Sensing and signalling are automatic chemistry, not evidence of awareness

The argument

Critics of plant consciousness accept the findings and dispute the interpretation. That plants grow towards light, orient to gravity, close on contact and emit compounds when damaged is not in question. The objection is that each of these is a chemical or physical process that runs the same way every time the trigger is present, with no room for and no need of anything it is like to undergo it. The argument is that responsiveness is a poor test of awareness because it is so widely shared. Single cells move along chemical gradients. Immune systems distinguish self from other and mount targeted responses. A thermostat detects a state of the world and acts on the detection. If sensing plus response were sufficient for consciousness, then consciousness would be nearly everywhere, and the concept would stop marking any distinction worth drawing. The proponent's criterion, on this view, proves too much. Critics further argue that the language used to describe plant behaviour is doing illegitimate work. Words such as communicate, warn, remember, decide and learn are borrowed from creatures with minds and applied to chemistry, after which the borrowed connotation is read back out as a finding. A plant does not warn its neighbours; it emits a compound that neighbouring tissue reacts to. Describing the first as the second is accurate, and the appearance of mentality disappears when the metaphor is withdrawn. Because the behaviours offered as evidence are automatic biochemical responses that do not require any accompanying experience, this argument concludes, plants are not conscious and the impression that they are is an artefact of how their behaviour is described.

Premises

Counter-arguments

Proponents reply that the objection proves too much in the other direction, since neural processing is itself chemical and electrical, and calling a process automatic does not show that nothing accompanies it. They point out that much plant behaviour is modulated rather than fixed: plants adjust to conditions previously encountered and reallocate growth as circumstances change, which is not the repetition a purely mechanical system would produce. Withdrawing the mental vocabulary, they argue, does not dissolve flexible behaviour that still needs explaining.

Rejecting the premises

[Rejecting P1] That a process is chemical and physical does not distinguish it from what occurs in a nervous system, which is also chemical and physical. Running identically whenever the trigger is present is a claim about regularity that holds of much animal reflex too, and the premise does not say what work it is doing. [Rejecting P2] Single cells, immune systems and simple machines are offered as agreed cases of unaware response, and that agreement is the premise's own assumption. An opponent who holds that awareness comes in degrees accepts the comparison and denies the conclusion. [Rejecting P3] Warning and remembering may well be borrowed vocabulary, which is a point about description rather than about the plants. The argument needs the processes themselves to lack awareness, and showing that the words overreach does not show that.