With regards to the recent dos + inflation bug, and seeing that most nodes on the network have still not upgraded with the patch (lukedashjr's chart here: https://luke.dashjr.org/programs/bitcoin/files/charts/security.html), I think the least understood aspect of Bitcoin to me is this idea of economic majority. Can you someone elaborate on the economic majority? Suppose in a scenario, I have a node running following the rules of Bitcoin Core v0.17.0 and if I die, but I still want those rules to be enforced, can I do that? Do ancestor nodes have any consensus role to play or only the ones being used today ("economic" nodes, i.e. exchanges, miners, merchants) matter?
the recent dos + inflation bug
That would be CVE-2018-17144
Can you someone elaborate on the economic majority?
A definition from Concensus as a service, Swanson, 2015
A consensus mechanism is the process in which a majority (or in some cases all) of network validators come to agreement on the state of a ledger. It is a set of rules and procedures that allows maintaining coherent set of facts between multiple participating nodes. In the case of Bitcoin, the “longest chain” – the chain with the most proof-of-work – is considered to be the valid ledger.
Active nodes reject transactions or blocks that don't meet the rules. If some nodes have a different set of rules, there can be effectively a fork in the blockchain.
Ultimately it is the longest version of the blockchain that prevails. This has the most proof-of-work embodied in it.
In the case of the bug mentioned, as more nodes get upgraded, they will reject any blocks that contain transactions that attempt to exploit the bug. There will be invalidated blocks.
Only active nodes play any part in enforcing concensus rules. Nodes which are not currently propagating transactions or blocks play no part in this.