What was the name of the Logician that had defined the specific kind of symbolic logic choosen?

The logician who is primarily associated with the development of symbolic logic is Gottlob Frege. Frege is often considered the father of modern logic and his work laid the foundation for much of the symbolic logic that followed. He introduced a formal system that distinguished between the structure of arguments and the content of statements, allowing for clearer analysis of logical relationships.

Frege's most notable contributions include his concept of quantifiers and his work on the logic of propositions. His book, "Begriffsschrift," published in 1879, presented a new symbolic language for logic, which represented the relationships between terms and laid the groundwork for later developments in logical theory. Other notable figures in the realm of symbolic logic include Bertrand Russell and Alfred North Whitehead, who further expanded upon Frege's ideas in their work "Principia Mathematica."