Passage Summary: Proofs that rely on computers aren't as certain as things humans can double-check themselves, like basic math, because we can't personally verify the computer's work.

Reasoning: Computer-dependent proofs cannot be verified by human cognition alone, whereas simple mathematical facts can be, and this lack of human verification results in a lower level of certainty.

Analysis: The passage establishes a direct correlation between human verifiability and the degree of certainty a proof provides. Since computer-dependent proofs are defined as being beyond the reach of human cognition alone, they are inherently less certain than arithmetical facts. Look for an inference that confirms that any proof requiring a computer for its verification cannot reach the highest level of certainty available to human thought.