(1) Feinberg (1974) argues that animals should have rights but plants should not.
(2) Stone (1972) argues that some plants and natural environments should have rights.
(3) Hayward (1998) argues that the circle of rights should not be extended, but that ecological values should be enshrined in our social constitutions, as a natural extension of the logic of human rights.
(4) Attfield (1981) argues that plants cannot be rights bearers but that they can nevertheless be said to have 'interests' and 'value of their own'.
All four articles were interesting, but for now I'll just consider the following proposal by Feinberg (1974):
Interest PrincipleI think that 'interests' may be a necessary but not sufficient condition for moral standing. Here are two definitions of 'interest':
The beings who can have rights are precisely those who can have interests.
1. the advantage or benefit of a person or groupWe can talk of animal or even plant 'interest' in the sense of both (1) and (2). What about the 'interest' of a river? If a plant's interests include striving towards the sun, absorbing nutrients and reproducing, do a river's interests include flowing downhill and out to sea? The ascription of 'interests' seems to be a case merely of teleological interpretation, and not a description of metaphysical fact. We look at these entities and ascribe certain 'goals' to them on the basis of their behaviour. We should be hesitant about taking these characterisations to be literally or metaphysically true.
2. a stake, share, or involvement in an undertaking, esp. a financial one
What would it be for an ascription of 'interests' to be literally true? For plants and rivers to really have goals? Well, I think we consider interest ascription to animals to be 'more' true, and interest ascription to humans even more so.The notion of goals - and thus 'interests' in the sense relevant to moral standing - is closely related to psychology, to the concepts of mental states and intentionality. We might therefore refer to these more general debates in the philosophy of mind (e.g.. Dennett's 'intentional stance') in the hope of clarifying the kinds of beings that can have 'interests'.
Traditionally, moral theories have considered the capacity for 'intentional' behaviour to be a necessary and sufficient condition for moral standing. It seems that Stone (1972) is trying to move away from the idea of intentionality as unique characteristic of the mental. It strikes me that if we take an anti-realist view on intentionality* then we can't possibly use it as the basis for moral consideration. And of course, if we take a spectral view then any moral theory which refers to intentionality will of course need to specify the order of interpretation at which story about 'interests' becomes morally relevant.
The worries about this approach have somewhat reinforced my inclination towards moral non-cognitivism, or at least the view that emotional ties to things provide the basis for giving them moral consideration.
Notes:
* Dennett (1989) rejects the label anti-realism, taking intentional idiom to pick out 'real patterns' in the natural world. But, I think that refusing to recognise intentionality at the ontological level counts as anti-realism in a certain sense. In any case, I think the intentional stance has to amount to a spectral view of intentionality - it's not an all or nothing concept, just a way of understanding complex objects (e.g. in particular, humans). So, his view is still likely to give traditional moral theorists a headache.
References:
Attfield, R. (1981) 'The Good of Trees', Journal of Value Inquiry 15, pp.35-54
Dennett, D. (1989) The Intentional Stance (Cambridge: MIT Press)
Feinberg, J. (1974) 'The Rights of Animals', in Philosophy and Environmental Crisis, Blackstone, W. (ed.) (Athens: University of Georgia Press)
Stone, C. (1972) 'Should Trees Have Standing', in University of Southern California Law Review 45, pp. 450-501
Hayward, T. (1998) 'Political Theory for a Sustainable Polity' in Political Theory and Ecological Values (Polity Press)