he was seen as formidably clever.
You are well-known for your defence of disjunctivism and ‘naïve realism’. But I think it is fair to our readers not to begin there. So let me begin by asking: How do initiate your students to the topic of perception?
I normally structure my teaching around the argument from illusion and the argument from hallucination. You can think of these as the two strategies that philosophers of perceptions have tried to use to say very general things about perception. So you can say I teach a rather traditional course, although it is an eccentric set of readings: I like to start out worrying about some things from G. E. Moore. Then I look at the works of Thompson Clarke and Frank Jackson – you don’t get two more different philosophers! – and raise some worries about the distinction people have wanted to draw between ‘direct’ and ‘indirect’ perception. I think people don’t understand the contrast that they want to draw with those words.5
Jackson has a very clear definition of ‘direct’ and ‘indirect’ – or, in his terms, ‘immediate’ and ‘mediate’ – seeing in his book Perception.6 But it is a definition that doesn’t work. And Clarke is very good at explaining why in ‘Seeing Surfaces and Seeing Objects’, which is much less well-known. It is brilliant, but a little crazy – it is mostly about seeing tomatoes and nibbling at cheese, which is why I sometimes call it ‘pizza philosophy’. Basically, what we can see from Clarke’s discussion is that Jackson misses some of the ways in which seeing is sensitive to our context.7
What I want all this to lead up to is the idea that the fundamental question we should ask in the philosophy of perception is this: What does it take for experience to be the way it is? I take it that the more traditional questions about the objects of experience hide this more basic question about the character of experience, its phenomenology. So sense-datum theories are in fact motivated to explain the character of experience, which is not how they are traditionally defined: They are usually defined in terms of the claim that we ‘directly’ perceive images or sense-data. So it takes some interpretive work to show that this question – whether we are aware of sense-data in this way – is in fact a question about what our experience is like. Sense-datum theory should rather be defined by saying that what constitutes my experience’s being the way it is, is my awareness of mental or at least non-physical sense-data with certain sensible qualities. As sense-datum theorists see it, my experience requires the presence of sense data, and its character would be different if the sense-data were different. It is through that idea that the notion of ‘immediate seeing’ is implicitly defined by Jackson. That is not how he puts it, but that is what we need to understand to make sense of the view.
And what is wrong with this way of understanding it?
Well, it is good if the view also claims that the relation you bear to the sense-data is one of seeing. But you could have a view which says: “No, no, it’s awareness, but it’s not strictly seeing, for seeing involves interacting with light and so on.” So such a view does not affirm that you see sense-data; it only says you’re somehow aware of them and that they characterize your experience. According to Jackson’s definition, then, such a view will not be a form of indirect realism. But this means that the question of ‘direct realism’ doesn’t get at what really matters. If, by contrast, our focus is on what determines the character of our experience – what it takes for our experience to be the way it is – then the question of whether we ‘see’ sense-data is not the interesting question.
Once you have got this far, the argument from illusion turns out to be hopeless.8 I try to make my students see why it is hopeless; I get it into premises and a conclusion and show why it doesn’t work as an argument. In fact, it’s puzzling to see it set out as an argument, since it is such a bad one: Why do people ever give it; as if the reasoning had any force? From this point, I gradually move towards the idea of the causal argument from hallucination, which is a much better argument. In fact, this argument constrains our choices among views of perception. It gives us a way of defining the logical options of views about perception.
When you speak of the causal argument from hallucination, and not just the argument from hallucination, you have in mind the argument that we can have the same proximal causes – the same stimulation of the retina, or even just the same goings-on in the brain – and thereby produce an experience which for the subject is just like the one she would have if she were really perceiving? And the conclusion is that disjunctivism is false.
Yes. What we should all agree on is that subjectively, things will be the same for the subject, in that she cannot distinguish her state from one of really perceiving the world. As I said, this argument constrains our views on perception. The argument purports to establish that disjunctivist views are false, and so that the character of our experience isn’t determined by the scene perceived.9
What the argument raises for us is two questions about experience, the answers to which – yes or no – give four options – or, as I will explain, actually only three. These options define the basic ways experience could be. And since you can combine the three options, we actually have seven basic positions all in all. Thus there are seven basic philosophical positions about perception, not three.
By contrast, what people often set up is this: You can be either an intentionalist, or sensationalist, or you can have a mixed view. They think those are the basic options. And more traditionally, people used to say that you are either a direct realist, an indirect realist, or a phenomenalist, so again, three options. But as I said, we actually have seven.
The first question is:
(1) Is the existence of what is presented to me constitutive of my experience’s being the way it is?
In other words, does the phenomenal character of my experience depend on the existence of what is presented to me – the object of awareness or what I will call ‘the presented element’?
The second question is the converse of the first:
(2) Is my experience’s being the way it is constitutive of the existence of what is presented to me?
In other words, is the presented element dependent on my experience?
The reason why we have three and not four options is that you cannot answer (1) negatively and (2) positively: You cannot have the phenomenal character constitutive of the presented element and the presented element possibly not existing.10 This gives us the following scheme, which defines sense-datum theory, intentionalism, and naïve realism:
Sense-datum theories – or, more generally, sensationalist theories – answer both questions in the positive: Since they accept that the argument from hallucination shows that we have the same kind of experience in both perception and hallucination, they must assume that the presented element is mind-dependent – a sense-datum or a sensational feature. Intentional theories answer both questions in the negative: We are indeed presented with mind-independent objects, but those objects are not required to exist for experience to be the way it is, as is again supposedly shown by the argument from hallucination. We perceptually represent that we are presented with a yellow orange, but this does not depend on there in fact being an orange there. But naïve realist theories reject the argument from hallucination and answers (1) in the positive and (2) in the negative: Experiences that are specifically perceptions do indeed require that the presented element exists. But that doesn’t mean that hallucinations also require the existence of some suitable entity – even if they result from the same neural activity that would under other circumstances produce genuine perceptions.
And why are there seven positions all in all?
The seven options are a matter of arithmetic. As I said, the two questions induce three options. That means that experiences can have sensational properties, intentional properties, or instantial properties, differentiated by the relative dependence or independence of the character of experience on its object and vice versa: Sensational properties require that the presented element exists but is mind-dependent; intentional properties don’t require that the presented element exists and hence can be mind-independent; instantial properties require that the presented element exists and is mind-independent. But experiences are normally complex, so they can have combinations of these properties; an experience could have all three kinds of property. And since no experience can lack all three, we have 23 – 1 = 7 positions: Pure sensationalism says that all experiences have only sensational properties; pure intentionalism says that all experiences have only intentional properties; what we might call pure worldliness says that all experiences have only instantial properties. Mixed views say that some experiences have sensational and intentional properties; or sensational and instantial properties; or intentional and instantial; or all three.11
And now we have a framework in which to understand the general positions in the philosophy of perception – a decision tree that gives you the basic options. For instance, naïve realism is best thought of as a view which is committed to there being instantial properties of experience. We typically suppose that we are aware of objects which exist independently of us, and that these characterize our experience. Naïve realism preserves this by accepting instantial properties. But presumably it is neutral on whether there are any sensational or intentional properties in addition; you don’t have to accept pure wordliness to be a naïve realist.
An excurse into sense-datum theory
Instantial properties as you have defined them are external, mind-independent properties. But sensational properties are also in a sense instantial, by the positive answer to (1)?
Well, just think of it in terms of the formal structure: Instantial properties are those properties that are defined by a positive answer to (1) and a negative answer to (2): The character of the experience requires that its corresponding presented element exists, and yet exists independently of your experience of it. On the decision tree, sense-datum properties are sensational properties, for these theories answer (2) positively as well – or rather modern sense-datum theories do. Traditional sense-datum theories (Moore, Russell, Broad, Price) all took sense-data to be mind-independent. Hence, they end up accepting a variation on naïve realism from the point of view of the decision tree.
A strange kind of naïve realism! Unless they were phenomenalists or neutral monists, these sense-datum theorists would have to assume a ‘double’ layer of mind-independent properties?
That was part of Austin’s original objection. Russell flipped back and forth across kinds of neutral monism. But Moore more or less held the view you indicated. Price ended up as a kind of phenomenalist. The key thing about all of them is that they posited a psychological law concerning objects of awareness: In order to have an experience with a certain character, we would have to be immediately aware of some item distinct from the ordinary objects around us.
But these theories also aren’t a viable option in response to the causal argument from hallucination. This is one of the elements of mess in the recent discussion because people don’t know their history properly. It was of essence for original sense-datum theorists that sense-data are independent of us; this was part of Moore’s refutation of idealism, and he always stuck with it. But as Austin pointed out, once you make that move you have no grounds for showing that we are always aware of non-physical sense-data. After WW2, philosophers who discussed sense-data tended to assume that if they existed, they were mind-dependent. This is no surprise really: Given a widespread commitment to causal exclusion in the physical world, non-physical and non-mental sense-data are a problem.
It seems that most people now think these sense-datum controversies are really irrelevant. As you said, perception is an old topic: How important is this history today?
Well, in general I think history of philosophy is important. But it is particularly important in the philosophy of perception, because so many people seem to rely on bad sets of assumptions – which have some history to them. A good thing to read on this, by the way, is Myles Burnyeat’s ‘Conflicting Appearances’.12
In a well-known article, Gilbert Harman says that sense-datum theorists simply missed the “elementary point” that perception is an intentional phenomenon.13 Is that failing to take history seriously?
Harman most definitely! Gil is proud of his disdain of history. Look, sense-datum theorists were not confused about judgement – they didn’t introduce ideas as the objects of thought. So they thought there was something special about perception. What they thought was special about perception leaves no trace in Harman’s discussion. So he hasn’t exactly made sense of the historical debate. And in turn he hasn’t got the full content of the issues for the debate he is engaged with. I have a couple of papers where I discuss some of these historical matters: ‘Beyond Dispute’ and ‘Sensible Appearances’ as well as a paper on Austin’s Sense and Sensibilia.14
So what can we learn from the history surrounding sense-datum theories?
Oh, on the whole only bad things! But the important thing I think they are symptomatic of is the idea that there is a fundamental difference between sensory awareness and mere thought. And that is an idea you get down the generations, down to thinkers such as Ned Block.15 It is a very interesting thought, but one which is difficult to articulate. And again, it is what leads to the two questions that define logical space. It lies behind what I have elsewhere labelled ‘actualism’ – namely, a positive answer to (1): Sensory awareness involves something having to be there.16 Now, given the causal argument from hallucination, actualism can be true of some aspect of experience only if the object of awareness is also dependent on our awareness of it. In other words, a positive answer to (1) entails a positive answer to (2), and that blocks naïve realism. Given the causal argument from hallucination, actualism requires mental items like sense-data or qualia. That has lead many to answer (1) in the negative. But the choice between sense-data and intentionalism is a derivative choice: It arises when you have already accepted the causal argument from hallucination.
The causal argument from hallucination can validly be reconstructed as a reductio of the hypothesis that there are instantial phenomenal properties in the sense defined above. If there are no instantial phenomenal properties, then experience either has sensational or intentional phenomenal properties, or both – these are the three options people standardly recognize. Sensational properties have one dimension in common with instantial properties (actualism); intentional properties another (mind-independence). That is what makes the argument from hallucination and the possibility of disjunctivism fundamental. If the causal argument can be blocked, then we need other reasons to suppose experience is either intentional or sensational.
This is something you have argued in several papers.17 But many people still think that disjunctivism isn’t really important: Why not accept intentionalism, which John Searle, for instance, says is also a form of direct or naïve realism?18 When experience is veridical, the represented properties are instantiated, and hence the character of experience is constituted by the scene perceived?
Well, first the term ‘naïve realism’ is just a term of art. So John can say what he likes. What is interesting is what he is committed to or not. I started using ‘naïve realism’ rather than ‘direct realism’ because, as I said, I don’t think people define the distinction between ‘direct’ and ‘indirect’ in any useful way. So everyone could say they were direct realists, or insist that we all had to be indirect realists, without there being any interesting dis-agreement among them. We should banish use of the term ‘direct’. I was thinking of taking a shotgun to talks and lectures and simply eliminate anyone slipping into using the term. The problem with intentionalism is that the character of experience does not really depend on the scene perceived. Since you could have the same experience even if you were merely hallucinating, the character of your experience is not constituted by the scene perceived. But it is an interesting question: Why should we believe that the object of awareness has to be there in sense perception? As I mentioned, the fact that many, many people have been moved by this thought is reflected in the different treatment of sensation and thought over the generations. The question concerns what the substance of the debate is. The core of the issue is what it takes for experience to be the way it is, as I stressed. But the debate around disjunctivism has tended to ignore this.
Before we leave this topic, I want to ask a question about your ‘negative’ or ‘epistemic’ conception of disjunctivism – which you hold is also forced upon us by the argument from hallucination. All parties agree that hallucinations and illusions are subjectively indistinguishable from perceptions, but according to your form of disjunctivism, that is really all we can say about them: Hallucinations are states that cannot be distinguished from perception merely by introspective reflection. Beyond that, there is no ‘positive’ characterization of their phenomenology.19 However, many philosophers, including some disjunctivists, have found this claim problematic: How can the states be merely impossible to distinguish – mustn’t there be some ‘positive’ properties of the experiences in virtue of which they are thus indistinguishable? And doesn’t the view make a mystery of the phenomenology of hallucination, which must certainly be constituted by something?
Is there a direct way of answering this question? What you are pressing really is at the fundamental point at which disjunctivism – and there are not really multiple forms of disjunctivism in any interesting sense; we are here concerned with the cluster of discussions generated by J.M. Hinton’s original paper and book – takes leave from the traditional debate.20 An awful lot of the secondary market discussion of these matters really fails to see where disjunctivists are coming from. They find it unbelievable, and so cannot enter into debate, only rudely state their disapproval.
What is going on when you introspect and reflect on what your sense experience is like? Are you bound to succeed in singling out some way an aspect of the world is which is independent of your inspection, but which nonetheless you have the skills to report on adequately? The assumption that you always can so succeed is what disjunctivists are really being skeptical about. If we think that when awake we are always conscious and that there is something it is like for us so to be conscious, and that we can be self-aware of how we then are, then there is a question how to conceive of consciousness and what it is like which avoids that strong assumption of success. That is what the ‘negative epistemic condition’ in the end amounts to: an account of what such self-awareness might be without making the strong assumption.
There is more to say – and I say some more of it in ‘On Being Alienated’ – but I realize that people found that all rather difficult to parse or to stomach.21 It will have to suffice for now, I think.
Methodology & psychology
Tyler Burge claims that the debate around disjunctivism is an example of an old-fashioned way of philosophizing. He says disjunctivism is simply refuted by science – and he is not one of those who think generally that philosophy should be replaced by science.
Tyler Burge can on occasion be unwittingly a bit pompous. I am not sure what it is to be fashionable, but perhaps Tyler Burge is. I guess I can see him in leathers on a motorcycle… Well, it has become fashionable to say in some vague way that disjunctivism is inconsistent with science. Since being fashionable or not is no guide to truth, this is not a genuine objection; precisely because it is fashionable it is also ill supported by argument. Are we just taking his immense authority on these matters, or are we trying to follow Reason – in the way he seems to care so much about? The real issue is what a refutation by science is and whether Burge has shown that one can accept what our best theorists are committed to only if one rejects disjunctivism. That doesn’t look like a question we can settle just by looking at what the scientists say – given that the scientists quite rightly don’t waste their time trying to confirm or refute philosophers’ theories of these things.
Burge focuses on what he calls the Proximality Principle. Roughly, the principle says that a given proximal stimulus will result in a given experiential state, regardless of the distal conditions which produced this stimulus, and thus regardless of whether the experience is perception or a hallucination. Is this principle simply something he has made up himself?
There are a number of problems with the Proximality Principle. To begin with, he gives it in a deterministic fashion, but all the laws we have in psychophysics are probabilistic. So it cannot be derived from psychophysics.
Okay, but it doesn’t really help if it is only probabilistic, does it?
No, you are right; you can reformulate the Proximality Principle as problematic probabilistically – but I think it does indicate we are no longer in the realm of science and methodology when we are looking at his arguments. The key thing turns on whether the notion of ‘perceptual state’ that is included in the definition of the Proximality Principle includes conscious experience or not: If it does, then the principle doesn’t derive from the current methods of cognitive neuroscience, since most perceptual psychologists don’t see themselves as giving a direct account of conscious awareness. The psychologists think we need to operationalize these naïve claims we make about conscious awareness or perception before we can formulate any testable hypotheses. Thus understood, I think the Proximality Principle should be rejected, without rejecting any decent science.
If the Proximality Principle is taken just to refer to perceptual states as cognitive neuroscience specifies them, then it is fine, but it doesn’t in itself issue in the relevant result. For the question then becomes whether, when we raise a question about conscious awareness, there can be a difference between two subjects which is not a difference in the states posited by cognitive neuroscience. And for all we have said the answer to that question may be yes.
Is your claim that the states they describe are only physiological or at least subpersonal states?
I am wary of using the personal/subpersonal distinction. I am also wary of legislating a priori about what neuroscientists can or cannot study. The claim is about what the current concerns of their investigations are. How you might think of it is rather like this: Suppose you had some Martian cognitive neuroscientists who lacked any conscious awareness of the world, but who ex hypothesi could still formulate scientific theories. Then maybe for them there would be no interesting difference between someone who could really see and had conscious visual awareness of the world and someone who just had perfect visual hallucinations: The two would match each other in physiological responses to the world, and the difference for us would make no difference to them. But for someone who is conscious, the difference between being conscious of something and merely seeming to be conscious of it is a big difference. And it is that conscious awareness we as philosophers are interested in. So we haven’t entirely tied it down by looking at what the Martian cognitive neuroscientists can study. Maybe the fashionable Tyler Burge is really a zombie Martian cognitive neuroscientist!
So consciousness is the special realm for philosophers?
I don’t quite see the need to say that. But yes, I am skeptical of a science of consciousness.
Well, that was deliberately tendentious on my part. But what about Reason: What is it we as philosophers find out, over and above what the scientists can tell us? Are we investigating conceptual truths, or some otherwise special, metaphysical truths, which we can know simply by reflection?
Well, I tend to find methodological questions a bit dry. I’m not quite sure what either of those is. Aren’t we just interested in whatever is the case, and we use to hand whatever methods we have got?
To return to him once more, Burge thinks the philosophical arguments for disjunctivism are like Hegel’s deduction of the number of the planets.22
Well, when mr. Burge booms his great authority in the cognitive sciences he typically gets it wrong. He proposes deterministic principles where the sciences lack them, and besides the claims he makes about constancy are contentious even from a neuroscientific perspective. There are lots of different things that philosophers do, and they approach these questions in different ways. The most obvious thing that holds these matters together are the history and sociology of philosophy departments in universities.
Only we philosophers can sit and talk about the psyche without ever doing a psychological experiment. Can we be certain that we’re onto something?
Well, maybe and maybe not. Like any other human intellectual endeavour, you can have your doubts. There are good days and bad days. I’m not sure there is something special about philosophy here – except that, well, philosophy is very hard. Philosophers like to boast to other academics that they are good at argument. But on the whole philosophers are rubbish at argument – really, really bad. Arguments are difficult. And when it comes to psychology – well, if there is something that they are worse at than argument it is doing psychology. How many philosophers do you know who are good at statistics? Let alone experimental methods.
The mind as we find it is like the world around us that we find: The tables and chairs, the earth and the sun. There are questions about these which are not the same as the scientific questions about structure and order and origin. And these are among the questions philosophers ask and have always asked. So the scientific study of mind will replace these questions only if science asks the only questions to be asked. We should not be ignorant of science – that would be stupid. But that is not to say that our questions are exhausted by science. They should be informed by it, but to work out how they should be informed is a difficult thing. And most philosophical responses to recent empirical work are nugatory. Philosophers should know as much about psychology as they can know. But it is difficult for researchers in the senses to know all that is going on, let alone untrained philosophers keeping up with it too – and let alone working out how this additional material bears on the questions the philosophers were first asking. But on the whole I wish philosophers had a better sense of what psychologists were up to.
I suspect that to many you will sound like a strange mix of an English 1950-style ordinary language philosopher and a modern “must be informed by science” guy.
Well, that’s fine. Philosophers have a bad sense of their own methods, and a bad inclination to follow the herd.
The content view
In finishing, let me turn to a recently fashionable debate – the debate about the so-called ‘content view’. What is this view?
You need to ask the people who defend it surely. Ask Susanna Siegel, Alex Byrne, Susanna Schellenberg – all have written papers claiming to defend the content view. But they each define it differently.
At least we know what ‘content’ means when we talk about propositional attitudes. We know what it is for a thought to have content.
Not necessarily. Even in propositional attitudes talk of content can mean different things. And there are disputes over what propositions are, and whether all beliefs or desires are attitudes towards whole propositions. But at least with those states we are at home with the notions.
You yourself used to write that experience ‘represents to us’ such-and-such – at least back in 1994…
Sure. Remember that being a naïve realist is not incompatible with accepting the existence of either sense-data or intentional aspects of experience. One could think that there are intentional aspects to some experiences but that experiences are also in part relations to objects in the world around us.
So why accept intentional properties if you are naïve?
Well, why not? Go back to the decision tree that gives the options. The question then is: What would show that some aspect of experience is intentional? There are other problems with the content view however. One problem is the equivocation over the term ‘content’; it means different things in different writers. But there is also assimilation of sense experience to propositional attitudes. That is related to the point I made earlier about a driving motivation when sense-datum theorists and others accept actualism. But that is at a tangent to whether any aspect of experience is representational or intentional.
Okay, I agree about that. But I misstated my question a bit. What I wanted to ask is: Why should a disjunctivist think of awareness of ‘wordly’ objects and properties in terms of representation of them? There are forms of representation which aren’t ‘intentional’ in the sense of allowing for non-existence or non-instantiation: The state of knowing is ‘instantial’ according to your scheme, since it is factive; so are ‘object-dependent’ attitudes.23 McDowell and Snowdon seem to think of perception in just such terms. McDowell currently defends the content view against Charles Travis and other disjunctivists who reject it.
There are, I think, a couple of issues here. First, suppose we take the nature of sense experience to involve genuine relations to objects and their properties: Couldn’t the obtaining of such relations still somehow depend on or be explained by sense experience possessing a propositional or inten-tional content? For all I have said, the answer to this question might be positive. But what it would turn on is some story of how possessing intentional properties should realize and determine features of what our sense experience is like. So one needs a story of how intentionality and phenomenology fit together. Absent such a story, the speculation would be a bit like this: Might not ordinary objects really be composed of minute particles of Gruyère cheese which operate in such a way that they manifest the qualities we perceive?
Another issue concerns what one wants intentional content to explain and how it comes into the picture in the first place. Within the analytic tradition, propositional contents first surface in the debate through two different routes: First, D. M. Armstrong’s belief analysis of perception which sought to abolish all talk of sensory experience and awareness; second, the tradition influenced through Wittgenstein which liked to talk of ‘seeing as’ and the role of concepts in perception. Most of the recent literature seems at least implicitly influenced by Armstrong.24 So the idea is that we can specify what it is for sense experience to have an intentional content entirely independently of saying anything about what sense experience is like and then add an additional claim: That having such and such a content determines what sense experience is like.
I guess I find that strategy really unsatisfactory: I want to know what kind of determination or explanatory relation there would be between an experience’s having a certain content and its having a certain phenomenal character. I don’t think it helps just to be given some weak or strong supervenience thesis. The relevant determination claims here piggy back on some idea of explanation – as does in general constitution claims: So we really need to see how ascription of content to a perceptual state could explain other things about it.
That there is this demand has been obscured, I think, by the fact that there is – together with a confusion over the meaning of the metaphor of content – a different long-standing tradition on the basis of which content gets to bear on sense experience: the phenomenological tradition. In some of Husserl’s later lectures and in Sartre we have the idea of ‘presence in absence’ and so the idea that an object’s being given to the mind might be distinctively intentional. In most of my writings – but I haven’t made this anywhere near explicit enough – I have charitably assumed that intentionalists are assuming something like this. That is, they assume that there is some distinctive aspect of phenomenology which requires us to think of the state as intentional. With this as background, the clash, at the level of the taxonomy, between instantial and intentional phenomenal properties concerns the way in which we explain experience being that way.
Now I would grant that there are some other issues being raised by McDowell when he worries about the conceptual form of sense experience, and that those aren’t really addressed by our discussion. But at the same time, I think McDowell doesn’t face up to the worry above – how ascribing content to experience says anything about its phenomenological character. So I am neutral about Travis’s arguments against the content view as such; that debate turns on Travis’s general views about representation, which run very deep. In particular, I’m inclined to think that intentionalists can and ought to avail themselves of notions of representation which are not propositional or sentence-like.
A final question: When will your long-awaited book, Uncovering Appearances, well, appear?
A good question – and one I don’t have a definitive answer to. Presumably not more than 6 months after it is finished. And it is close to being finished.
Professor Martin, best of luck finishing the book, and thank you very much for the interview!
 This interview was originally published in Filosofisk supplement Vol. 9, No. 3 (2013).
 See Frede, M. (1987) ‘Observations on Perception in Plato’s later dialogues’, in his Essays in Ancient Philosophy (Minneapolis: University of Minnesota Press).
 Carsten Hansen is a professor of philosophy at the University of Oslo – and the interviewer’s former MA supervisor.
 Snowdon, P. (1981) ‘Perception, Vision, and Causation’ Proceedings of the Aristotelian Society, New Series, Vol. 81, pp. 175–92.
 Philosophers like Moore often start out worrying about whether we can really see such familiar things as oranges ‘directly’. For, they say, things would be just as they are visually even if only the skin of the orange where there in front of you, and hence you’re not strictly speaking aware of the orange, but only of its skin. And now you can repeat this line of argument: Even if the skin of the orange weren’t there, but only its outermost surface, you would still be aware of the same thing. What this shows, according to the argument, is that we are never ‘directly’ aware of ordinary items such as oranges, but only of something much less familiar – ‘mere surfaces’ or what C. D. Broad called ‘expanses’. Our awareness of ordinary things, by contrast, can only be ‘indirect’. Martin gives a lucid introduction to these issues in his (2005) ‘Perception’, in F. Jackson and M. Smith (eds.) The Oxford Handbook of Contemporary Philosophy (Oxford: Oxford University Press), pp. 701–38.
 Jackson, F. (1977) Perception: A Representative Theory (Cambridge: Cambridge University Press). The definition Martin refers to is given in Ch. 1, pp. 19–20. Roughly, Jackson defines ‘mediately seeing X’ as ‘seeing X in virtue of seeing something else Y’, and then ‘immediately seeing X’ as ‘seeing X not in virtue of seeing something else Y’.
 Clarke, T. (1965) ‘Seeing Surfaces and Seeing Objects’, in M. Black (ed.) Philosophy in America (London: George Allen and Unwin), pp. 98–114. According to Clarke, the context will determine whether you see the tomato or just a part of it, just as it can determine whether you nibble at a whole cheese or just the part of it affected by your nibbling. The fact that you see the tomato ‘in virtue of’ seeing its surface or that you nibble at the cheese ‘in virtue of’ nibbling a part of it doesn’t show that you see or nibble ‘indirectly’. Clarke thus provides the materials for undermining Jackson’s position – well before Jackson’s work came out.
 The argument from illusion comes in various forms, but in its basic form, it says that in cases of illusion, we must be aware of something which has the properties we are aware of in the experience. For instance, if a straight stick immersed in water seems to be bent, then I am aware of something which is in fact bent. And if we are aware of things different from ordinary objects in illusion, it is reasonable to suppose that these are the kind of things we are always aware of. Like the argument set out in note 5, then, the argument from illusion purports to establish that we are only ‘indirectly’ aware of the ordinary objects around us, that is, only in virtue of a more ‘direct’ awareness of mental or at least non-physical items – ‘sense-data’, in Moore’s term.
 Martin discusses the argument from hallucination in various articles. See in particular his (2004) ‘The Limits of Self-Awareness’, Philosophical Studies, Vol. 120, Nos. 1–3, pp. 37–89 and (forth) Uncovering Appearances (unpublished, partly available here), Ch. 3. The latter work in particular covers many of the issues discussed in the interview in much more detail.
 One might raise the worry here that the experience’s being constitutively sufficient for the existence of the presented element might not entail mind-dependence (the interviewer raised this worry after the interview). For instance, it is part and parcel of naïve realism that perception cannot occur in the absence of the presented element. Hence, perception guarantees that the presented element exists. To allay this worry (as Martin explained it), one must note that (2) is understood as asking whether the experience is wholly constitutive of the presented element, and hence whether the existence of the presented element depends on the existence of the experience (though we don’t have to understand (1) that way; the issue there is whether the presented element is at least partly constitutive of the experience). If the experience were not wholly constitutive of the object of awareness, then the occurrence of the experience would not be sufficient to explain its existence (even if it guaranteed it), and one would then face a problem in setting out the causal argument from hallucination: One would have to explain why the causally sufficient conditions for bringing about the experience should be able to ensure the obtaining of all of the conditions necessary for the experience to occur.
 Much recent debate in the philosophy of perception has concerned mixed views of the first sort, that is, the question of whether perceptions are purely intentional or involve additional sensational properties (sense data or qualia). For important statements of these ‘mixed’ and ‘pure’ forms of intentionalism respectively, see Peacocke, C. 1983 Sense and Content, Ch. 1 (Oxford:Oxford University press), and Harman, G. (1990) ‘The Intrinsic Quality of Experience’, Philosophical Perspectives, Vol. 4: Action Theory and Philosophy of Mind, pp. 31–52. Somewhat confusingly to the uninitiated, ‘pure’ intentionalism (or representationalism) is often simply referred to as intentionalism (representationalism) full stop.
 Burnyeat, M. (1979) ‘Conflicting Appearances’, Proceedings of the British Academy, Vol. 65, pp. 69–111.
 Martin, M. G. F. (2000) ‘Beyond Dispute: Sense-Data, Intentionality, and the Mind–Body Problem’, in T. Crane and S. Patterson (eds.) The History of the Mind-Body Problem (London: Routledge); (2003) ‘Sensible Appearances’, in T. Baldwin (ed.) The Cambridge History of Philosophy: 1870–1945 (Cambridge: Cambridge University Press); (2007) ‘Austin: Sense and Sensibilia Revisited’, unpublished. All three articles are available online here.
 In this perspective, the discussion of ‘mental paint’ is a descendant of earlier discussions of sensationalism. For a recent paper, see Block, N. (2010) ‘Attention and Mental Paint’, Philosophical Issues, Vol. 20: Philosophy of Mind, pp. 23–63.
 See Martin, M. G. F. (2000) ‘Beyond Dispute: Sense-Data, Intentionality, and the Mind–Body Problem’ (see note 14 above) as well as his (forth) Uncovering Appearances (see note 9), in particular, Ch. 1, pp. 32–3 and Ch. 3, pp. 8–14.
 Searle sets out his views on perception in his (1983) Intentionality: An Essay in the Philosophy of Mind (Cambridge: Cambridge University Press), Ch. 2; see in particular pp. 45–6 and 57–8.
 What even disjunctivists must accept in the argument from hallucination, Martin argues, is that the kind of mental state present in a hallucination will also be present in a genuine perception, given the same neural bases. What the disjunctivist denies, of course, is that this common kind is the most specific kind that the perception falls under; the existence of a kind in common between the states is consistent with the existence of more basic kinds that only one of them falls under. Yet this commonality severely constrains our positive characterization of hallucination: Suppose, for instance, that the disjunctivist tried to hold that phenomenology of hallucination were constituted by sensational properties. Since the same neural processes would also be present in genuine perception, perception would also have the same sensational properties. But since the disjunctivist also holds that the phenomenology of perception is constituted by the properties of the objects perceived, we have a problematic kind of overdetermination, seemingly leaving the instantial properties explanatorily redundant. This is the ‘screening-off problem’, to which Martin responds by denying that there is such any characterization to be given for hallucinations. All we can say about the kind of state occurring in hallucination is that its instances are indistinguishable from perceptions; we cannot know merely by reflecting on the state we are in that it isn’t a perception (this much is of course in common between hallucination and perception, since everything is indistinguishable from itself). What we cannot allow is a ‘substantive’ commonality consisting in, say, awareness of sense-data. Martin provides a much fuller discussion of this in his (2004) ‘The Limits of Self-Awareness’ (see note 9 above) and his (2006) ‘On Being Alienated’, in T. Gendler and J. Hawthorne (eds.) Perceptual Experience (Oxford: Oxford University Press), pp. 354–410.
 Hinton, J. M. (1967) ‘Visual Experiences’, Mind, New Series, Vol. 76, No. 302, pp. 217–227; (1973) Experiences (Oxford: Clarendon Press).
 See Burge, T. (2005) ‘Disjunctivism and Perceptual Psychology’, Philosophical Topics, Vol. 33, No. 1, pp. 1–78, p. 29: “It is fairly unusual, at least since the days of Descartes and Newton, for philosophical views to be as directly at odds with scientific knowledge as disjunctivism is. Hegel’s claim that there are seven planets springs to mind.” (In fairness to Hegel, it should be noted that the popular legend – that he gave an a priori ‘proof’ that there are seven planets just before Neptune was discovered – seems to be a mere myth. See Beaumont, B. (1954) ‘Hegel and the Seven Planets’, Mind, New Series, Vol. 63, No. 250, pp. 246–8; Craig, E. and Hoskin, M. (1992) ‘Hegel and the Seven Planets’, Journal for the History of Astronomy, Vol. 23, pp. 208–10.)
 Another point is that sense-datum theorists, with whom naïve realists share the commitment to actualism, did not think of awareness of sense data in terms of representation, but rather as a primitive relation (often called ‘acquaintance’). Now, naïve realists agree with intentionalists when it comes to the objects of perception. But does this in itself also mean that they must also depart from the sense-datum theorists’ construal of awareness?
 Armstrong sets out his view most famously in his (1968) A Materialist Theory of the Mind (London: Routledge and Kegan Paul), Ch. 10. For Wittgenstein’s discussion of ‘seeing as’, see his (1953/2001) Philosophical Investigations (Oxford: Blackwell), Part II, Sect. xi.