WIP: Expanding policy rooms to reputation

proposals/XXXX-expanding-policy-rooms-to-reputation.md

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+# MSCXXXX: Expanding Policy Rooms towards Distributed Reputation
+
+The Matrix network and protocol are open. However, some users, rooms or servers (let's call them
+"entities") may not play well together, which results in the necessity to kick, ignore or ban
+entities from individual rooms, spaces or other groups of rooms. This happens in particular when
+a user or an entirey homeserver adopt toxic behaviors, such as bullying or attempting to brigade
+other users. As it turns out, kicking, ignoring or banning entities is a complicated task in
+presence of federation. To aid with such actions, MSC2313 defines a vocabulary for storing,
+publishing and sharing *recommendations* on entities, in particular banning.
+Individual users, room or space moderators or even homeserver administrators may either issue
+such recommendations or follow existing recommendations, in both cases letting clients/bots/homeservers
+that implement this spec take the necessary actions.
+
+In many cases, however, banning is too boolean. Actually deciding whether an entity should be banned
+(or muted, or throttled, or any other possible recommendation) is something that may need to be decided
+after taking into account several sources. For instance, a community may decide to adopt a policy
+through which a user is banned from the entirey community if they behave as a troll on at least three
+of their rooms. If they behave as a troll in a single room, they should perhaps get away with a warning,
+or perhaps be muted for 15 minutes, etc.
+
+To achieve this, we need two mechanisms:
+- a mechanism to store, publish and share the *opinion* of a community (or a single user) on an entity;
+- a mechanism to store, publish and share actual *actions* against an entity (such as kicking or muting).
+
+The current proposal builds upon policies introduced in MSC2313 to serve as the former, letting
+communities share their opinion of an entity as a number in [0, 100). Further tools may be developed
+to take action against entities based on the collation of opinions.
+
+We stress out that the Matrix network itself is neutral: it has no opinion on users or content. Different
+communities are bound to have different opinions on entities. This mechanism is solely intended to simplify
+writing tools that aid communities and individuals that trust each other's judgement help protect each other
+against entities that they judge malicious or toxic to their own well-being.
+
+## Proposal
+
+MSC2313 defines `m.policy.rule.<kind>` state events, as follows:
+
+```jsonc
+{
+    "type": "m.policy.rule.user", // Or `m.policy.rule.server` or `m.policy.rule.room`.
+    "state_key": "rule_1",        // Arbitrary.
+    "content": {
+        "entity": "@alice:example.org",
+        "recommendation": "m.ban",
+        "reason": "undesirable behaviour"
+    }
+},
+```
+
+We expand this to:
+
+```jsonc
+{
+    "type": "m.policy.rule.user", // Or `m.policy.rule.server` or `m.policy.rule.room`.
+    "state_key": "rule_2",        // Arbitrary.
+    "content": {
+        "entity": "@darthvader:example.org",
+        "recommendation": "m.opinion",
+        "opinion": 5,
+        "reason": "keeps trying to get other users to join the Dark Side, whatever that is"
+    }
+},
+```
+
+We expand the `enum` `recommendation` with a new value `m.opinion`. This value states that the
+policy states an opinion published by its issuer.
+
+We expand the `content` with a new field
+
+| Field     | Type | Description |
+|-----------|------|-------------|
+| `opinion` | Integer in [0, 100) | A subjective opinon on the behavior of the entity. A value of `0` represents an extremely poor opinion, while a value of `100` represents an extremely favorable opinion. |
+
+Tools are free to mix and match `opinion`s from different *sources that they trust* to come up with a
+decision on e.g. whether an entity should be allowed in a community.
+
+## Potential issues
+### Conflicting Opinions
+
+Two different communities may very well have very different opinions on an entity. That is
+actually not an issue but rather a feature. If these communities cannot trust each other's
+judgement, perhaps because they share different worldviews, they should not attempt to use
+each other's published opinions.
+
+
+### Malicious Gossip
+
+A malicious community Marvinites may use this mechanism to publish negative opinions on
+user Alice, attempting to poison the perception of Alice among the community of Bobites.
+
+As above, the solution to this is to realize that another Marvinites and Bobites have different
+opinions and that Bobites should not use the opinions published by Marvinites.
+
+
+### Accidental Snitching
+
+The community of Alicites may publish a positive opinion on users that they appreciate. If,
+however, the activities of Alicites are illegal in some regions, authorities may decide to
+use the opinions published by the Alicites to try and locate users friendly to Alicites.
+Similarly, a malicious group of Marvinites may use the opinions published by the Alicites
+and use it as a base for online bullying.
+
+The fact that apinions are stored and shared within Matrix rooms can help to some degree,
+as Matrix rooms may be configured to require invites. If Alicites and their sympathizers
+are in a position to be prosecuted or bullied, they may use this mechanism to restrict
+access to opinions to users that they trust sufficiently.
+
+Another consideration is that Alicites may need to restrict themselves to only publishing
+negative opinions, rather than both positive and negative opinions.
+
+
+### Thought Bubbles
+
+By subscribing to a community's opinion feed, a user may end up restricting their worldview
+to that of their community, as is already illustrated by a number of existing social networks.
+
+However, existing social networks typically create these bubbles through a form of black box
+analysis. By opposition, the mechanism of opinions can be audited. Further, tools can be built
+e.g. in Matrix clients to let users investigate the opinions they follow, tweak them,
+deactivate them.
+
+## Alternatives
+
+Alternative solutions have been proposed to combat online toxicity. However, these solutions
+typically require a large/complete loss of privacy.
+
+We expect that by decentralizing opinions and putting them in the hands of communities and
+individual users, we will help demonstrate that such proposals are unnecessary.
+
+## Unstable prefix
+
+During prototyping, `m.opinion` will be prefixed as `org.matrix.mscxxxx.opinion`.