Was den Menschen zum Menschen macht

Brain-Computer Interface (BCI)

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🇩🇪 Deutsche Version: Brain-Computer-Interface (BCI)

A brain-computer interface is a technical system that couples neural signals directly with a computer — either by reading out (the bearer controls a device with thoughts) or by writing in (the device stimulates brain tissue). The coupling can be invasive (microelectrodes in the cortex), endovascular (an electrode array placed transvenously on the cortical surface), or non-invasive (electroencephalography, EEG).

In terms of personhood ontology, the BCI is a tool, not a constituent. It changes the mode of actualization of a bearer of intelligence (deutera energeia), not the essential form (prote energeia). A human being with a BCI remains fully a person — the implant extends the faculty for actualization, but creates no new substance and erases no existing one.

Ontological classification: Superordinate concept: Technical augmentation; subordinate concepts by type of intervention: invasive, endovascular, non-invasive; subordinate concepts by purpose: Therapeutic BCI, Enhancement BCI.

Three Clinical Paradigms

Invasive microelectrode arrays — the electrode array is placed intracortically by craniotomy. Highest signal resolution, highest surgical intervention. Realized in two designs: rigidly anchored silicon arrays with typically 96 or more electrodes (academic study line since 2004) and flexible microthread arrays with several hundred to over a thousand channels (commercial systems since 2024).

Endovascular stent electrode — the electrode array is advanced transvenously via the jugular vein to the inner surface of the superior sagittal sinus, where it rests against the surface of the motor cortex. No cranial intervention. Published clinical studies in the USA with positive 12-month outcomes for six first patients.

Non-invasive procedures — electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), magnetoencephalography (MEG). Lower signal resolution, no surgical intervention. Clinically relevant especially for patients in the completely locked-in state (CLIS) through voluntary frequency-band modulation.

The AI Component

Every BCI decoder used in practice is a learning system (artificial intelligence): it translates neural activity into motor or communicative output by means of models adapted to the bearer’s training data. In substance-ontological terms, this changes nothing about the tool-determination — the decoder remains an aid in the service of the bearer. Ethically, however, the demand for mental privacy and mental integrity grows, because the learning system has permanent access to neural data and its decisions are only partially traceable (cf. Yuste et al. 2017; Ienca & Andorno 2017).

The Case in Point — First Commercial Microthread Implantation 2024

In January 2024, a patient rendered tetraplegic by a diving accident received, as the first human being, a flexible microthread implant. After eighteen months of use, he is again studying neuroscience, controls computers, games, and smart-home devices with his thoughts, and describes the control in a public interview roughly as follows: instead of trying to move his hand, he merely thinks of the desired cursor position, and the cursor follows. This is phenomenologically interesting, because here the boundary between voluntary action and predictive decoder output becomes blurred — yet in substance-ontological terms it is no new question: the faculty remains with the bearer, the actualization is technically accelerated.

The patient describes himself as a believing Christian and has given his implant a name of its own. The dividing line between implant as restitution and implant as self-deification does not run along ideological lines, but along the therapeutic versus enhancement purpose.

Methodological Point

Whoever conceives the BCI as a mere prosthesis misses the ethical span between the ALS patient and the enhancement consumer. Whoever celebrates it as a cyborg transition into a new species misses the ontological constancy of the person. The differentiation by type of intervention and purpose keeps both risks in view.

Ethical Classification according to Personhood Ontology

Personhood ontology delivers no blanket judgment for or against BCI, but a differentiating evaluation by purpose. In substance-ontological terms, the BCI is a tool; ethically it becomes what its use makes of it.

Legitimate — and in borderline cases even required is the therapeutic BCI. In completely locked-in ALS patients, the restitution of the capacity to communicate is not comfort, but the precondition for the person to be able to manifest herself in the personal community at all. The dignity of the person exists regardless of whether the channel functions — but the address that constitutes personhood and answers it needs a channel that lets the answer through. Where medicine can restitute this condition of answering, the personalistic norm commands it not merely as permitted, but as owed help. This is in line with the Magisterium: in his message to the Pontifical Academy for Life, “AI and Medicine — The Challenge of Human Dignity” (message of 7 November 2025, congress 10–12 November 2025), Pope Leo XIV confirmed precisely this line.

Not legitimate is the enhancement BCI in its pure form — the intervention in healthy persons to surpass the species-specific normal performance. It treats personhood as an optimizable substrate and aligns itself with the logic of transhumanism, which Spaemann and the personalistic tradition have rejected. This rejection is not hostility to technology, but an expression of the distinction healing versus self-deification: the person is not her own creator.

Even the legitimate therapeutic BCI is subject to four ethical conditions that follow from personhood ontology:

  1. Genuine indication — illness or injury, not a marketing label. Whoever declares enhancement to be therapy manipulates not only the regulation, but also the ethical judgment.
  2. Informed, revocable consent — the person may never be made the object of a treatment to which she cannot consent or which she cannot leave again. In cases of limited capacity to consent (dementia, severe late-stage ALS, children), stricter conditions apply.
  3. *Preservation of neurorights — mental privacy, mental integrity, and cognitive liberty are not suspended by the therapeutic indication. They also structure the relationship between patient and provider, patient and manufacturer, patient and insurer.
  4. Social justice — access to therapeutic BCI care must not be tied to purchasing power. Otherwise a two-tier medical system arises that violates distributive justice.

Substance-ontological clarification. The patient becomes, through the implantation, at no moment less a person. The BCI is no anthropotechnics in the sense of an alteration of essence; it is an aid to actualization that neither gives the person her identity nor takes it away. Whoever celebrates the BCI as a “transition to posthumanity” or vilifies it as a “loss of humanity” misses the ontological state of affairs — the person is, before, with, and without the implant, the same.

Counterargument. A sharper position would reject even therapeutic BCI, on the grounds that every chronic human-machine entanglement deforms the person in the long run and produces dependency. The personalistic answer: the same concern applies to dialysis, the cardiac pacemaker, and the cochlear implant — it is to be taken seriously, but it argues for careful indication and good accompaniment, not for blanket rejection. The line healing versus self-deification carries the differentiation without falling into fear of technology.

BCI applications are subject to the emerging neurorights: mental privacy (protection against non-consenting readout), mental integrity (protection against manipulative writing-in), and cognitive liberty (self-determination of mental processes). Chile became, in 2021, the first country to establish constitutional protection of neurorights; the UNESCO Recommendation on the Ethics of Neurotechnology followed in 2025.

Sources: Generated by querying the Personhood ontology. Research status 7 June 2026 (dossier HCI / BCI — worldwide research).

Further sources:

  • Neuralink (2026): Two Years of Telepathy. Company report on the status of the N1 implantations, January 2024 to early 2026.
  • Synchron Inc. (2024 / 2025): COMMAND Trial — 12-month outcomes. Endovascular BCI in six US patients.
  • BrainGate Consortium (2025): Long-term performance of intracortical microelectrode arrays in 14 BrainGate clinical trial participants. medRxiv preprint of 2 July 2025, DOI 10.1101/2025.07.02.25330310.
  • Gruica, M. (2025): The Ethical Significance of Brain-Computer Interfaces as Enablers of Communication. Voices in Bioethics 11.
  • Center for Bioethics and Human Dignity (2025): Brain-Computer Interface Technology’s Impact on Human Personhood, Identity, and Dignity. Dignitas 32 (3-4).
  • arXiv 2507.00305 (2025): EEG-Based Auditory BCI for Communication in a Completely Locked-In Patient.

See also

Generated by querying the Personhood ontology.

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