Kant’s ethics relates moral standing to the capacity for reason. But how much sense does that connection make?

Chris W. Surprenant is an associate professor of philosophy at the University of New Orleans, where he directs the Alexis de Tocqueville Project in Law, Liberty, and Morality. He is the author of Kant and the Cultivation of Virtue (Routledge 2014), co‐​editor of Kant and Education: Interpretations and Commentary (Routledge 2012), and has published numerous journal articles in moral and political philosophy.

He holds a BA in philosophy and government from Colby College, and a PhD in philosophy from Boston University.

My last few posts have addressed issues in Kant’s political philosophy that I think are relevant to scholars with libertarian leanings. But for many scholars of varying political orientations, what makes Kant interesting is his moral philosophy, and, in particular, the connection between morality and reason. In contemporary moral and political discussions, one place where this connection is referenced frequently is in the discussion of moral standing, who counts as having it, and why.

At first it does not seem unreasonable to argue that cognitive ability and moral standing ought to be linked, and, further, that moral standing, like intelligence or cognitive ability, can be viewed in terms of degree. Julian Friedland, for example, claims that beings with a higher faculty of cognition deserve greater moral standing than beings with a lower faculty of cognition: “[There are] interests that, say, the ordinary human adult possesses…that other arguably self‐​conscious beings…do not possess. And such interests are not merely novel but morally significant since they represent an entire order of capacities for self‐​consciousness, namely, self‐​determination” (2004). But this position, if taken to its ultimate conclusion and paid with recent scientific findings, seems to present significant problems for developing a robust and sensible account of morality. To see why, we need to examine recent scientific findings that require us to reconsider if the theoretical framework of associating moral standing with cognitive ability is reasonable, and, if so, how that framework ought to be applied in practice.

The argument for associating moral standing with the hierarchy of cognitive abilities, and, especially, the assertion that the highest cognitive faculty is a characteristic normally associated with humans alone, hangs on (1) the assumption that self‐​consciousness and self‐​determination are the primary characteristics central to moral standing; (2) that there exists a hierarchy of self‐​consciousness and the higher a being is on that hierarchy, the greater its power of self‐​determination; and (3) that the hierarchy of self‐​consciousness has a one‐​to‐​one correlation with the hierarchy of cognitive abilities. All of these claims appear problematic. For example, it is not immediately obvious why self‐​determination should be the determining factor when evaluating a being’s moral standing. Why not use some other characteristic that has been associated with moral standing historically, such as whiteness or distance from Athens? ‘Humanness’ or ‘how close a being is to being human’ appears to be the new ‘whiteness’. On this point I agree with Mark Bernstein: “Unless and until we can produce powerful reasons for favoring human interests” and human characteristics, there exists no compelling reason to do so (Bernstein, 2004: 389).

Friedland appears to recognize this problem at the end of his essay, writing, “The murky and confounding moral implications of such considerations will ultimately rely on the detailed results of empirical investigation” (2004). That is, through empirical investigation we can determine what degree of moral standing any particular being possesses. But to most philosophers, this conclusion is bizarre: How can empirical investigation (i.e., determining what is the case) provide us with answers to normative questions (i.e., what ought to be the case)?

Even if we set this problem aside, empirical investigation thus far has shown that human beings are not the only biological organisms to possess intelligence or these cognitive abilities. Many animals possess it as well (Hauser, 2000: 91–115 and 208–9), along with possessing other characteristics normally associated with moral standing, such as being self‐​aware (Shapiro, 2006). Even if we associate higher levels of cognition with higher degrees of moral standing, and identify the possession of discursive, hypothetical reasoning as the highest level of cognition, it is possible that many actions performed by non‐​human animals are the result of this type of hypothetical reasoning and are not merely instinctual (Reiss and Marino, 2001; McCowan and Reiss, 2001; Marino, 2002; Plotnik et al., 2006). Like with other human beings, we have access only to the actions of other non‐​human animals and the empirical data that we are able to collect regarding their brain states, chemical signals being transferred and received, and so forth. Therefore, if we associate moral standing with cognitive abilities as determined by empirical observation, then it is possible, and highly probable, that certain non‐​human animals would have greater moral standing than some human beings. Whether any particular being, human or non‐​human, would have greater or lesser moral standing than any other particular being, human or non‐​human, would depend entirely on empirical data and the degree of cognition that particular being possessed.

A further concern is that empirical data from recent scientific research suggests that the possession of intelligence, self‐​awareness, and other morally relevant characteristics does not stop with non‐​human animals—plants possess these characteristics as well. “Recent advances in plant molecular biology, cellular biology, electrophysiology and ecology, unmask plants as sensory and communicative organisms, characterized by active, problem‐​solving behavior” (Baluška et al., 2009a; citing Baluška et al., 2009b; Brenner et al., 2006; Calvo and Keijzer, 2009; Trewavas, 2005 and 2007; Baluška and Mancuso, 2009). Contrary to the view of plants as passive organisms or, as Aristotle described, organisms possessing the power of self‐​nutrition alone, plants: (1) communicate with other organisms and share aspects of their physiological state through the production and reception of chemical volatiles (Bruin and Dicke, 2001; Pierik et al., 2004; Karban et al., 2006; Arimura et al., 2009; Dicke et al., 2009; Hiel and Karban, 2009); (2) are self‐​aware (Grutman and Novoplansky, 2004) and able to distinguish kin from non‐​kin through the production and secretion of a signaling fluid (Karban and Shiojiri, 2009; Biedrzycki et al., 2010); and (3) “possess a sensory‐​based cognition which leads to behavior, decisions and even displays of prototypic intelligence” (Baluška et al., 2009a; citing Trewavas, 2005; see also Calvo Garzon, 2007; Calvo Garzon and Keijzer, 2009).

The claim that plants possess what can be classified as cognitive abilities is not new. In 1880, Charles and Francis Darwin published The Power of Movement in Plants, which examined, among other things, how plants could possess these abilities without possessing a brain. In the last sentence of the last paragraph, he concludes:

It is hardly an exaggeration to say that the tip of the radicle thus endowed, and having the power of directing the movements of the adjoining parts, acts like the brain of one of the lower animals; the brain being seated within the anterior end of the body, receiving impressions from the sense‐​organs, and directing the several movements. (1880: 428)

Following the Darwins’ observations, recent research has focused on the apexes of plant roots. This research has shown that a very small region of the root apex, referred to as the “transition zone” (Verbelen et al., 2006), consumes more oxygen than any other part of the plant (Baluška et al., 2004; Masi et al., 2009; Mancuso, 2010). More importantly, the cells in this transition zone send and receive the same chemical signals used by the neurons in the brains of humans and other animals to exchange information (Baluška and Mancuso, 2009; Mancuso, 2010). Although only a few hundred cells in any particular root display these characteristics, a typical small plant contains more than eleven and a half million root apexes, and each particular root apex works in network with all the others (Baluška et al., 2005; Baluška and Mancuso, 2009; Mancuso, 2010). In short, the root structure of plants is remarkably similar to the brains of humans and non‐​human animals in terms of structure, the electrochemical signals that are transmitted and received, and the function served by the transmission and reception of these signals.

Therefore, while cognitive abilities may differ both in kind and degree, it is the case that these differences necessarily correspond with different species. One consequence of these recent developments in plant research is that if moral standing is extended to beings based on some sort of technical understanding of cognition or self‐​awareness, then many plants may possess moral standing. If moral standing admits of degrees, then it may be the case that many individual plants could possess greater moral standing than many individual human beings or non‐​human animals. Although it is certainly the case that the majority of animals (both human and non‐​human) would possess greater moral standing than the majority of plants, the degree of moral standing possessed by any particular being would be determined by examining the empirical data relative to that being’s cognitive abilities. At the very least the results of these recent scientific investigations require us to reconsider whether or not the theoretical framework of associating moral standing with cognitive ability is reasonable, and, if so, how that framework ought to be applied in practice.

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