Environmental philosophyreason means that animals cannot enter into reciprocal agreements or dis-
charge moral obligations, so they cannot be the subject of moral rights or
obligations. Singer acknowledges that animals are unable to comprehend
therequirements of acting as moral agents, but points out that the same is
true of various groups of human moral patients, such as those with learn-
ing difficulties, the senile or infants, who can neither reason nor talk – yet
their interests are still protected. Singer argues that the implicit grounds
on which such moral patients receive moral consideration is due to their
capacity to suffer (i.e. sentience). Logically we should therefore extend equal
consideration to the suffering of other sentient creatures, such as factory-
farmed livestock. Indeed, Singer ( 1979 :ch. 3) condemns as ‘speciesists’ those
who would treat the suffering of humans as more important than the suf-
fering of other species.
Other criticisms focus on the internal consistency of the arguments.
In particular, should all sentient creatures receiveequal treatment?Equal-
ity across species might suggest that rats, cats and humans should all be
accorded equal treatment, but few humans would be happy with the idea
that a drowning cat, let alone a rat, might be pulled from a pond before
a human. In practice, Singer says that all sentient creatures should receive
equal consideration, but that does not imply that they should receive equal
treatment. As a utilitarian, Singer is concerned with the total or aggregate
consequences in each particular situation. He argues, perhaps a little conve-
niently, that the capacity for human suffering is generally of a higher order
than for other creatures (Singer 1979 : 52–3). For example, the human capac-
ity to anticipate oncoming death, perhaps through a terminal illness, often
makes our suffering much greater. In particular, human capacities such
as self-awareness, intelligence and planning for the future make human
life more valuable than that of creatures not possessing those capacities.^14
Singer anticipates that human suffering will therefore receive greater weight
in the utilitarian calculus. On a straight choice, a human life will, almost
always, outweigh that of an animal. Indeed, it may be legitimate to use
mice in medical experiments if the outcome is to relieve suffering for even
asmallgroup of humans.
This line of argument suggests a weakness in Singer’s claim that all sen-
tient creatures have an interest. By attributing greater weight to capacities
such as self-awareness and planning, one inference is that Singer shows that
humans have interests whilst other sentient creatures simply feel pain. It
suggests that a stronger definition, by which ‘having an interest’ involves
plans, projects and purposes, is more valid. Creatures lacking those capaci-
ties are, arguably, creatures without interests. Applying this definition would
rein back attempts to extend value to a wide range of species, but it would
not necessarily confine it solely to humans. Certainly apes have some of
these superior capacities,^15 whilst other sentient creatures, such as mice,
may not possess such capacities – and therefore do not have interests
(see Box2.6). Of course, it does not necessarily follow that humans can treat