Terms Governing Spare Key Uncertainty
The keychain has seven keys. Two open known locks. The other five are retained because their purpose is not remembered but might be important.
TERMS AND CONDITIONS GOVERNING RETAINED KEYS OF UNKNOWN PURPOSE
These terms govern the decision to retain a key whose corresponding lock is not currently identified.
Article 1: The Retention Standard
A key may be retained indefinitely if:
(a) Its purpose is unknown but cannot be confirmed as no longer applicable. (b) It was received as part of a set and removing it requires a decision that was not required at receipt. (c) It is small enough to add negligible weight to the keychain.
All three conditions are met by most keys of unknown purpose. Most keys of unknown purpose are therefore retained.
Article 2: The Disposal Threshold
A key may be disposed of only when:
(a) Its lock has been conclusively identified as no longer existing. (b) A positive identification of the lock is made and the lock is confirmed as irrelevant. (c) The keychain becomes large enough that its weight becomes a daily source of mild inconvenience.
Condition (a) requires information that is typically unavailable. Condition (b) requires testing the key in potential locks, which is an activity that has not been performed. Condition (c) is a threshold that is higher than it sounds.
Article 3: The Consequence Model
If a key is retained unnecessarily: a small weight remains on the keychain indefinitely. No other consequence.
If a key is disposed of and later found to be necessary: a situation occurs where a lock cannot be opened and the key is no longer available. This situation is theoretical but possible.
The consequence of unnecessary retention is small. The consequence of incorrect disposal is potentially significant. Retention is the rational choice.
Article 4: Duration
The key will be retained until the keychain is lost, the key is positively identified as unnecessary, or the household moves and the key sorting that accompanies a move produces an unusually direct decision-making process.
Until then: the key remains. It has always remained. It will continue to remain.