Here’s how Calian can fill in the blanks in his argument:
Any positive number raised to the power 1 is equal to itself. Written as an equation, this means that $$ b^1 = b $$ for any positive base. This equation is equivalent to the logarithmic equation $$ \log_b b = 1 $$. Therefore, it must be true that logb b=1 for any positive base that is not equal to 1.