How did Leibniz’s ideas anticipate machines that check logical deductions?

Gottfried Wilhelm Leibniz anticipated the development of machines capable of checking logical deductions through his proposal for a calculus ratiocinator, or "calculus of reason".12

Leibniz envisioned that by creating a formal symbolic logic, reasoning could be transformed into a process similar to arithmetic. In this system, symbols would represent concepts, and explicit rules would govern their manipulation. By following these rules, one could mechanically or algorithmically derive new truths or verify whether a proposed conclusion followed logically from a set of premises.12

Because this process would function like performing large sums, Leibniz realized it would be immune to human errors or failures of ingenuity. He explicitly contemplated the possibility that such logical derivations could be performed by machines constructed to draw valid inferences or check the deductions of others. This visionary concept was later pursued in the 19th century by figures such as Charles Babbage, William Stanley Jevons, and Charles Sanders Peirce, eventually finding broad success in the development of modern computers.12