'We can call this primitivism. It is an attitude that is easy to criticize, to mock. It is deeply masculine, masculinist. Its ramifications into politics are to be mistrusted. But when all is said and done, there remains something attractive about it at an ethical level.

'It is also impractical, however. You do not feed four billion people through the efforts of matadors or deer hunters armed with bows and arrows. We have become too many. There is no time to respect and honour all the animals we need to feed ourselves. We need factories of death; we need factory animals. Chicago showed us the way; it was from the Chicago stockyards that the Nazis learned how to process bodies.

'But let me get back to Hughes. You say: Despite the primitivist trappings Hughes is a butcher, and what am I doing in his company?

'I would reply, writers teach us more than they are aware of. By bodying forth the jaguar, Hughes shows us that we too can embody animals – by the process called poetic invention that mingles breath and sense in a way that no one has explained and no one ever will. He shows us how to bring the living body into being within ourselves. When we read the jaguar poem, when we recollect it afterwards in tranquillity, we are for a brief while the jaguar. He ripples within us, he takes over our body, he is us.

'So far, so good. With what I have said thus far I don't think Hughes himself would disagree. It is much like the mixture of shamanism and spirit possession and archetype psychology that he himself espouses. In other words, a primitive experience (being face to face with an animal), a primitivist poem, and a primitivist theory of poetry to justify it.

'It is also the kind of poetry with which hunters and the people I call ecology-managers can feel comfortable. When Hughes the poet stands before the jaguar cage, he looks at an individual jaguar and is possessed by that individual jaguar life. It has to be that way. Jaguars in general, the subspecies jaguar, the idea of a jaguar, will fail to move him because we cannot experience abstractions. Nevertheless, the poem that Hughes writes is about the jaguar, about jaguarness embodied in this jaguar. Just as later on, when he writes his marvellous poems about salmon, they are about salmon as transitory occupants of the salmon life, the salmon biography. So despite the vividness and earthiness of the poetry, there remains something Platonic about it.

'In the ecological vision, the salmon and the river weeds and the water insects interact in a great, complex dance with the earth and the weather. The whole is greater than the sum of the parts. In the dance, each organism has a role: it is these multiple roles, rather than the particular beings who play them, that participate in the dance. As for actual role players, as long as they are self-renewing, as long as they keep coming forward, we need pay them no heed.

'I called this Platonic and I do so again. Our eye is on the creature itself, but our mind is on the system of interactions of which it is the earthly, material embodiment.

'The irony is a terrible one. An ecological philosophy that tells us to live side by side with other creatures justifies itself by appealing to an idea, an idea of a higher order than any living creature. An idea, finally – and this is the crushing twist to the irony – which no creature except man is capable of comprehending. Every living creature fights for its own, individual life, refuses, by fighting, to accede to the idea that the salmon or the gnat is of a lower order of importance than the idea of the salmon or the idea of the gnat. But when we see the salmon fighting for its life, we say, it is just programmed to fight; we say, with Aquinas, it is locked into natural slavery; we say, it lacks self-consciousness.

'Animals are not believers in ecology. Even the ethnobiologists do not make that claim. Even the ethnobiologists do not say that the ant sacrifices its life to perpetuate the species. What they say is subtly different: the ant dies and the function of its death is the perpetuation of the species. The species life is a force which acts through the individual but which the individual is incapable of understanding. In that sense the idea is innate, and the ant is run by the idea as a computer is run by a program.

'We, the managers of the ecology – I'm sorry to go on like this, I am getting way beyond your question, I'll be through in a moment – we managers understand the greater dance, therefore we can decide how many trout may be fished or how many jaguar may be trapped before the stability of the dance is upset. The only organism over which we do not claim this power of life and death is man. Why? Because man is different. Man understands the dance as the other dancers do not. Man is an intellectual being.'

While she speaks, his mind has been wandering. He has heard it before, this anti-ecologism of hers. Jaguar poems are all very well, he thinks, but you won't get a bunch of Australians standing around a sheep, listening to its silly baa, writing poems about it. Isn't that what is so suspect in the whole animals-rights business: that it has to ride on the back of pensive gorillas and sexy jaguars and huggable pandas because the real objects of its concern, chickens and pigs, to say nothing of white rats or prawns, are not newsworthy?

Now Elaine Marx, who did the introduction to yesterday's lecture, asks a question. 'In your lecture you argued that various criteria – Does this creature have reason? Does this creature have speech? – have been used in bad faith to justify distinctions that have no real basis, between Homo and other primates, for example, and thus to justify exploitation.

'Yet the very fact that you can be arguing against this reasoning, exposing its falsity, means that you put a certain faith in the power of reason, of true reason as opposed to false reason.

'Let me concretize my question by referring to the case of Lemuel Gulliver. In Gulliver's Travels Swift gives us a vision of a Utopia of reason, the land of the so-called Houyhnhnms, but it turns out to be a place where there is no home for Gulliver, who is the closest that Swift comes to a representation of us, his readers. But which of us would want to live in Houyhnhnm-land, with its rational vegetarianism and its rational government and its rational approach to love, marriage and death? Would even a horse want to live in such a perfectly regulated, totalitarian society? More pertinently for us, what is the track record of totally regulated societies? Is it not a fact that they either collapse or else turn militaristic?

'Specifically, my question is: Are you not expecting too much of humankind when you ask us to live without species exploitation, without cruelty? Is it not more human to accept our own humanity – even if it means embracing the carnivorous Yahoo within ourselves – than to end up like Gulliver, pining for a state he can never attain, and for good reason: it is not in his nature, which is a human nature?'

'An interesting question,' his mother replies. 'I find Swift an intriguing writer. For instance, his Modest Proposal. Whenever there is overwhelming agreement about how to read a book, I prick up my ears. On A Modest Proposal the consensus is that Swift does not mean what he says, or seems to say. He says, or seems to say, that Irish families could make a living by raising babies for the table of their English masters. But he can't mean that, we say, because we all know that it is atrocious to kill and eat human babies. Yet, come to think of it, we go on, the English are already in a sense killing human babies, by letting them starve. So, come to think of it, the English are already atrocious.

'That is the orthodox reading, more or less. But why, I ask myself, the vehemence with which it is stuffed down the throats of young readers? Thus shall you read Swift, their teachers say, thus and in no other way. If it is atrocious to kill and eat human babies, why is it not atrocious to kill and eat piglets? If you want Swift to be a dark ironist rather than a facile pamphleteer, you might examine the premises that make his fable so easy to digest.

'Let me now turn to Gulliver's Travels.

'On the one hand you have the Yahoos, who are associated with raw meat, the smell of excrement and what we used to call bestiality. On the other you have the Houyhnhnms, who are associated with grass, sweet smells and the rational ordering of the passions. In between you have Gulliver, who wants to be a Houyhnhnm but knows secretly that he is a Yahoo. All of that is perfectly clear. As with A Modest Proposal, the question is, what do we make of it?

'One observation. The horses expel Gulliver. Their ostensible reason is that he does not meet the standard of rationality. The real reason is that he does not look like a horse, but something else: a dressed-up Yahoo, in fact. So: the standard of reason that has been applied by carnivorous bipeds to justify a special status for themselves can equally be applied by herbivorous quadrupeds.

'The standard of reason. Gulliver's Travels seems to me to operate within the three-part Aristotelian division of gods, beasts and men. As long as one tries to fit the three actors into just two categories – which are the beasts, which are the men? – one can't make sense of the fable. Nor can the Houyhnhnms. The Houyhnhnms are gods of a kind, cold, Apollonian. The test they apply to Gulliver is: Is he a god or a beast? They feel it is the appropriate test. We, instinctively, don't.

'What has always puzzled me about Gulliver's Travels - and this is a perspective you might expect from an ex-colonial – is that Gulliver always travels alone. Gulliver goes on voyages of exploration to unknown lands, but he does not come ashore with an armed party, as happened in reality, and Swift's book says nothing about what would normally have come after Gulliver's pioneering efforts: follow-up expeditions, expeditions to colonize Lilliput or the island of the Houyhnhnms.

'The question I ask is: What if Gulliver and an armed expedition were to land, shoot a few Yahoos when they become threatening, and then shoot and eat a horse, for food? What would that do to Swift's somewhat too neat, somewhat too disembodied, somewhat too unhistorical fable? It would certainly give the Houyhnhnms a rude shock, making it clear that there is a third category besides gods and beasts, namely, man, of whom their ex-client Gulliver is one; furthermore, that if the horses stand for reason, then man stands for physical force.

'Taking over an island and slaughtering its inhabitants is, by the way, what Odysseus and his men did on Thrinacia, the island sacred to Apollo, an act for which they were mercilessly punished by the god. And that story, in turn, seems to call on older layers of belief, from a time when bulls were gods and killing and eating a god could call down a curse on you.