Kant presented four antinomies, each presented as a pair of thesis and antithesis. The first antinomy argues that the world does have a beginning in time. Kant supports this argument by stating that if we assume that the world has no beginning in time, then an infinite series of successive states of things would have passed away in the world. However, the infinity of a series implies that it can never be completed through successive synthesis, making it impossible for an infinite world-series to have passed away. Therefore, a beginning of the world is a necessary condition for the world's existence. Priest, in his book Beyond the Limits of Thought, challenges Kant's argument by appealing to set theory and stating that Kant's appeal to Aristotle's assertion that completed infinities do not exist doesn't hold. However, I disagree with Priest's argument. Set theory does have infinities, but they represent a new iteration towards the infinite without a completion. Additionally, set theory is conceptual, while time is a physical notion. When considering the infinite past in a physical way, it is impossible to assert that time past can be infinite because time must pass. While there could be an infinite number of worlds with their own notion of time, in our world with its own notion of time, time past must be finite. Is there a better argument as to why Kant's argument must fail? Or is Priest simply presenting the standard arguments? Or is the failure of this thesis actually beside the point, considering that Kant is working at the limits of what we can know?