There is no accounting principle that keeps the gains from being reported. The principle of conservatism has to do with uncertainty. When uncertainty is reported between the two alternatives, accountant should pick the one that reports fewer profits and less assets amount i.e. the one with higher liability. This is different when there is uncertainty that reports a gain. It is imperative therefore, not to record the gain. The result of not recording the potential gain would be less assets amount and less profits amount.
The conviction of gain is reported. Example is when the company dispose an old asset for cash and the amount received is greater than the book value, then in this case there is certainty and a gain is recorded. Whether there is uncertainty about losses or not, the rule requires that everything is recorded. Through recording potential loss, the company will be reporting less profit and less assets amount. I think there should be accounting principle that requires the uncertain gain to be reported to ensure the possible increase in value is recorded.
This is true that gains and liabilities should be treated same way. You need to recognize gain when earned and liabilities when incurred. Gains can be recognized as unearned once you are certain. Liabilities are known once the costs are incurred.
A contingent liability is a potential one in essence. It rests on future events happening sooner or later. In accounting, the contingent liabilities are recorded with a journal entry only if the contingent is both probable and estimation of amount is possible. If contingent liability is only possible (not probable), then the amount becomes difficult to estimate and therefore journal entries is not required. When contingent liability is remote then no entries required i.e. any disclosure or journal entries are required.