Epistemic status: I have written this fairly quickly with the goal of getting the gist of the ideas out, rather than trying to make a very rigorous argument. Also, I spent a limited time reading up on patient longtermism, and it might be that I am unaware of or misunderstood relevant arguments. If this turns out to be the case, I apologize and will very happily update.
Tl;dr: The question “What sorts of things store and accumulate impact potential?" ought to be one of the central questions of patient longtermism. We can further break it down into a) exploring what such ‘things’ (other than money), with the desired properties (i.e. storing, accumulation), exist, and b) how to render their impact potential commensurable, so as to be able to assess in which one(s) a patient longtermist would want to invest. I believe this question/frame currently receives not enough attention.
This post provides a good, short introduction to the key tenets of patient longtermism. For a more extensive treatment of the subject, see this paper by Phillip Trammel and this 80,000 Hours interview with Phillip.
I think considerations raised by patient longtermism are important, and I am in favour of acting upon its implication with some of our resources, in view of diversifying our altruistic portfolio. That said, based on the arguments I’ve heard so far, I remain very sceptical of what one might take as a first-order implication: investing most of one’s money to be used in a couple of hundred or thousand years.
Patient Longtermism as a reference frame
Arguments about patient longtermism seem to naturally gravitate to discussing money as the key resource under discussion. I don’t mean to say that patient longtermism necessarily implies that investing money is the best way to act upon its implications, nor that people who have thought about it most suggest it does. However, I believe there currently exists, as a matter of fact, such a tendency. Reasons for why this is the case include the fact that money provides a straightforward way to quantify the discussion, or that we understand things about how it accumulates over time (e.g. historical interest rates). However, limiting our analysis to money would be a mistake.
In particular, I believe that the following ought to be one of the central questions of patient longtermism:
What types of things can store and accumulate ‘impact potential’ over time?
I think we should spend more time thinking about a) what such ‘things’ other than money exist, and b) how to render their impact potential commensurable so as to be able to assess in which one a patient longtermist would want to invest.
I will share a few thoughts on potential contestants for a), and some frugal arguments for how they might compare to money as a means to store and accumulate impact potential.
Types of things that store and accumulate “impact potential“ over time
My number one contestant is knowledge. I believe that knowledge is critical for any attempts of doing good and steering humanity into a flourishing future. Importantly, I also believe that knowledge has similar "accumulative" properties to invested money.
Knowledge created now will have us ask better questions tomorrow; knowledge can create better tools for generating more knowledge; and knowledge creation has the potential to uncover critical considerations, illuminate known unknowns and uncover unknown unknowns. Personally, I think the rationale for investing in knowledge creation is extremely strong. If I was given some large sum of money to spend on altruistic causes, I would invest it in knowledge creation rather than longterm financial investments.
Another contestant, although pretty hard to measure, is something like "civic capacity" or "the quality of our institutions". According to me, there are two main reasons in favour of investing in our better institutions. One, institutional development has high path-dependency. This suggests that improving institutions earlier rather than later might have large payoffs compared to the counterfactual scenario. (Some relevant academic work I am aware of on this topic are from Jenna Bednar, Scott Page, Elinor Ostrom and Douglass North.) Two, institutions interface with nearly every other area of concern, such as economics, science/knowledge creation, innovation, national and international politics. For example, the field of development economics has thought about a version of this issue for some time now and offers a bunch of reasons why investing in good institutions might be extremely "lucrative”, among others because the health of an economy and the nature of its political institutions are tightly linked.
However, this category does to me definitely seem harder to think about than, say knowledge or money. It is, for example, not straightforward how you get better institutions (“tractability concern”). There are many examples of institutional changes that did in fact not lead to an accumulation of positive consequences downstream. In the case of improving institutions in the developing world specifically, there is already an entire sector trying to work away on this, so that's less neglected (“neglectedness concern”).
However, I think it would be a mistake to limit the mission of creating better institutions to development economics. For example, I consider AI governance, or more generally the governance of emergent technologies, as part of this category. I, like many others, believe that this is likely a very impactful issue to work on. As a final example of what we might want to consider part of the “better institutions” bucket is something like “getting our social media and information ecosystem dilemma right”. Lots of money in the future but a very confused and fragmented world is likely not the ideal scenario from an altruistic perspective.