Can animals suffer? Defending the animal suffering hypothesis on functionalist grounds.

This essay was written in late-2017 during my MA degree. Please note that I STRONGLY OBJECT to functionalism as an ontological account of mental states – see my PhD thesis for more info in this (pending; see ‘Against Functionalism’ in the meantime).

1. Introduction

Empirically testing for mental states such as pain states in animals is notoriously inconclusive, requiring one to make an inference to plausiblity according to available evidence (Shea & Heyes, 2010, pp.95-96). In the past, two identity theories of mind have been used for this inference; analytical behaviourism and psychophysical type-type identity theory. The former of these puts forward that mental states are behavioural dispositions, and the latter identifies mental states as physical states (Grush, 2002, pp.2-3) (Van-Gullick, 2009, p.3). One such proponent of type-identity theory is Bob Bermond, who argues that on the basis of neuroanatomical differences between the brains of humans and most non-human animals (hereafter, ‘animals’), we can reasonably conclude that they do not experience mental states – both of suffering, and of other kinds.

In §2 of this paper I shall present and address two arguments that are made in Bermond’s paper; that the behavioural research methods we use to infer mental states in animals are faulty or inconclusive, and that the similarities in physical systems between animals and humans are insufficient to ascribe mental states to animals. In §3 I shall present an early version of Hilary Putnam’s functionalist theory of mind – by which mental states are identified as their functional roles – as a more plausible alternative to Bermond’s ‘brain state’ approach. I shall also investigate contemporary methods of this functional inference, with respect to relevant evidence on the minds of animals. §4 shall conclude with a light commentary on the findings within this paper.

2. The ‘Myth’ of Animal Suffering

Before we discuss the issue of animal suffering any further, it is useful to clarify what the word ‘suffering’ entails (and to prevent possible future conflation of the term). Suffering is the phenomenal experience of one or more negative emotions (including pain, which is itself a negative emotion – see Bermond, 2003, p.79). Other elements said to be a part of suffering include the nociceptive registration of noxious stimuli and subsequent reflex, and the self-conscious recognition and realisation of harm that one has already experienced (Droege & Braithwaite, 2014, p.80). Although it is possible for these elements be a part of suffering, I do not think that they are necessary – but sufficient – conditions, since the former does not imply any point of view or ‘experience’ with which we can take into moral consideration, and the latter relies on there already having been an experience to begin with. “The question regarding suffering in animals, therefore, primarily addresses the issue of whether animals have a consciousness” (insofar as phenomenal experiences are conscious experiences., Bermond, 2003, p.79).

In ‘The Myth of Animal Suffering’, Bermond rejects the following two claims of support for the animal suffering hypothesis;

  • That we can assume animal suffering on the basis of an animal’s behaviour (ie; suffering-type behaviour indicates the presence of suffering-type mental states.
  • That animal suffering can be inferred due to “similarity between the structure of the sensory nervous system of […] animal species with the human sensory nervous system” – Bermond refers to this as ‘Romane’s analogy postulate’ (ibid, p.82).
  • 2a. Behaviour as Evidence for Animal Suffering

In Bermond’s first claim (1), he describes and addresses five behavioural research strategies which are used to promote the animal suffering hypothesis. The first and second refer to the results of studies wherein animals are placed in ‘emotion inducing’ situations, and demonstrate the correct physiological and behavioural responses that we would expect to see if they did possess subjective emotional experiences. This, Bermond claims, relies on the assumption that the emotional behaviour and accompanying physiological response in an animal is necessarily tied to its emotional experience “such that the experience of emotion may be assumed to be present if one or more of the other components of the emotional process can be shown to be present” (Bermond, 2003, p.81). But we have reason to think that this is not the case, since it is possible for pain behaviour to occur in absence of pain experience both in humans and non-humans – and likewise, considerable tissue damage might result in little to no pain behaviour, and pain experience can occur in absence of any clear physiological indication of its presence (ibid) (Harrison, 1991, p.23).

The third research strategy takes a similar approach, positing the demonstrability of operant conditioning in animals as proof for their having preferential mental states. In other words; the behaviour of an animal in response to positive and negative reinforcement tells us something about their emotional feelings – namely, that they have emotional feelings to begin with. Again, Bermond argues that the link between behaviour and subjective experience here is not a necessary one – and furthermore, research in humans suggests that operant conditioning can occur without the subject being consciously aware of its taking place (Bermond, 2003, p.81).

To respond: I do not deny the possible disassociation of pain experience from its usually accompanying behavioural and physiological components, but this does not mean that such data is altogether useless (Rivas, 2012, par.5). This is because our inference to animal suffering is not solely behavioural – it is a position that we come to with regard to behavioural and non-behavioural evidence (I shall expand more upon this point in §3a). In addition, it is unclear how Bermond’s second point is (at all) a rebuke, since unconscious cognitive processes form a large part of human cognition, yet we would not conclude that humans lack minds as a result of this. Why does Bermond think that only tests in which the subject is consciously aware of the conditioning process can be held as evidence for inferring their mental states?

According to the fourth strategy, we can infer preferential mental states according to the lengths that certain animals will go to leave or enter a specific environment. Bermond replies by arguing that our behavioural inference to individual mental/emotional states in animals (like ‘hunger’) must be deduced by assuming another such states (‘pain’), but doing so “automatically leads to an endless circular argument” (ibid, p.80). Once more, how does Bermond propose that we differentiate humans from animals on this basis? This method, of inferring the mental states of others on the basis of assuming additional mental states, seems an inaccurate representation of how theory of mind operates – both in humans and animals.

Lastly, one assumes that if an animal’s cognitive capacities are sufficiently advanced, then it is likely that consciousness follows. In his response to this, Bermond claims that “consciousness has no direct access to the cognitive processes which determine […] behaviour”, since it has been demonstrated in humans that higher order cognition can – and does – occur sometimes unconsciously (ibid). Like his response to the third strategy, Bermond makes an error by conflating conscious/unconscious task performance with phenomenal experience in animals (it is the latter which we are interested in). The possibility of unconscious human task performance tells us nothing about an animal’s ability to experience mental states, only that it may be possible for animals – like humans – to perform cognitive tasks unconsciously. This by no means disqualifies animals from having emotional subjective experiences, as Bermond implies (Rivas, 2012, par.8).

2b. (2) Physiology and Anatomy as Evidence for Animal Suffering

The second line of reasoning supposes that on the basis of physical similarities between animals and humans, there is a similarity in the mental states that are experienced. These similarities include the physiological reaction by each in response to specific stimulus, and the likeness of their internal systems (such as nervous system structure and composition) (ibid, 82).

The former of these, unlike the seemingly conscious behaviour which we discussed in §2a, includes the reflexive and unconscious behaviour that is elicited by contact with specific – often noxious – stimuli. It ought to be noted that this nociceptive mechanism which causes an immediate withdrawal from harmful stimuli is separate to and precedes the mental experience of pain, just as “the reflex response to touching something hot precedes the experience of pain” in humans (Elwood, 2011, p.175). Interestingly, Bermond chooses not to address this part of Romane’s analogy postulate. I would argue that it is relevant, insofar as it demonstrates the presence of harm detection/avoidance mechanisms in animals.

The latter of these may seem evident in other mammals, whose internal structure bears a resemblance to humans, and who are equipped with many tangentially similar organs and internal systems. But pain is an emotional experience, and for an emotional experience to take place one reasonably must possess neural structures that are supportive of it. Basing his argument on the supposed neural localisation of mental experience, Bermond puts forward that “[t]he right neocortex and the prefrontal neocortex are both prerequisites for emotional experience” (Bermond, 2003, p.83). Because “subjective experiences can only be studied directly in human beings”, Bermond argues that our inference to the emotional experience of animals must be based on the neuroanatomical similarity of other animals in comparison to ourselves – he concludes that these animals likely only include “anthropoid apes and possibly dolphins” (ibid, pp.83-84).

3. On the Nature of Mental States

Here we reach the crux of Bermond’s argument, his claim that emotional states are brain states, and that only type brains with a sufficiently developed prefrontal cortex and neocortical hemisphere can elicit emotional experiences. The problem with taking this position however is that it is “founded on an outdated concept of the neural localization of mental functioning” which limits mental states from being multiply realizable, and it is not the case that they are type-realizable (or, at least, this is very unlikely to be the case) (Rivas, 2012, par.4). This is the question that Hilary Putnam addresses in his 1967 seminal paper ‘The Nature of Mental States’, in which he considers and rejects both behavioural and brain state theories of mind in favour of a bridging alternative; functionalism, according to which mental states (like pain) are identified as the functional roles they play within an organism. This is because, Putnam argues, the link between mental states and physical states is a matter of realization rather than type-identity (Putnam, 1975, p.437).

3a. Functional Equivalence in Physical Systems

By identifying mental states only in terms of their neuroanatomical correlates (as Bermond does), one does not account for their multiple realizability across different brain states. Such claims, Putnam remarks, are attempted to be made on a similar basis to the claim that “temperature is mean molecular kinetic energy” – despite their fundamental difference in spatio-temporal location (ibid, p.431). A better analogy would perhaps be to compare our inference of pain identity to our inference of object identity. For example, we identify the eye in other species because of the role that it plays in their ability to interpret and process visual stimuli, not on its semblance to the human eye (Van-Gullick, 2009, p.3). This is to show that functional equivalence does not rely on an actual equivalence of circumstances.

We might further the analogy by positing that the absence of a visual cortex in the brains of birds causes them to be blind (Harrison, 1991, p.30). We know this not to be true – even one who believes that birds are no more than unconscious automata (such as Bermond) could not deny that there exists some neurological information processing allowing for its visual environmental navigation. There is, therefore, a functional equivalence in the bird’s neurological systems to our own, insofar as we are both capable of processing and reacting to our visual stimuli, and despite our fundamental difference in brain structure.  Accordingly, we ought to treat the neuroanatomical structures which Bermond puts as responsible for emotional feeling in humans as sufficient – rather than necessary – conditions under which emotion can be felt. Emotional states like pain or hunger are therefore not identical to the brain states which are responsible for their happening – we ought to identify such states with the functional role they play (note that by ‘brain states’ I refer to all relevant physical states that assist in mental functioning – see Rivas, 2012, par.4).

Putnam notes that “similarities in the behaviour of two systems are at least a reason to suspect similarities in the functional organisation of two systems” (Putnam, 1975, p.437). The theory which Putnam puts forward is thus an empirical one, relying on the real-life conference of behavioural data to make claims about mental states (on the grounds of plausibility). By this, Putnam is not suggesting that we identify mental states as behaviour dispositions, rather, by such dispositions, since an animal’s similarity in behaviour (to our own) counts as good evidence toward their having functionally equivalent mental states. It is also worth noting that despite Bermond’s objections on the use of behavioural data in our analysis, his “conclusions about the relation between brain and consciousness are ultimately derived from studies which involve behaviour” (Rivas, 2012, par.6).

3b. Contemporary Methods of Functional Inference

The kinds of evidence which count towards our inference to functional equivalency might, as Bermond suggests, include research on brain structure similitude and correspondence with the occurrence of particular mental states. Despite Putnam’s devaluation of relevant neuroscientific evidence, Andrew Fenton puts forward that the identification of an animal’s brain states with their particular mental states would present a strong case for inferring their emotions, and is plausibly possible (Putnam, 1975, p.437) (Fenton 2012, p.470). Comparatively, “if behaviours are contingently related to mental states, then, unlike brain states, their presence is a weak indicator of the presence of mental states” (ibid). Fenton notes that being able to identify an animal’s brain state with a particular mental state relies on our already having identified that mental state to begin with, but it does demonstrate the relevance and utility of neuroscientific discoveries in addressing the issue of animal minds.

As for the problem of identifying animal minds to begin with, Fenton – like Putnam – argues for the use of behavioural and neuroscientific data in conjunction with one another. “[C]oming to understand the significance of an animal’s behaviour […] requires some knowledge of her natural history, including the proximate function […] of the relevant behaviour and proximate causes relative to the animal’s level of functionality […] and stage of development” (ibid, p.473). Fenton is arguing for behavioural contextualisation – one such method of which calls upon the collation of neuroscientific information that is pertinent to a particular animal’s evolutionary history and mental function. By pairing an animal’s behaviour with the “relevant homologous traits, features, or characteristics of their central nervous system”, our inference to the functional equivalence of their mental states can be strengthened (ibid, p.475).

Examples of such physical-chemical and physiological similarities are perhaps most evident in the species which Bermond mentions in his paper (such as primates, among other mammal species who share the same general neurological structure and composition as humans). But we can extend these similarities to other animal classes. Certain species of annelid invertebrates have been shown to possess physical-chemical systems that allow for their production and reception of pain-related hormones, and hormones associated with panic and stress in humans been discovered in certain cephalopod and crustacean species (Lockwood, 1987, p.76., Elwood, 2011, pp.178-179). Additionally, evidence suggests that certain insects such as cockroaches possess opioid receptors, as have “[d]opaminergic systems essential to reward conditioning […] been identified in the fish forebrain” (Knutsson, 2015, p.16., Droege & Braithwaite, 2014, p.91). This is not to say that the specific hormone receiving systems of these animals are necessarily responsible for their emotional experiences, only that they are sufficient for one another such that they help support our inference to functional equivalency.

We might also contextualise our behavioural inference to animal mental states (as Fenton proposes) by considering the function of pain as an avoidance mechanism, and how the behavioural response to harm would signify pain as a mental experience rather than a non-conscious behavioural disposition (as Bermond would argue). We have already presented evidence for nociceptive systems in animals that are responsible for their possession of harm detection/avoidance mechanisms (§2b), in humans this is usually followed by the mental experience of pain or discomfort. But the nociceptive reflex by itself is not sufficient evidence of pain-type mental experience, as it can occur on separate occasion to “the negative emotional response or feeling associated with pain” (Elwood, 2011, p.175). The function of nociception is for an immediate withdrawal from harmful stimuli, but this “does not imply any long-term motivational change” – we conclude from this that the function of pain is to promote long-term discrimination learning for the avoidance of particular noxious stimuli (ibid, p.181).

While instances of avoidance learning among mammals can be easily thought of, behavioural research on invertebrates suggests the presence of this capacity in fruit flies, who have learnt to discriminate between particular odours depending on their prior association with administered electric shocks (ibid, p.179). Other such arthropods as crayfish and certain crab species have also demonstrated this ability, indicating the non-exclusiveness of mental – specifically pain – experience, which Jeffrey Lockwood notes “may be expected in organisms whose survival can be augmented by the experience” (Lockwood, 1987, p.76). If most animal behaviour is reflexive and lacking emotional experience as Bermond claims, it is unclear how he accounts for this kind of learning.

4. Conclusion

To conclude, Bermond’s critiques of mental state attribution in animals do little to disqualify our reasons we have for thinking that they can – and do – experience a variety of emotional states, including states of suffering. Such animals as we have discovered may include insects among other small animals – the moral duties that arise as a result of this possibility have yet to be clarified, but are important to note. By accounting for the multiple realizability of mental states, Putnam’s functional theory of mind provides a less-conservative basis for mental state inference than competing type identity theories – without overextending and placing the burden of proof on behaviour alone, falling victim to the pitfalls of analytical behaviourism (Putnam, 1975, pp.438-439). We have furthermore demonstrated functionalism to be an adaptive theory of mind, able to alter its research methods in light of relevant new evidence.


Bermond, B., 2003, ‘The Myth of Animal Suffering’ in Armstrong, S & Botzler, R., (eds), The Animal Ethics Reader, pp. 79-85. Routledge: London.

Droege, P & Braithwaite, VA., 2014, ‘A Framework for Investigating Animal Consciousness’, in Lee, G., Illes, J., Ohl, F., (eds), Ethical Issues in Behavioral Neuroscience, pp 79-98. Springer: London.

Elwood, R. W., 2011, ‘Pain and Suffering in Invertebrates?’, ILAR Journal, vol. 52, no. 2, pp. 175-184.

Fenton, A., 2012, ‘Neuroscience and the Problem of Other Animal Minds: Why It May Not Matter So Much for Neuroethics’, The Monist, vol. 95, no. 3, pp. 463-485.

Grush, R., 2002, ‘The Philosophy of Cognitive Science’, COURSE MATERIALS, ver.3.2.

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Knutsson, S., 2015, The Moral Importance of Invertebrates Such as Insects, Master’s thesis, University of Gothenburg.

Lockwood, JA., 1987, ‘The Moral Standing of Insects and the Ethics of Extinction’, The Florida Entomologist, vol. 70, no. 1, pp. 70-89.

Putnam, H., 1975, ‘The Nature of Mental States’, COURSE MATERIALS.

Rivas, T., 2012, The Denial of Consciousness in Non-Human Animals. Avilable from: . [16 December 2017].

Shea, N & Heyes, C., 2010, ‘Metamemory as Evidence of Animal Consciousness’, Springer, vol.25, no.1, pp. 95-110.

Van-Gulick, R., 2009, ‘Functionalism’, COURSE MATERIALS.

Citation style in accordance with the University of Western Australia, Harvard

Word count: 2991

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