Philosopher Axel Gosseries, one of the leading scholars in intergenerational justice, makes a claim that stops most people cold: future generations hold legitimate rights against us right now. Not metaphorically. Legally and morally. The Juliana v. United States case put that claim before a federal court, with children and grandparents forming coalitions to argue that present policy decisions violate the rights of people not yet born. That is not activism dressed as philosophy. That is philosophy with legal teeth, Alan. Last lecture established that our built environments are moral spaces — that urban design either fosters human dignity or quietly erodes it. Intergenerational justice extends that logic across time, not just space. The moral question is no longer only who lives near the highway, but who inherits the planet we leave behind. Intergenerational justice differs sharply from intragenerational justice, which addresses immediate concerns like gender equality and wealth distribution within a single generation. The temporal scope here is categorically different — we are talking about outcomes a hundred years or more into the future, reaching grandchildren's grandchildren's children and beyond. Most people cannot fathom that timescale. That failure of imagination, Alan, is precisely the problem. The current economic model is unjust by this standard because it prioritizes short-term gains over long-term sustainability, often ignoring the rights of future generations. Scholars call this temporal selfishness — the tendency of present generations to pursue policies that concentrate benefits now while distributing costs forward. One key claim of intergenerational justice is distributive: present generations may be morally obligated not to pursue policies that impose unfair distributions of costs and benefits across time. Natural capital — clean water, stable climate, biodiversity — should be preserved for future generations, emphasizing our duty to maintain these resources. There is a philosophical challenge worth naming honestly. The Non-Identity Problem, introduced by Derek Parfit, challenges us to consider the rights of future generations, whose existence hinges on today's decisions. A different energy policy produces different people. So who, exactly, are we harming? Intergenerational justice scholars respond with a sufficientarian answer: regardless of identity, we are obligated to ensure adequate conditions for whoever exists. The person-affecting view — that an act is wrong only if it harms someone who will exist — does not dissolve the duty. It sharpens it. Viewing the Earth as a gift rather than a resource forms the philosophical basis for intergenerational justice, emphasizing our duty to future generations. Gifts carry obligations; resources invite extraction. Indigenous traditions of deep stewardship have long encoded this logic — a sense of collective responsibility that looks beyond any single generation's interests. Environmental sustainability, then, is not a policy preference. It is a fundamental duty of justice toward people who cannot yet speak for themselves. The shift required is from short-term gain to long-term thinking — and that shift, as Laudato Si' insists, begins with recognizing that the future is not ours to mortgage.