Giving Consent to the Ineffable.

A psychedelic renaissance is currently taking place in mental healthcare. The number of psychedelic-assisted therapy trials is growing steadily, and some countries already grant psychiatrists special permission to use psychedelics in non-research contexts under certain conditions. These clinical advances must be accompanied by ethical inquiry. One pressing ethical question involves whether patients can even give informed consent to psychedelic-assisted therapy: the treatment's transformative nature seems to block its assessment, suggesting that patients are unable to understand what undergoing psychedelic-assisted therapy actually means for them and whether it aligns with their values. The present paper argues that patients often have sufficient knowledge to give informed consent because they know that they want to change their negative status quo and that psychedelic-assisted therapy offers an effective way to do so. Accordingly, patients can understand what the transformative nature of psychedelic-assisted therapy means for them and a make a value-aligned choice even if they are unable to anticipate the manifestation of a psychedelic experience.

Informed Consent Under Ignorance.

In recent years, an old challenge to informed consent has been rediscovered: the challenge of ignorance. Several authors argue that due to the presence of irreducible ignorance in certain treatments, giving informed consent to these treatments is not possible. The present paper examines in what ways ignorance is believed to prevent informed consent and which treatments are affected by that. At this, it becomes clear that if the challenge of ignorance truly holds, it poses a major problem to informed consent. The paper argues, however, that from both an empirical and a theoretical point of view, it is not convincing that ignorance prevents informed consent. Still, it seems important that the presence of irreducible ignorance is openly discussed during the informed consent process.

With great power comes great vulnerability: an ethical analysis of psychedelics' therapeutic mechanisms proposed by the REBUS hypothesis.

Psychedelics are experiencing a renaissance in mental healthcare. In recent years, more and more early phase trials on psychedelic-assisted therapy have been conducted, with promising results overall. However, ethical analyses of this rediscovered form of treatment remain rare. The present paper contributes to the ethical inquiry of psychedelic-assisted therapy by analysing the ethical implications of its therapeutic mechanisms proposed by the relaxed beliefs under psychedelics (REBUS) hypothesis. In short, the REBUS hypothesis states that psychedelics make rigid beliefs revisable by increasing the influence of bottom-up input. Put differently, patients become highly suggestible and sensitive to context during a psychedelic session, amplifying therapeutic influence and effects. Due to that, patients are more vulnerable in psychedelic-assisted therapy than in other therapeutic interventions; they lose control during a psychedelic session and become dependent on the therapeutic setting (including the therapist). This enhanced vulnerability is ethically relevant and has been exploited by some therapists in the past. Therefore, patients in current research settings and starting mainstream medical settings need to be well informed about psychedelics' mechanisms and their implications to give valid informed consent to treatment. Furthermore, other security measures are warranted to protect patients from the vulnerability coming with psychedelic-assisted therapy.

Rational transformative decision-making.

According to L. A. Paul (2014), transformative experiences pose a challenge for decision theory, as their subjective value is not epistemically accessible. However, several authors propose that the subjective values of options are often irrelevant to their ranking; in many cases, all we need for rational transformative decision-making are the known non-subjective values. This stance is in conflict with Paul's argument that the subjective value can always swamp the non-subjective value. The approach presented in this paper takes Paul's argument into account and shows how potential swamping can be controlled given that one desires the transformative outcome: If one knows from previous decisions that desired transformative outcomes are associated with positive subjective value and if, in addition, testimony confirms this association for the current decision situation, one can infer that a desired outcome's expected subjective value has a positive valence. Accordingly, one can rationally choose the desired transformative option if its non-subjective value is no lower than the overall value of any other option.

How Psychedelic-Assisted Treatment Works in the Bayesian Brain.

Psychedelics are experiencing a renaissance in clinical research. In recent years, an increasing number of studies on psychedelic-assisted treatment have been conducted. So far, the results are promising, suggesting that this new (or rather, rediscovered) form of therapy has great potential. One particular reason for that appears to be the synergistic combination of the pharmacological and psychotherapeutic interventions in psychedelic-assisted treatment. But how exactly do these two interventions complement each other? This paper provides the first account of the interaction between pharmacological and psychological effects in psychedelic-assisted treatment. Building on the relaxed beliefs under psychedelics (REBUS) hypothesis of Carhart-Harris and Friston and the contextual model of Wampold, it argues that psychedelics amplify the common factors and thereby the remedial effects of psychotherapy. More precisely, psychedelics are assumed to attenuate the precision of high-level predictions, making them more revisable by bottom-up input. Psychotherapy constitutes an important source of such input. At best, it signalizes a safe and supportive environment (cf. setting) and induces remedial expectations (cf. set). During treatment, these signals should become incorporated when high-level predictions are revised: a process that is hypothesized to occur as a matter of course in psychotherapy but to get reinforced and accelerated under psychedelics. Ultimately, these revisions should lead to a relief of symptoms.

A rational route to transformative decisions.

According to Paul (Transformative experience, 1st edn, Oxford University Press, 2014), transformative experiences pose a challenge to decision theory since their value cannot be anticipated. Building on Pettigrew's (in: Lambert, Schwenkler (eds) Becoming someone new: essays on transformative experience, choice, and change, Oxford University Press, pp 100-121, 2020) redescription, this paper presents a new approach to how and when transformative decisions can nevertheless be made rationally. Thanks to fundamental higher-order facts that apply to any kind of experience, an agent always at least knows the general shape of the utility space. This in combination with the knowledge about the non-transformative alternative in the choice set can enable rational decision-making despite the presence of a transformative experience. For example, this paper's approach provides novel arguments for why gender transition (cf. McKinnon in Res Philosophica 92(2):419-440, 2015) or staying childfree (cf. Barnes in Philos Phenomenol Res 91(3):775-786, 2015) can be rational.