Finland achieved repository siting through decades of community engagement beginning in the 1990s. Posiva conducted extensive consultations with Eurajoki residents through what its communications manager called a “long road show” (Gaffney, 2024). In January 2000, Eurajoki’s municipal council approved the repository, choosing not to exercise its legal veto right. Parliament ratified the decision 159–3 in May 2001. Community attitudes were divided: surveys showed 42% favored and 36% opposed disposal (Vehmas et al., 2023). Acceptance stemmed partly from decades of nuclear facility presence since the 1970s—“almost everyone in Eurajoki has a friend or relative who has worked in the nuclear power plants” (El-Showk, 2022)—and partly from Finland’s exceptionally high institutional trust. Economic factors also mattered: the repository generates approximately €20 million annually in tax revenue, nearly half the municipality’s budget (Gaffney, 2024). However, researchers attribute acceptance to “fatigue, adaptation, and tolerance” rather than enthusiasm (Vehmas et al., 2023), with the process becoming “purely technocratic” afterward (El-Showk, 2022). While emphasizing 100,000-year isolation, Finland implemented no systematic exercises for adopting future generations’ viewpoints.

Sweden’s voluntary response approach began in 1992, eventually focusing on two nuclear host communities. The Svensk Kärnbränslehantering AB (SKB; Swedish Nuclear Fuel and Waste Management Company) conducted “large information campaigns to build up trust” and detailed site investigations from 2002 to 2008 (Swahn, 2023). In 2009, Forsmark was selected; municipal councils approved in 2018/2020, followed by government approval in January 2022. Annual polls since 2003 show remarkably high support: 75%–84% consistently, reaching 86% in 2023 (SKB polls). Both communities “took considerable national responsibility” for solving the national waste challenge (IGD-TP, 2022). SKB emphasized its “world leader” role in safety demonstration (Patel, 2022). However, no evidence exists of systematic processes where current residents adopted future generations’ perspectives.

France’s experience starkly contrasts. The Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA; National Agency for Radioactive Waste Management)’s initial site investigations (1987–1990) were “technical and non-participatory,” generating “vehement local opposition” with citizens asking why their community should be “France’s nuclear wastebasket” (Lehtonen, 2023). Despite the 1991 Bataille Law introducing participatory mechanisms, the project has faced “a long and conflict-ridden history of deep mistrust between proponents and opponents” (Barthe, 2006; Lehtonen, 2023). Active opposition continues through groups like Burestop 55 and Bure Zone Libre, with forest occupations (2016–2018) and ongoing protests. A 2020 poll showed 65% of those within 15 km trusted ANDRA, but trust decreased significantly with distance (Vestergaard and Price, 2021). While ANDRA emphasizes “keeping the burden to future generations to a minimum,” the top-down approach left little room for transformative community engagement, much less systematic future generations’ perspective-taking.

All three cases, while achieving important successes through trust-building and compensation, relied primarily on present-generation viewpoints—what FD terms “Present Design.” None implemented systematic exercises where current residents adopted future generations’ perspectives or engaged in host-beneficiary dialogue. Transformational perspective-taking remained absent.

FD theory proposes three human abilities relevant to intergenerational decision-making (Saijo, 2025b): futurability—experiencing present happiness through pursuing future wellbeing; presentability—attending to immediate concerns; and pastability—evaluating past decisions from present knowledge. Each ability corresponds to a design approach: Future Design activates futurability, Present Design engages presentability, and Past Design exercises pastability. Critically, these abilities interact: activating one can enhance others, creating synergistic effects when all three designs are integrated.

The proposed framework follows a sequential workflow consisting of four integrated stages: Past Design (PaD), Present Design (PrD), Future Design (FD), and a final integration stage (Figure 1).

Participants evaluate historical decisions, asking “What did our ancestors build?” for host communities and “How has our consumption created waste burdens elsewhere?” for beneficiaries. This activates pastability: the capacity to recognize ourselves as the “future” of past generations and to critically assess their choices from our current knowledge (Saijo, 2025b). Participants make three evaluations: gratitude when past decisions brought positive results despite uncertainty; criticism when present failures arose from past prioritization of immediate benefits; and indifference when past choices seem neither particularly wise nor harmful.

When critically evaluating past failures, participants construct Alternative History—envisioning what would have happened if different decisions had been made. This exercise mirrors Future History in FD, where participants envision pathways from present to desired future states. This temporal symmetry is crucial: PaD looking back from present to past prepares participants for FD looking back from future to present. Both involve standing at one temporal point and reconstructing pathways to another, creating a cognitive template for temporal perspective-taking.

Empirical research demonstrates PaD’s preparatory effects: participants who first engage in historical evaluation show significantly enhanced future-oriented thinking in subsequent deliberations (Nakagawa et al., 2019). PaD expands participants’ temporal-spatial consciousness, making the cognitive leap to future perspectives less jarring and more natural. In the PaD→PrD→FD sequence, PaD serves as essential cognitive scaffolding for the more demanding FD exercises.

Traditional deliberation from current perspectives represents what most policy processes employ—the approach Finland, Sweden, and France primarily used. PrD focuses on immediate concerns: current risks, existing resources, realistic constraints, and near-term implementation. Participants envision futures by projecting forward from present conditions through back-casting or scenario planning.

However, PrD faces inherent limitations in activating futurability. When participants remain anchored in present perspectives, their temporal horizon tends to compress: concerns about next decade or generation dominate over considerations spanning millennia. The cognitive distance between present and far future remains untraversed. PrD’s strength lies in grounding deliberations in practical reality; its limitation lies in difficulty extending temporal concern beyond directly imaginable futures. For 100,000-year decisions, this temporal anchoring becomes a constraint rather than strength.

In host-beneficiary applications, PrD’s joint sessions surface important baseline assumptions about concentrated risks, dispersed benefits, and mutual dependencies. Yet without temporal perspective shifts, these discussions tend toward transactional frameworks—compensation for burden—rather than transformational recognition of intergenerational service.

Both groups become imaginary future generations—citizens of 2525 or 3000—through temporal relocation rather than mere projection. This distinction matters profoundly: PrD projects future consequences from present starting point; FD requires cognitive leap to future temporal location, then looking back at present. Participants don ceremonial markers (robes, badges), write messages from future to present, and deliberate as if evaluating 2026's choices from 2525's vantage point.

From this future standpoint, participants construct Future History—narratives of how present decisions led to their imagined 2525 reality. This mirrors PaD’s Alternative History but reversed temporally: where PaD reconstructs alternative pasts from present knowledge, FD reconstructs alternative futures from imagined future knowledge. This temporal symmetry—PaD’s backward reconstruction and FD’s forward reconstruction—creates cognitive consistency that facilitates both exercises. Participants who have practiced Alternative History in PaD find Future History more intuitive; they’ve already exercised the mental operation of standing at one temporal point and reconstructing pathways to another.

Embodied practices activate emotional connection to distant descendants: wearing robes symbolizes identity transformation, writing messages creates tangible artifacts of imagined futures, deliberating “as if” 2525 citizens sustains cognitive displacement. Experimental evidence supports FD’s effectiveness: adopting retrospective viewpoints from imaginary future generations increases financially sustainable attitudes (Nakagawa et al., 2019), while negotiating with imaginary future generations improves intergenerational resource allocation (Kamijo et al., 2017).

Research demonstrates that participants experiencing all three designs harmonize immediate concerns with long-term imperatives more effectively than those experiencing only PrD or only FD (Hara et al., 2021; Saijo, 2025a; Saijo, 2025b). Crucially, sequencing matters: PaD→PrD→FD produces more future-oriented thinking in PrD than PrD→PaD→FD, because historical evaluation first expands time-space consciousness before present-focused deliberation begins.

This synergy operates through cross-effects. PaD significantly increases pastability while also enhancing presentability and futurability. PrD maintains these gains while grounding deliberations in practical reality. FD then builds upon this enhanced temporal consciousness to achieve maximal futurability activation. The integration session synthesizes these perspectives, negotiating recommendations acknowledging both host sacrifice and beneficiary responsibility while honoring insights from all three temporal viewpoints.

Nuclear electricity primarily benefits urban populations far from disposal sites. Current processes often isolate host communities, potentially fueling resentment about bearing burdens for distant beneficiaries. FD creates structured dialogues where urban electricity consumers and rural host communities exchange perspectives. Beneficiaries acknowledge dependence; hosts articulate concerns. This mutual recognition can transform repository siting from imposed burden to recognized service, addressing environmental justice’s spatial dimension (Schlosberg, 2003; Walker, 2009): recognition-based rather than merely distribution-based justice. Urban beneficiaries expressing genuine gratitude can cultivate hosts’ collective pride.

When host communities envision future generations’ gratitude, pride arises internally. This requires not just economic benefit but authentic recognition: acknowledgment that host communities perform an ethical service of civilizational significance. When both temporal and spatial perspective-taking occur—current residents embodying future generations and distant beneficiaries recognizing hosts’ service—pride becomes self-sustaining emotional infrastructure.

Unlike Present Design, which projects from present interests, FD seeks to integrate the future’s viewpoint as a foundational element of present deliberation. This represents moral innovation: current people temporarily becoming future people, host and beneficiary communities recognizing mutual dependence.

FD has demonstrated effectiveness in Japanese municipal deliberations (Hara et al., 2019; Hara et al., 2021), but nuclear waste siting presents unprecedented challenges. Rigorous pilot testing comparing FD and non-FD deliberation is essential, measuring not only acceptance rates but reasoning quality and long-term commitment.

Ethical safeguards prevent manipulation. Participants must understand FD’s explicit aim to shift temporal perspective—transparency, not hidden persuasion. Genuine openness to rejection is critical. Independent oversight should monitor facilitation neutrality. FD offers cognitive tools, not predetermined conclusions.

Three-phase implementation could demonstrate FD viability. Phase 1 (Years 1–2): Pilot testing in 2-3 municipalities with existing nuclear facilities, comparing FD and traditional approaches. Outcome measures include acceptance rates, reasoning quality, and commitment stability. Phase 2 (Years 3–4): Refined protocols applied to regional consultations. Phase 3 (Years 5+): Integration into national-level programs alongside consent-based frameworks (DOE, 2023).

FD complements rather than replaces established trust-building mechanisms. Integration requires careful sequencing: initial trust establishment through traditional engagement, then FD exercises to deepen intergenerational commitment. Economic compensation remains important but reframed as recognition of ethical service. Technical safety assessment continues as foundation, with FD adding perspective-taking to societal decision-making.

Anticipated barriers include facilitator quality variance, participant selection effects, and cognitive-emotional demands. Mitigation strategies: rigorous facilitator training; demographically representative sampling; session designs balancing depth with participant wellbeing, including mental health support for emotionally intensive exercises.

Success metrics should assess transformation quality: depth of temporal perspective-taking, host-beneficiary mutual recognition, pride cultivation, and long-term commitment durability.

Several qualifications warrant emphasis. First, FD’s effectiveness demonstrated in Japanese municipal contexts may not directly translate to nuclear waste siting or to cultures with different decision-making norms. Second, comprehensive FD implementation requires substantial time and resources—typically four full-day sessions plus extensive preparation—which may prove prohibitive in some contexts. Moreover, unlike participatory methods relying on external facilitators, FD requires local practitioners (e.g., municipal staff) to lead workshops themselves to ensure local legitimacy and sustainability. This necessitates intensive pre-training where FD experts conduct rigorous sessions until local implementers internalize the methodology and can facilitate independently. This preparatory ‘internalization process'—not workshop complexity itself—constitutes the primary adaptation barrier, requiring substantial organizational commitment and resource allocation. Third, FD addresses societal legitimacy and intergenerational commitment but cannot replace technical safety assessment or geological suitability evaluation. Fourth, skeptics might view FD as adding procedural complexity without demonstrable benefit. These concerns underscore why rigorous pilot testing, comparing FD and non-FD approaches across diverse contexts with demographically representative samples, is essential before broader implementation. Such testing should assess not only acceptance rates but also reasoning quality, commitment stability, and long-term legitimacy.

Recent developments globally suggest growing recognition of consent-based approaches’ importance. Recent U.S. guidance emphasizes consent-based siting (DOE, 2023). Germany and Canada are similarly developing participatory processes (Di Nucci and Brunnengräber, 2023; Cotton, 2017). FD offers these initiatives a complementary methodology that addresses a shared pattern: primary reliance on present-generation perspectives. By systematically incorporating future generations’ viewpoints through Past, Present, and Future Design exercises, and spatial dialogue between hosts and beneficiaries, FD can complement negotiated acceptance by adding a dimension of collective intergenerational achievement.