In: Animal Rationality
Anselm Oelze
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According to a long-standing philosophical tradition, we humans are rational animals. This means that we are endowed with certain cognitive powers, namely, intellect and reason, that enable us to engage in various cognitive operations, such as concept formation, judging, or reasoning. It is these operations that shape the way in which we perceive and interact with the world. We conceptualise the brown furry thing we see as a dog, we judge that the dog is hungry when it desperately stares at the feeding bowl, and we reason that we should feed it if we want its hunger to disappear. To some extent, these cognitive operations even put us in a position to build our own worlds like, for instance, the world of logic or the world of science. In these worlds, dogs are not simply our pets or companions but they become the objects of our research. We might study their biology, physiology, and psychology and perhaps find out that dogs are just as smart and intelligent beings as we are. This finding would definitely change the way in which we treat dogs. We would begin to give them all the rights we grant to human beings and dog lead producers might finally become redundant.

As we all know, we have not yet reached this point and maybe never will. Still, many people would say that we are much closer to reaching it than our ancestors ever were. Since the advent of modern biology, psychology, ethology, and similar disciplines we have left the above-mentioned tradition behind. In its original form, or so the usual story goes, this tradition is rooted in the thought of Aristotle because it was Aristotle who claimed that only human animals possess rational souls or souls with rational faculties like intellect and reason. The denial of intellectual faculties to other animals was fateful, according to several scholars because it “produced a crisis in psychology, in ethics, and in religion,” as Richard Sorabji famously put it. 1 It produced a crisis in the sense that nonhuman animals were henceforth trapped in the sphere of arationality, that is, in a sphere significantly inferior to the sphere in which our own species resides. It took more than two thousand years for this crisis to come to an end. Of course, we still put leads on dogs, keep chimpanzees in zoos, and eat cattle. Nonetheless, we have begun to understand that the Aristotelian definition of the boundary between human and nonhuman animals needs to be revised. And once this has happened, the crisis will be over.

Now one might object that there never was such a crisis in the history of Western philosophy. For not only was Aristotle one of the most important and impressive philosophers of all times, but he also was one of the most prolific writers in what can count as the precursors of modern biology, psychology, and ethology. His treatises on the physiology and psychology of animals, both human and nonhuman, consist of several thousand pages and so he seems to be above suspicion in this regard since his picture of the animal realm is far from being one-dimensional. Be that as it may, one can hardly deny that there are many passages in Aristotle’s writings in which he clearly rejects the attribution of intellectual powers to nonhuman animals. 2 It would be naïve to think that these passages did not have an influence on those thinkers who came after him. The crucial question, however, is: what did this influence amount to? Was Aristotle really the beginning of a one-way road? Did his denial of reason to nonhuman animals lead everyone after him into the same direction? Was everyone hit by the crisis?

If one looks at the history of the animal/human boundary, one easily sees that there certainly was more than just one definition of this boundary, even following Aristotle. Ironically, it was Richard Sorabji himself who, in his seminal study of the history of the Western debate, has shown that already in Antiquity there was a whole spectrum of positions concerning the cognitive capacities of animals. Cats, bees, apes, or elephants were not taken to be dumb and unintelligent by everyone. There were also many who pointed to the astonishing abilities they have, many of which they share with us. 3 However, this spectrum seems to have disappeared by the beginning of the medieval period at the latest because, according to Sorabji, the (Western) Middle Ages were dominated by a “Christian tradition which selected just one side from a much more wide-ranging Greek debate.” 4 Thus, even if Aristotle’s views had produced less severe a crisis than originally thought, the beginning of the medieval period marked the beginning of a “dark age” for nonhuman animals. 5 And if we still have to deal with the consequences of that crisis some say it is because of “the gulf that millennia of Judeo-Christian indoctrination have dug between us and other animals.” 6

Claims like these certainly gain some plausibility from the fact that medieval Christian thinkers amalgamated the Aristotelian definition of the animal/human boundary with two particular biblical doctrines found in Gen 1:26-28. The first of these doctrines is the idea of humans being created ‘in the image of God’. By and large, this was interpreted to mean that humans are the only earthly creatures with a rational and immortal soul. Because of this rational soul they are cognitively superior to other terrestrial creatures. Closely linked to this cognitive superiority is humanity’s moral predominance. The doctrine of the ‘imago-Dei’ was thus accompanied by the idea of what is called the ‘dominium terrae’, humans’ dominion over the earth, including all living beings. 7 Because of this exceptional position of humans, the chasm between us and other animals was certainly deepened. As far as the discussion of animal cognition was concerned, “[a]ny real study of animal psychology would have to wait until after the end of the Middle Ages,” as Joyce E. Salisbury put it. 8 But is this actually true? Is it true that the Middle Ages were the height of the crisis diagnosed by Sorabji?

On the one hand, this picture is not entirely incorrect. For most, if not all, medieval authors subscribed to the premise that only human animals are rational animals in the sense that only they possess rational souls or the faculties of intellect and reason. Furthermore, medieval thinkers did not devote the same amount of attention to the discussion of nonhuman animals’ cognitive capacities as to other fields or disciplines from logic and metaphysics to Christology. But, on the other hand, it would be equally wrong to think that they did not care about this at all. In fact, they had a keen interest in finding out what separates humans from other animals, and they did not hesitate to ask whether the cognitive capacities we have are so much different from the capacities of other animals. They wondered what kind of cognitive processes underlie the behaviour of dogs, cats, bees, sheep, monkeys, ants, and many others, and they asked how such processes compare to those underlying our own behaviour. Are they entirely distinct or are they similar? Or are they even equal, perhaps? And how can we find this out if all we can do is observe other animals’ behaviour?

As the present study aims to show, not one but many answers were given to these questions. The spectrum of medieval views on the cognitive capacities of nonhuman animals was much more varied and disparate than one might think from hearing the story of the crisis. And so the denial of intellect and reason was not a one-way road. It led in different directions and, in particular, to the development of what can be called theories of animal rationality. This might seem like a plain contradiction in terms. If there really was so much support for the view that only humans are endowed with intellect and reason, it seems odd, if not wrong, to say that medieval thinkers developed something like theories of (nonhuman) animal rationality. But the point is that there was not much of a debate about whether nonhuman animals have cognition. It was relatively uncontroversial that almost all animals share a certain number of external and internal senses, such as sight and hearing or imagination and memory. What was at issue was rather the kind of cognition they have and whether their cognition is entirely non-rational. Although one might think that this question was taboo in the Middle Ages, the present book shows that it was not. Despite all of the differences between the present and the medieval debate on animal rationality, there are also many astonishing parallels. This is something one is likely to miss when hearing the story about the fateful crisis produced by Aristotle.


Sorabji (1993a), 1. See also Sorabji (1993b), 7f., and Steiner (2008), 17f.


See, for instance, De anima II.3, 414b18-19 and 415a7-8; De partibus animalium 641b7f.; Politica 1332b3-5. For a complete list of the loci classici see Sorabji (1993b), 12, n. 30.


Sorabji (1993b). Besides Sorabji’s study there are also valuable works on ancient views of animal cognition by Dierauer (1977); Cassin & Labarrière (1997); Steiner (2005), esp. 38–111; Gilhus (2006); Osborne (2007); Newmyer (2011); Harden (2013); Li Causi & Pomelli (2015).


Preece (2002), 62–90.


For a brief overview of these doctrines see Baranzke (2002), 82–88. For a critical discussion of the history of their reception see Cohen (1992).

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