 The first premise is supported by the Consequence Argument (see entry on  arguments for incompatibilism §5):  Given determinism, Kurt’s theft was a necessary consequence of the distant past plus the laws of nature. Kurt has no power over either of these, so he couldn’t avoid stealing John’s lunch. The second premise is an instance of PAP. And the conclusion can be generalized to apply to any action: if determinism is true, no one is responsible for anything they do.