nostrilsSmell is the most elusive of the senses. Sight is beautifully structured and amenable to analysis in terms of consistent geometry and a coherent domain of colours. Smells… how does one smell relate to another? There just seems to be an infinite number of smells, all one of a kind. We can be completely surprised by an unprecedented smell which is like nothing we ever experienced before, in a way we can’t possibly be surprised by a new colour (with some minor possible exceptions). Our olfactory system effortlessly assigns new unique smell experiences to substances that never existed until human beings synthesised them.

There don’t even seem to be any words for smells: or at least, the only way we can talk about them is by referring to “the smell of X”, as in a “smoky smell” or “the smell of lemons”. We don’t have to do that to describe shapes or colours: they can be described as “blue”, or “square” without our having to say they are “sky-coloured” or “the shape of a box”. (Except perhaps in the case of orange? Is “orange” short for ‘the colour of oranges’?) Even for taste we have words like “bitter” and “sweet”. The only one I can think of for smells is “nidorous’, which is pretty obscure – and in order to explain it I have to fall back on saying it describes the “smell of” burning/cooking meat. All we have to describe smells is “strong” and “faint” (my daughter, reading over my shoulder, says what about “pungent”? She does not consider “pungent” to be merely a synonym of “strong” – you may be indifferent to a strong smell, but not to a pungent one, she claims).

With that by way of preamble, let me introduce the interesting question considered here by William Lycan: does smell represent? When we smell, do we smell something? There is a range of possible answers. We might say that when I smell, I smell sausages (for example). Or that I smell a smell (which happens to be the smell of sausages). Or I might say I just have a smell experience: I may know that it’s associated with sausage smells and hence with sausages, but in itself it’s just an experience.

Lycan (who believes that we smell a gaseous miasma) notes two arguments for something like the last position – that smell doesn’t represent anything. First, introspection tells us nothing about what a smell represents. If I were a member of a culture that did not make sausages or eat meat, and had never experienced them, my first nose-full of sausage odour would convey nothing to me beyond itself. It’s different for sight: we inherently see things, and when we see our first sausage there can be no doubt we are seeing a thing, even if we do not yet know much about its nature: it would be absurd to maintain we were merely having a visual experience.

The second argument is that smells can’t really be wrong: there are no smell illusions. If a car is sprayed with “new car” perfume to make us think that it is fresh off the production line, we may make a mistake about that inference, but our nose was not wrong about the smell, which was real. But representations can always be wrong, so if we can’t be wrong, there is no representation.

Lycan is unimpressed by introspective evidence: the mere fact that philosophers disagree about what it tells us is enough, he feels, to discredit it. The second argument fails because it assumes that if smells represent, they must represent their causes: but they might just represent something in the air. On getting a whiff of my first sausage I would not know what it was, but I might well be moved to say “What’s that appetising (or disgusting) smell?”  I wouldn’t simply say “Golly, I am undergoing a novel olfactory experience for some opaque reason.”  I think in fact we could go further there and argue that I might well say “What’s that I can smell?” – but that doesn’t suit Lycan’s preferred position. (My daughter intervenes to say “What about ‘acrid’?”)

Lycan summarises a range of arguments (One is an argument by Richardson that smell is phenomenologically “exteroceptive”, inherently about things out there: Lycan endorses this view, but surely relying on phenomenology is smuggling back in the introspection he was so scathing about when the other side invoked it?). His own main argument rests on the view that how something smells is something over and above all the other facts about it. The premise here is very like that in the famous thought experiment of Mary the colour scientist, though Lycan is not drawing the same conclusions at all. He claims instead that:

I can know the complex of osphresiological fact without knowing how the rose smells because knowing is knowing-under-a-representation… that solution entails that olfactory experience involves representation.

That does make some sense, I feel (What about “osphresiological”! we’re really working on the vocabulary today, aren’t we?). You may be asking yourself, however, whether this is a question that needs a single answer. Couldn’t we say, yes sometimes smells represent miasmas, but they can also represent sausages; or indeed they can represent nothing.

Lycan, in what I take to be a development of his view, is receptive to the idea of layering: that in fact smells can represent not just a cloud of stuff in the air, but also the thing from which they emanated. That being so I am not completely clear why we should give primacy to the miasma. Two contrary cases suggest themselves. First, suppose there is a odour so faint I don’t even perceive it as such consciously, but have a misty sense of salsiccian (alright, I made it up) presence which makes me begin to think about how agreeable a nice Cumberland sausage for lunch might be. Wouldn’t we say that in some sense the smell represented sausages to me: but we can’t say it represented a miasma because no such thing ever entered my mind?

Second, if we accept layering we might say that the key point is about the essential or the minimal case: we can smell without that smell representing a sausage, but what’s the least it can represent and still be a smell? Can it represent nothing? Suppose I dream and have an odd, unrecognisable experience. Later on, when awake, I encounter a Thai curd sausage for the first time and find that the experience I had was in fact an olfactory one, the smell of this particular kind of comestible. My dream experience cannot possibly have represented a sausage, a miasma, a smell, or anything but itself because I didn’t know what it was: but, it turns out, it was the smell of curd sausage.

I think your reaction to that is likely to depend on whether you think an experience could be a smell experience without being recognisable as such; if not, you may be inclined to agree with Lycan, who would probably reiterate his view that smells are sensing-under-a-representation. That view entails that there is an ineffability about smell, and Lycan suggests this might help account for the poverty of smell vocabulary that I noted above. Interestingly it turns out that this very point has been attacked by Majid and Burenhult, albeit not in a way that Lycan considers fatal to his case. Majid and Burenhult studied the Jahai, a nomadic hunter-gatherer tribe on the Malaysian peninsula, and found that they have a very rich lexicon of odour terms, such as a word for “the smell of petrol, smoke and bat droppings” (what, all of them?). It’s just us English speakers, it seems, who are stuck with acrid nidors.


  1. 1. Hunt says:

    I suspect that “what it is like to smell like a dog” is probably as intricate a question as “what it is like to echolocate like a bat,” seeing that (no pun intended…yes it was) their olfactory epithelium is over ten times as large and hundreds of times more populated with sensory neurons, making their smell perhaps thousands of times more sensitive. Does that mean their smell is only broader and more sensitive, or can they construct maps and landscapes purely from the whiff of certain scents? Who knows.

  2. 2. Hunt says:

    And maybe that’s a partial answer to some of the issues raised here. We humans are vision-centrists, since that seems to be our dominant sense. Even the way we describe things often betrays this. If we were actually able to use smell to form an image of the sausage perhaps like a bloodhound–but there I go again! The “image”. Maybe we have to admit that the blunt instrument we know as our nose is not up to the task of rooting out (pun not intended…) how smell can represent things in the world.

  3. 3. Vicente says:


    it would be absurd to maintain we were merely having a visual experience

    would it be possible that you were dreaming about it for the first time?

    What is the difference with hearing? that two ears allow 3D processing of sounds?

    What when we watch a movie? are we really seeing the objects on the screen? and if we are in an augmented reality scenario?

    This representational issue looks like the old debate between empiricism and rationalism…

    The point is that we have neurons that interact with the world, in the retina or on the skin, or in the nose, and whose action potentials are triggered by a physical or chemical stimulus, photons, or pressure on the skin or the hearing sense, or molecules that induce smells or hives itch, so what?

    The interesting point is that when processed by different brain areas these signals raise a phenomenal experience build with qualia. What’s special about smell?

    The question is that a particular brain activity correlates with a phenomenal experience, and to this respect, all senses are the same. Even more, we can ignore the senses. Any stage before the signals are running along the nerves is irrelevant for the analysis. The sensorial information is not representational ‘per se’, it is the ulterior processing that produces representational results.

    So why the visual cortex produces a visual experience and the olphatory one a smell? are just the corresponding histological and anatomical architectures that makes the difference? is it how these signals are processed? is it something in the neurons?

    What about synesthesia?

    From a zoological perspective there are many things to be said about senses and their evolutionary appearance, being smell the first one, the one that is processed very fast with a very important emotional impact, etc etc, but to what consciousness concerns, one sense or another makes little difference…

    Can we have a representation of the world just using the smell sense? well, an amoeba has it, a representation of the amoeba world, even multidimensional if it can properly process chemical concentration gradients in a 3D space. What is it like to be an amoeba?

  4. 4. Cervantes says:

    I cannot agree with a lot of this. There are plenty of adjectives for categories of smells that don’t refer to a specific odorant: acrid, sweet, cloying, putrid, many more.

    We often attribute smells to otherwise unobserved objects and events, such as specific foodstuffs, dead animals, excrement, and so on. This means we have a representational interpretation of many odors.

    Could we have a representation of the world just using the smell sense? Well, it’s much more important for some quite intelligent critters than it is for us — dogs, as one obvious example. Clearly dogs explore and interpret their world through olfaction at least as much as through sight. They are undoubtedly a lot better than we are at attributing odors to definable causes, but we do it, and yes, we have names for odors.

  5. 6. john davey says:

    I think it’s a mistake, a common one, to think that there is a ‘coherent’ or even remotely geometric array of colours. The causes of colours – wavelengths of EM radiation- have geometry but not the effects which are the colours themselves. EM radiation has no colour of course, as colours are mental only.

    Colours are as arbitrary, imprecise and intangible as any smell. “Turquoise” may represent a composite of certain primary colours as a cause, but as an effect, as a sense datum, turquoise is as “different” from blue as any other colour, in the sense that there is absolutely no confusing them. We don’t mistake turquoise for blue.

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