The plant is an animate substance with a vegetative soul. It bears a natural end — the finis naturalis: nutrition, growth, reproduction — but it possesses neither the capacity for sensation nor consciousness. It is thereby categorially distinct from the higher animal and, all the more, from the person.
Paradigmatic are the tree and the flower: animate, self-sustaining wholes that grow, nourish themselves, and reproduce — but perceive nothing, suffer nothing, will nothing. Since Aristotle, the philosophical tradition has called this lowest principle of life to threptikon, the vegetative soul.
The vegetative soul
The vegetative soul (anima vegetativa; Greek τὸ θρεπτικόν) is the lowest principle of life as such. Aristotle develops it in De anima II.2—4 (412a—416b) as the common principle of life of all living beings, which is at work in plant, animal, and human — in the plant as the sole principle, in animal and human together with higher principles.
In Summa theologiae I, q. 78, a. 2, Thomas Aquinas systematically sets out the three powers of the vegetative soul:
- vis nutritiva (the nutritive power) — preservation of the individual (esse individui)
- vis augmentativa (the augmentative power) — quantitative development up to the size proper to the species
- vis generativa (the generative power) — preservation of the species (esse speciei)
The vegetative soul acts exclusively upon its own body (non extenditur ultra corpus cui unitur). It produces no perception, no movement as a response to a perceived counterpart — the plant orients itself toward the light, but it does not see the light.
The scientific finding: a plant without consciousness
Since the 2000s, the debate on “Plant Neurobiology” (Mancuso, Baluška, Trewavas) has advanced the thesis that plants possess a rudimentary form of cognition, consciousness, or even “intelligence.” Against this thesis stands the scientific consensus:
Taiz et al. (2019), Trends in Plant Science 24(8), 677—687: “Plants Neither Possess nor Require Consciousness.” The core claim of the eight-member team of authors (Lincoln Taiz, Daniel Alkon, Andreas Draguhn, Angus Murphy, Michael Blatt, Chris Hawes, Gerhard Thiel, David Robinson):
- Plants possess signal processing (calcium waves, electrical action potentials, hormone networks, gene-expression patterns).
- They possess no central nervous system, no neurons in the neurobiological sense, no synaptic connections between excitation-conducting cells.
- They possess no nociception in the animal sense — no sensation of pain, no affective processing of states.
- They possess no subjectivity and no demonstrable capacity for sensation.
The scientific finding thus underpins the philosophical distinction: plants live, but they do not feel. The intra-organismic signal processing of the plant is non-subjective — it produces no experience.
Dignity of living beings: the Swiss special path
Switzerland is the only country worldwide that grants plants a moral status of their own in its constitution:
- Swiss Federal Constitution, Art. 120 para. 2 (in force since 1 January 2000): the Confederation legislates on the use of “reproductive and genetic material from animals, plants and other organisms” and, in doing so, takes account of the “dignity of living beings” (Würde der Kreatur) as well as the safety of human beings, animals, and the environment. The inclusion of plants follows directly from the wording (“animals, plants and other organisms”). Background: the 1992 referendum on genetic engineering, which led to the inclusion of the protection of living beings in the constitution then in force.
- ECNH (2008): The Dignity of Living Beings with Regard to Plants. The Federal Ethics Committee on Non-Human Biotechnology concretizes the concept for plants: plants have a good of their own (an end-in-itself character in a weak form); a purely instrumental treatment is permissible, but not arbitrary — arbitrary harm requires moral justification.
The dignity of living beings is not identical with the ontological dignity of the person. It is a graduated moral status — weaker than personal dignity, but real. It does not demand that plants not be used; it demands that their use not be arbitrary, not contemptuous, not gratuitously destructive.
Finis naturalis
The finis naturalis is the teleological directedness of an animate being toward self-preservation, growth, and reproduction (Aristotle, De anima II.4, 415a23—26). It is the basic form of teleological purposiveness proper to every living thing.
The finis naturalis of the plant is purely biological-teleological: seeds become seedlings, seedlings become full-grown plants, plants become seed-bearing parents of the next generation. It is not a reflected end-in-itself as in the human being, not an affectively experienced end as in the higher animal — but it is a real end, grounded in the nature of the plant.
Order of dignity
The ontology locates the plant within the hierarchy of dignity:
Person > higher animal > lower animal > plant > purely material substance.
Ontological dignity belongs exclusively to the person. The higher animal possesses an intrinsic value owing to its capacity for sensation. The plant possesses — according to the Swiss legal and ethical conception — a weaker form of the “dignity of living beings” arising from its finis naturalis and its end-in-itself character in a weak form. This is categorially distinct both from personal dignity and from the intrinsic worth of the animal.
Ontological classification
- Superordinate concept: animate substance (substance with a principle of life)
- Principle of life: vegetative soul
- Teleology: finis naturalis (nutrition, growth, reproduction)
- Capacity for sensation: no (Taiz et al. 2019)
- Moral status: dignity of living beings (Swiss legal concept, Federal Constitution Art. 120 para. 2)
- Disjoint with: higher animal, person, Human Person (categorially distinct in essence)
Ontological relations
- has soul: vegetative soul (without sensitive or rational part)
- has finis naturalis: finis naturalis (self-preservation, growth, reproduction)
- surpasses in dignity: purely material substance
- is essentially different from: higher animal, person, Human Person
- stands under: dignity of living beings (Swiss legal concept)
Sources
Generated by querying the Personhood ontology.
Further sources:
- Aristotle, De anima II.2—4 (412a—416b). Classical grounding of the tripartition of the soul (vegetative, sensitive, rational). The threptikon (II.4, 415a23—26) as the common principle of life of all living things, comprising nutrition, growth, and reproduction. Perception presupposes the vegetative soul, but not conversely (II.3, 414a32-b1).
- Thomas Aquinas, Summa theologiae I, q. 78, a. 2 (Prima Pars, composed ca. 1265—1268 in Rome). Question of the article: “Utrum convenienter distinguantur vegetabilis animae partes in nutritivum, augmentativum et generativum” — systematic unfolding of the three powers of the vegetative soul: vis nutritiva, vis augmentativa, vis generativa.
- Taiz, Lincoln; Alkon, Daniel; Draguhn, Andreas; Murphy, Angus; Blatt, Michael; Hawes, Chris; Thiel, Gerhard; Robinson, David G. (2019): Plants Neither Possess nor Require Consciousness. Trends in Plant Science 24(8): 677—687.
- Swiss Federal Constitution (SR 101), of 18 April 1999, in force since 1 January 2000, Art. 120 para. 2: “The Confederation shall legislate on the use of reproductive and genetic material from animals, plants and other organisms. In doing so, it shall take account of the dignity of living beings as well as the safety of human beings, animals and the environment, and shall protect the genetic diversity of animal and plant species.”
- Federal Ethics Committee on Non-Human Biotechnology (ECNH) (2008): The Dignity of Living Beings with Regard to Plants. Moral Consideration of Plants for Their Own Sake. Bern, April 2008.