The first phase runs approximately from 1900 to 1910.
It is characterized by the quasi-Platonic form of realism initially endorsed by Moore and Russell as an alternative to Idealism.
Many would also include Gottlob Frege as a founder of analytic philosophy in the late 19th century, and this controversial issue is discussed in section 2c.
When Moore and Russell articulated their alternative to Idealism, they used a linguistic idiom, frequently basing their arguments on the “meanings” of terms and propositions.
Their realism was expressed and defended in the idiom of “propositions” and “meanings,” so it was taken to involve a turn toward language.