Don't confuse contingency with arbitrariness.
And don't think that contingency means that we can not commit ourselves to priorities in regard to functionality of the sign, the concept, the phenomenon – or that everything might/will change just in the moment we change its label or characterization.
A mouse will not grow wings just because we want it so. Gravitation will not vanish because we abandon the model.
Contingency comes with context. One context of contingency is functional equivalence. For example: when we want to heat our homes, fossil oil is functional equivalent to solar energy, but when it comes to matters of environmental pollution there are many application areas including the warmth of our homes where we should consider solar energy the more sensible choice.
Context matters. Perspectives matter. Functionality matters.
Contingency should not become a thought-terminating cliché.