Antinomy (Ancient Greek: antí 'against' + nómos 'law') refers to a real or apparent mutual incompatibility of two notions.
[2] Empirical reason cannot here play the role of establishing rational truths because it goes beyond possible experience and is applied to the sphere of that which transcends it.
Reason makes equal claim to each proof, since they are both correct, so the question of the limits of time must be regarded as meaningless.
These contradictions are inherent in reason when it is applied to the world as it is in itself, independently of any perception of it (this has to do with the distinction between phenomena and noumena).
Kant's goal in his critical philosophy was to identify what claims are and are not justified, and the antinomies are a particularly illustrative example of his larger project.