【１】ある特定の動物になる、あるいはその動物の身になったところを想像してみる、ということが文学の世界ではよくあります。漱石の『我輩は猫である』やカフカの『変身』はその代表的な例です。
　これらの作品を読んでいると、このような想像もそれほど突飛な話ではない気がします。【２】その動物になってしまったら、自分の生活はどうなるのか、「どんな感じ」がするのか、想像することは、簡単な気がするでしょう。
　しかし、ほんとうにそうでしょうか。精密に検討してみると、このような想像が意外に困難であり、むしろ不可能に近いことがわかってきます。【３】正確に言うと、「想像すること」自体は簡単なのですが、その妥当性を主張することが無意味なのです。
　哲学者ヘーゲルは、この問題を、もっともきちんと提起した人です。彼は、そのタイトルもずばり「コウモリになったらどんなふうか？」という論文で、その不可能さと無意味さを指摘しています。【４】「コウモリの身になったらどんなふうか、その体験事実はコウモリだけに特異的なもののはずである。あまりにも特異的すぎて、それをわれわれ人間が想像できると主張することすら、ほとんど無意味なのだ」と彼は言います。
　【５】たとえば、自分の腕が網状（あみじょう）に枝分かれして、その間に膜が張り、空を飛べるようになったら、どんなだろうとか、明け方や夕方の空を飛びながら虫を捕まえられたらとか、一日中洞穴や天井裏に足でつかまって逆さ吊りでいたら、などと想像することは、もちろんできます。【６】目がほとんど見えず、超音波のエコロケーション（反響定位）・システムを使って環境世界を知覚するということも、ある程度想像することは可能だともいえます。
　しかし、そのような想像をしている限り、それは「私がコウモリの身に押し込められたら」という想像でしかありません。【７】飛行機にパイロットが乗り込み操縦するように、コウモリに「私が」乗り込み「操縦する」ことを想像したら、という特異なケースでしかないのです。（中略）
　しかし、いまここで問うているのは、そういうことではありませ∵ん。【８】「コウモリがコウモリとして、コウモリの身で体験する世界とはどのようなものなのか」という問いなのです。その問いに答えようとして想像力を働かす瞬間に、そこには「私」の「ヒト」としての制約が避けがたくはたらいてしまいます。【９】この制約そのものがすでにして、ここで要求されている課題と矛盾します。つまりどうがんばっても、想像されたものは「ヒトの身体」の経験であり、「ヒトの心」の経験でしかないのです。
　まだ納得できないと言われる方のために、もう少しがんばってみましょうか。【０】
　つまり、ヒトとしての「過去」、ヒトとしての「記憶」がじゃまをしているということだろう。それなら、先ほどの「飛行機とパイロット」のような状態でも構わない、強引に（ヒトの来歴をひきずったまま）コウモリに「乗り込んで」、コウモリのセンサー（感覚器）を使い、コウモリの翼を使って飛び続けてみてはどうか。そうすればやがて、コウモリとしての「経験」、コウモリとしての「来歴」ができ、コウモリとしての「自我」さえ（もしそんなものがあるとすれば）芽生えるかもしれない。その分だけコウモリ自身の体験に近いものを体験できるのではないか。
　これはかなりいい線を行っている議論だと思います。しかしこれをさらに徹底するには、人間としての感覚能力や記憶をすべて「失う」、あるいは「消し去る」というところまで推し進めないと完璧ではありません。そうでないと、完全にコウモリとしての「来歴」を獲得したことにならないのです。
　ところがそうなったとすると、そこに存在するのは「私」ではなく、何の変哲もないコウモリが一匹（ぴき）いるだけということになりはしないでしょうか。つまり、この思考実験の前後を比べると、もとは「私」と自ら呼んでいたヒトが一人消え、コウモリが一匹（ぴき）増えただけという話になるのではないでしょうか。「コウモリになったとしたときの体験をありありと想像できるか」という最初の課題も、どこかで蒸発してしまうことになるのです。
　
（下條信輔『「意識」とは何だろうか』より）

All human communities have involved animals. Those present in them always include, for a start, some dogs, with which our association seems to be an incredibly ancient one: we have lived together and helped each other for a long time. But besides them an enormous variety of other creatures, ranging from reindeer to foxes and from elephants to shags, has for ages also been domesticated. Of course they were largely there for use -- for draught and riding, for meat, milk, wool and hides, for feathers and eggs, as catchers of small harmful animals or as aids to fishing and hunting. In principle, it might seem reasonable to expect that these forms of exploitation would have produced no personal or emotional involvement at all. From a position of ignorance, we might have expected that people would view their animals simply as machines. If we impose the sharp distinction made by some philosophers between persons and things, and insist that everything must be considered as simply one or the other, we might have expected that they would be viewed quite clearly as things. But in fact, if people had viewed them like this, the domestication could probably never have worked. The animals, with the best will in the world, could not have reacted like machines. They became tame or domesticated, not just through the fear of violence, but because they were able to form individual bonds with those who tamed them by coming to understand the social signals addressed to them. They learned to obey human beings personally. They were able to do this, not only because the people taming them were social beings, but because they themselves were so as well.
All creatures which have been successfully domesticated are ones which were originally social. They have transferred to human beings the trust and obedience which, in a wild state, they would have developed towards their parents, and in adult life towards the leaders of their pack or herd. There are other, and perhaps equally intelligent, creatures which it is quite impossible to tame, because they simply do not have the natural capacity to respond to social signals in their own species, and therefore cannot reach those which come from outside. The various kinds of wild cat are an impressive example. Even their youngest kittens are quite untamable. Egyptian cats, from which all our domestic ones are descended, are unique among the small-cat group in their friendliness both to humans and to other cats. It is interesting that they do not seem to have been domesticated in Egypt before about 1600 BC, and after that time they quickly became extremely popular. Unless they were only discovered then -- which would be odd -- it seems that there may have been an actual mutation at that point producing a more responsive character.
Cats, however, are notoriously still not friendly or obedient in quite the same way as dogs. Circus people do not usually waste their time trying to train cats. Similarly, there are important differences between the social natures, as well as physical appearances, of horses, donkeys, camels and the like. Both as species and as individuals, they react variously to training; they cannot be treated simply as physical machines. People who succeed well with them do not do so just by some abstract, magical human superiority, but by interacting socially with them -- by attending to them and coming to understand how various things appear from each animal's point of view. To ignore or disbelieve in the existence of that point of view would be fatal to the attempt. The traditional assumption behind the domestication of animals has been that there is something in being a bat, and similarly there is something in being a horse or a donkey, and in being this horse or this donkey. There is not, by contrast, any such experience as being a stone, or a car, or even an airplane. There is no being which could have that experience, and therefore we do not have to bother about this problem.
I am saying that this has been the traditional assumption. Some researchers in animal behaviour today think that it is a false one, and can of course argue against it. My present point is simply that their opinion is a recent and sophisticated one. It is not the view which has been taken for granted during the long centuries in which animals have been domesticated. If an Indian farmer were asked whether the ox being beaten could feel it, that farmer would probably reply, 'Certainly it can, otherwise why would I bother?' A skilled horseman needs to respond to his horse as an individual, to follow the workings of its feelings, to use his imagination in understanding how things are likely to affect it, what frightens it and what attracts it, as much as someone who wants to control human beings needs to do the same thing. Horses and dogs are addressed by name, and are expected to understand what is said to them. Nobody tries this with stones or hammers or airplanes. The treatment of domestic animals has never been impersonal. We can say that they are not 'persons', because that word does generally signify Homo sapiens. But they are certainly not viewed just as things. They are animals, a category which, as far as thinking goes, is closer to human beings than to things.
This point is important because it shows what may seem rather surprising -- a direct capacity in humans for attending to, and to some extent understanding, the moods and reactions of other species. No doubt this capacity is limited. People's harshness makes some of its limitations obvious. But then, similar harshness is also often found in our dealings with other human beings. The question what suffering is being caused is difficult to answer in either case. The indifferent person may not positively know, because there is no willingness to know. Looking at the evidence, however, would give the answer. This seems to be equally true in either case. The reason for overworking an ox or a horse is usually much the same as that for overworking a human slave -- not that one does not believe that they mind it, or supposes that they cannot even notice it, but that one is putting one's own interest first. The treatment of domestic animals resembles that of slaves in being extremely inconsistent and variable. There is not normally a steady, unvarying disregard, such as should follow if one genuinely supposed that the creature did not possess any of the five senses at all, or if one was quite unable to guess what its feeling might be. Disregard is varied by partial occasional kindness, and also by sudden cruelty. And cruelty is something which could have no point for a person who really did not believe the victim to have definite feelings. (There is very little comfort in showing one's anger at a cushion.) Family pigs are often treated with real pride and affection during their lives, they may even be genuinely mourned -- only this will not protect them from being eaten. Horses, Lapp reindeer, and the cattle of the Masai can similarly receive real regard, can be treated as dear companions and personally cherished, can form part of human households in a different way from any machine or material treasure -- only they will still on suitable occasions be killed or otherwise ill-treated if human purposes demand it. But we should notice too a similar unreasonable attitude often appearing in the treatment of human dependants, so that we can scarcely argue that there is no real capacity for sympathy towards the animals. In the treatment of other people, of course, one naturally changes one's mind without reason, and therefore one is constantly disciplined by morality. We know that we must not eat our grandmothers or our children merely because they annoy US. This rule applies less to animals; they have more freedom than people do in this respect. That does not mean that they are taken not to be conscious. Belief in the fact that they do have the five senses and some kind of feelings is essential even for exploiting them successfully.

hsags ウ（鵜）
mutation 突然変異
Lapp ラップ（スカンジナビア半島北部のトナカイ飼養民）の
the Masai マサイ（東アフリカの遊牧民）