a) It should be useful, therefore, to consider the ways in which we do attempt to talk about sensing -

i) We speak of sensing as an `activity' of individual people - in `sausage-machine' terms, as an operation of the machine - though it is plainly not a deliberate physical activity in the way that bricklaying is, nor yet is it a `mental activity' in quite the way that believing is. It is `something we do' in the course of doing other things (like identifying) in a rather more clearly `doing' way.

ii) We speak of the senses as distinguishable parts, or functions, of the `machine' itself. Certainly we must have senses in order to do the sensing - yet it is difficult to decide whether we `have' them like we have hands and feet or `have' them like we have talents and moods. It is tempting to say that our senses are `the tools for doing the job'; yet, when we look at obvious analogues, like carpentry for instance where the tools are hammers and saws and drills and such, the parallel does not seem to hold. Having a particular sense is being able to sense in an appropriate way in a way that having a hammer is not necessarily being able to drive nails. So we do seem to be speaking of functions of the `machine' rather than of parts of it. Perhaps most significant feature of `senses' is its plurality. Sensing is just that performance [think back to identity]; to speak of senses implies that there are various different types of sensing - which, of course, there are.

iii) We speak also of sensible qualities and, in so doing, make a further sub-division. Not only is seeing quite different from hearing (though they both are, or include, instances of sensing); blue is quite different from red (although both are instances of the use of the same, visual, sense). But a quality must be the quality of something and have, thereby, some kind of external-world status. So to talk of sensible qualities is to attribute to the external reality (as `belonging' to it) certain aspects of our own sensory experience - or, perhaps more properly, certain characteristics which cause us to have that experience in the way that we have it. Though we always talk as if the quality were somehow `embedded in'the object: we say simply `This pen is blue'; we do not generally say `This pen presents to me in a way that makes me have an experience of blueness'.

It may be valuable to pause a moment here and ponder the idea that, to the extent that we are talking of our phenomenal world, we are right to say `the pen is blue'; to the extent that we are talking of the objective, `causal-to-phenomena' reality, the second locution would be more correct, since the blue in question can only be, for each of us, the unique experience he or she calls `blue'.In fact, in terms of `causal-to-phenomenal' reality, the correct locution would be `This presents to me in a way which makes me perceive a blue pen' since the pen-ness, like the blueness, is essentially phenomenal - but this will be taken up more fully in the next chapter.

b. There are other terms which should be considered. We speak of sentience, the characteristic of beings which sense, in a way that embraces the whole operation of becoming aware of the sensible qualities of objects. Indeed, to say that X is a sentient being is simply to assert that X has a capacity for consciousness. But, since consciousness must be of the world out there, and we assume that there are many sentient beings, we can find ourselves, in the light of the distinctions made so far, postulating a three-way distinction -

i) My own (or Jones's own) phenomenal world - wholly `composed of' experience per-se -

ii) The (common) phenomenal world about which Jones and I are communicating when one tells the other that this pen is blue - and

iii) The postulated causal-to-phenomenal reality which accounts for the effective equivalence of my phenomenal world and Jones's and, thereby, `creates' the phenomenal world for both of us.

No to the extent that -

i) We cannot but think of the world we are personally familiar with as the world we share with other people - complete with all `its' colours, sounds, textures and smells - yet, in doing so, we still demand also a totally objective reality against which our judgements are ultimately measured.

ii) Even at the `sense-stuff-level' we are guided by consensus. It makes perfectly good sense to say `I thought it was blue, but I am persuaded by my friends that it is really green'.

Thus references to sense-data can only be to the sensory aspects of our own phenomenal worlds taken as emanating from (i.e. conditioned by) aspects of the objective reality we are (thereby) aware of. On these terms, it is perhaps permissable to say that each of us `constructs' external reality from his or her sense-data. But, insofar as it is sensory, we are `giving it' to the world; the world is not 'giving it' to us (except to the extent that we ourselves, the centres of experience, are part of objective reality - thoughts are actual thoughts).

3. Now let us look more closely at sensing - the `activity' - and consider in just what way it is `something we do' -

a. We can, surely, allow that any `centre of experience' must be a centre of sensory experience. To be conscious is to be sensing, not just to be sensing. When we say that somebody returned to consciousness, we mean precisely that he once more became sensorily aware of his surroundings. Here it is instructive to consider the difference between dreaming and day-dreaming. Both involve the contemplation of situations other than the situations which actually pertain. But, in the one case, these are taken as pertaining (for the duration of the dream) precisely because we are not conscious - i.e. we are not responding sensorily to our actual surroundings; in the other case they are not taken as pertaining, precisely because their so doing would be incompatible with the actual reality with which we are sensorily appraised. Some people (those for which these are gradual processes) may find it useful to think of the experience of falling asleep and waking up. The sense-kinds seem to go out of, or come into, operation one-at-a-time - so that there is a kind of brief half-world in which the visual part is still (or already) a dream but the tactile part is `reality' (or any other such combination).

[Hallucination also involves some kind of division into awareness of reality in some sense modes and detachment from reality in others - but this is more complex and will be considered in the next paper].

b. One thing which should be quite clear is that sensing is totally involuntary; we can choose to look or to listen, but we cannot choose to see or to hear. How we sense is simply how we find ourselves sensing. If this were not so, there could be no intelligible distinction between sensing and imagination- imaging - and so no criterion of actual reality.

There is, therefore, a by no means trivial sense in which sensing is no more what we do than it is what is done to us by our environment. The environment cannot make a blind man see - but it can make a sighted man see blue and not red.

Nor can we decide not to sense at all (how nice it would be, sometimes, if we could!). We can hold our noses, stop our ears or shut our eyes and, thereby, exercise some control over what external objects impinge upon us sensorily - but we still smell whatever odour is in our noses, hear the thumping of our own blood circulations or see our own eyelids (so long as there is sufficient light). To tell someone with a severe pain simply to ignore it is not only callous, it is demanding the impossible.

[Here people's minds will probably turn to fire-walkers and such oddities. It cannot be denied that there is something strange here to be explained - but if fire-walking were simply a matter of `switching off one's own senses' then fire-walkers would get very badly burned feet - which they don't. A more common situation is that where, in the excitement of a battle (or a rugby match) somebody just does not notice getting a wound which, after the event, is very obvious. But such people do not decide in advance not to notice it - or they very surely would notice it.]

c. Although it is a slightly uncomfortable term it is hard to avoid describing sensing as intuitive - in the same way as logic must be intuitive - simply because we cannot explain it in terms of anything else, we must simply assume it (as it is) in any explanation. Sensing is, as it were, the primitive experience from which all further experience arises.

The point has been made that, since thinking is somebody thinking something about something, the `machine', the `centre of experience', must have two capacities - to sense and to reason. The one provides the something to think about and the other the capacity to think something about it. [Think of this in terms of the inter-relations of possibilities and necessities]. We should not, however, say glibly that sensing is simply intuitive and pass on to the next question - since,if we were pressed to explain intuitiveness, we may well find ourselves obliged to say something like `the kind of basic awareness typified by sense-experience'. So perhaps it is better to say cruder-sounding things like: The only way to know sensing is to do it - we are speaking of the experience itself. There is simply no way that colour could be explained to a congenitally blind man or sound to a congenitally deaf man even though they could learn to use colour-words and sound-words in appropriate contexts.

d. Here we should consider the well-know dictum: There can be nothing in the mind which was not previously in the senses. Whereas this is a (potentially misleading) over-simplification (it assumes both that minds are entities which can contain things and that sensing is, itself, a cognitive process), the basic point that it makes is nevertheless sound - we are not born with a range of concepts, only with capacities to form concepts. The capacity for logic (for recognising necessities as necessities) enables us to order our thinking about reality when we have `made contact with it'; the capacity to sense provides that contact. The concepts are of perceived and classified `structures' (customary complexes), but the content structured must be sensory content. If we think of perceiving as reasoning - which plainly it is; to perceive is to infer that a particular situation pertains - then there must be something to reason about (or from). If we did not sense, we could not perceive; experience per-se is basically sensory experience.

When we turn to experience as of the external world - i.e. to consideration of the experienced - it is necessary to make distinctions between perceiving, predicting, recalling, imagining and so on. [In the next paper we shall examine these more closely]. But, plainly, the initial awareness is in perceiving (we cannot recall what we have never known) and, equally plainly, that perceiving is dependent upon sensing.

[Here think again of the verifiability criterion of intelligibility - ultimately every concept must be `cashable' in sensory terms].

e. It is fairly obvious that we cannot perceive without sensing. It is less obvious, but equally necessary, that we cannot sense without perceiving.

Here compare: You can't have symbols without communication nor communication without symbols. One is the achievement and the other is the mode of achieving. If there is no achieving, then there can be no mode of achieving. The sensing/perceiving relationship is clearly parallel - but with one very important difference: if the communication attempt fails, there is no symbol (because nothing is functioning as a symbol) but there is still the symbol-token; if there is no perception, then there just isn't anything at all which could be described (analogously) as the sense-token - there are no sensations waiting to be sensed.

Again we must remind ourselves that thinking is somebody thinking something about something; all thought is propositional. Quite clearly, whatever sensing provides, it is not propositions - from which it follows that sensing per-se cannot be thought. This, of course, does not imply that it is not `within the thought realm' (as distinct from the `reality realm' and the `communication realm') - very plainly it is. Any attempt to characterise sensing as merely a physical performance which (in some mysterious way) `gives rise to' a mental performance runs quite counter to all our notions of sensing. We are talking of (some part or aspect of) experience, not of the mechanical causes of that experience. Here try to imagine a perfectly good pair of eyes hung up on a fence-post pointing at the cows in the field. Even if those eyes do all the things that eyes normally do, there can be nothing going on that we would call sensing - simply because no `centre of experience' is doing the sensing. We don't want to say 'There is sensing going but nobody is aware of it'!

For there to be thought (awareness, recognition) two things are necessary -

i) an intake of data - manifested as sensory experience - and

ii) `making something of' that data in `customary complex' terms - i.e. identifying, predicting, believing.

Thus sensing and perceiving are inter-dependent. Sensing is not, as has sometimes been suggested, the basic cognitive performance; in itself it is not a cognitive performance at all. But it is a vital ingredient of the basic cognitive performance, perceiving, and as such is known (we perceive that we are sensing) within that perceptual performance - and only within that perceptual performance.

Quite simply: sensing (as such) is the mode of perceiving - and the various modes of sensing manifest as the various modes of perceiving: seeing, hearing, smelling, etc.

4. Since we are treating sensing as the contact between the objective reality we perceive and the phenomenal world(s) which are the `product' of that perception and, thereby, represent for us that objective reality, the sensing itself must provide variety as a basis for `displaying the structures'. We should look now, therefore, at the different senses.

a. With the (real) sausage-machine, we have to push in the meat, bread, etc. for the machine to work on. With `our machines' we might be said to `draw in' the external reality data to work on - and we can think of the senses as doing the collecting. With this rather crude model, we can think of each separate sense drawing in or collecting its own kind of data. Put very simply: we don't hear colours or see noises.

b. it is wise, however, to avoid thinking of the senses as a neatly distinguished, finite collection. Most people would list five senses - visual, auditory, gustatory (tasting), olfactory (smelling) and tactile. But then there is some discomfort about kinaesthetic sense, our direct awareness of our own bodily states and movements; is this a sense in its own right or just an `internal operation' of tactile sense? It seems highly likely that the five-way division arises from our (learned) association of particular sense-experiences with particular bodily organs. We learn early in our lives to associate seeing with eyes, hearing with ears, tasting with pallets, smelling with noses - and tend to put everything else into a general rag-bag we call tactile. But consider:

i) Taste and smell are far more alike than, say, hot/cold is like hard/soft (generally lumped together as tactile).

ii) There are good grounds for supposing that other creatures - bats, bees, pidgeons... - have senses which we do not have. We obviously cannot know what it would be like having these other senses, how the direct experience would be, because we don't have them. But we do know what kind of experience it would be (like seeing and hearing in the same way as they are like each other). The notion of additional senses is quite intelligible.

iii) Indeed, it is possible to discuss intelligibly whether people do or do not have certain specific senses; there has, for instance, been argument about whether motion is directly sensed. It is also conceivable that some people have senses that the vast majority of people do not. Just think, if you were the only person who could see, how hopeless attempts would be to tell other people what it was that you could do and they couldn't.

iv) Here it is interesting to consider what people call extra-sensory-perception. `Extra' is used in two different ways. If people are using it as in `extra-mural studies' (other than, different from) then plainly `extra-sensory-perception' is a nonsense, a contradiction in terms, since perception just is the `processing' of sensory intake (so E.S.P. would be like an unmarried husband). But if `extra' is used as in `an extra addition of the paper' (an additional one of the same kind), then it is perfectly intelligible; it is simply perception in a sense mode over and above those most of us are familiar with (like being a husband through a different convention of marriage).

It is better, then, to think of sensing simply as that kind of experience - and allow that anything which is, or would be that kind of experience is, or would be, sensing.

c. Certainly this presents difficulties since it is seemingly not possible to say what kind of experience; we just (let us hope) know. Each sense-kind is unique; as `content', visual sense is utterly different from auditory sense - so when we say that seeing is like hearing, it is not immediately clear in what respects they are alike. We can only say `in their function' - remember the blind man and the deaf man who both perceived the arrival of the train. Plainly we do all have (effectively equivalent) concepts of sensoriness and, for all of us, the different sense-modes (or sense-kinds) are all instances of sensoriness. X is the same as Y in respect of Z. If X is visual sense and Y Is auditory sense, the best we can do to characterise the Z is probably as the unique uniqueness common to both -and/or as the data-presenting function in the perceptual process.

Think of a chap who was born blind but gains sight in early adulthood. This would provide a totally new and different experience for him - yet he would realise immediately that it was the same kind of experience as the hearing and smelling and feeling he was already familiar with. And note that, once we have a concept of sensoriness (however difficult it may be to describe), abstracted from the range of sense experiences we have had, we can postulate other (additional) senses (instances of sensoriness) in just the same way as, having gained a concept of catness from the cats we have encountered, we can postulate other cats (other instances of catness). From this it follows that we can assume that, if there are thinking creatures on other planets, they will have senses - without assuming that their senses will be the same, wholly or even partly (in actual sense-experience terms), as our own.

d. It is natural that we associate (in a causal explanation way) particular senses with particular organs. But these are merely discovered causal connections (think back to the reading of signs); the organ is not the sense. It is important to be quite clear that it is conceivable (thinkable and therefore possible) for the sense to exist (the experience to occur) without that organ or, indeed, without any organ. However strange it might be, we do know what it would be like to see without having any eyes; it is, for instance, not hard to imagine dreaming of this situation and, in the dream, being puzzled about how you were seeing. There is no logical connection between the concepts of using eyes and of seeing - or of any other organ/sensing relationship. Sensing is the experience itself. So, since we have allowed that this experience is in fact a set of unique subclasses (different senses), we should examine just what it is that is given in each of them - what (in traditional language) are the `proper objects' of the various senses. This is not so obvious as it may seem - consider: