[ 28/August/21 ]
A realistic answer to this question is deeply complex, and many of the answers given contain very small subsets of a much bigger picture.
Probably the single largest contributor to instabilities is the use of markets to measure value, and the downstream consequences that flow from that in terms of the incentive structures created. A couple of other answers point to an aspect of this, the fact that war is profitable for some; but that is only actually a tiny part of the real problems with markets.
The biggest issue with markets is that they require scarcity to function. A market measures value in exchange, and we only go to markets when we have a need of something. Oxygen is arguably the most important thing to any of us, yet it has no market value, because we can all get what we need simply by breathing. When most things were genuinely scarce, this wasn’t an issue. Markets are a reasonable mechanism for allocating genuinely scarce products. The issue we now have is that we have automation. I started a software company 35 years ago and have operated it ever since. I started programing computers 48 years ago. I know a little bit about automation and its impacts. Automation allows the production of an ever increasing set of goods and services in universal abundance, but having anything universally abundant drives its market value to zero, by definition. Thus there is no economic incentive to actually meet the reasonable needs of everyone, even though it is actually quite easily achievable. The incentives of markets, capital and profits, are to maintain enough scarcity to maximize the generation of profit. That creates fundamental unfairness, and that creates conflict.
In times prior to fully automated systems, one could make a reasonable case that markets were a very useful tool at multiple levels. In the presence of the sorts of automation available today, one can no longer make that case.
That whole class of issues (and it is a very large class of issues, with some very deep and complex issues) is only one class of many.
Another very complex suite of difficulties for maintaining peace comes from our tendency to prefer simplicity (and its associated certainty) to accepting the uncertainties of complexity that actually seem to be present in every level of reality.
If one builds a sufficiently deep understanding of the strategic underpinnings of the evolution of complexity, it becomes clear why that is so, as evolution tends to punish slowness much more harshly than slight inaccuracies. Thus our entire ability to perceive and comprehend anything about ourselves or reality is built on multiple levels of simplifications that were near enough to survive in the contexts of our ancestors; but might not be quite so useful in our rapidly changing technological present and future. This too is a very deep suite of issues, and requires years of study and abstraction from disciplines such as games theory, evolutionary biology, animal behaviour, neurology, AI and systems theory.
Understanding that what we each perceive of as reality is in effect our own personalized Virtual Reality (VR) created by multiple levels of subconscious processes selected primarily for speed and low energy consumption rather than accuracy, takes a bit of getting used to. Whatever Objective Reality (OR) actually is, it is very unlikely to be what we experience.
But most people are operating from such low resolution models that they do not have uncertainty, reality does actually occur for them as binaries, as True or False, as Friend or Enemy, Right or Wrong – without there being anything in between. Reality seems, beyond any shadow of reasonable doubt, to be much more complex and nuanced than that (containing infinite classes of non-binary logics), always. And under stress we are all biologically constructed to produce such simple models, as they aid in making rapid decisions. Keeping people in a state of stress does not support their being able to accept and respect the diversity that must result from any real expression of freedom. The more stressed we are, the more our simple models drive us to conflict, necessarily. The economic incentives already mentioned, to keep most people in a state of stress, do not help in this dimension of peace either.
Then there is dimension of popular dogma.
Common dogma has it that competition is good for freedom. Actually, that is false. All real domains of complexity are built on new levels of cooperation. Any real expression of freedom is optimized in cooperative contexts. Competitive contexts drive systems to some set of minima on the available complexity “landscape” (in other words, minimize freedom).
So the popular notion that competitive markets enhance freedom, is wrong (and any freedom that is without appropriate responsibility is necessarily self destructive).
The popular notion that evolution is all about competition, is wrong.
The truth about evolution, when considering organisms as complex as we are, is that it is fundamentally based in cooperation, and anything that threatens that cooperation is a threat to our very existence.
So both of the popular dogmas above are a threat to peace, as they oversimplify complex realities to the point of creating existential level risk.
To have peace, we need systems that deliver security and reasonable abundance to all.
In an age of modern automation, there are no technical barriers to delivering such systems, the barriers are those imposed in the systems and beliefs that are present, that are too simplistic for our modern reality.
We need new levels of cooperation, between all levels and classes of agents present, and cooperation is nothing like control.
That is possible, and doable, and it needs to be done.