Display an author’s posts on his own author page

You can simply use the default author.php page to do this. If you don’t have one, make a copy of index.php and rename it author.php

Now, use pre_get_posts to include your custom post type in the author pages. This code goes in functions.php

function cpt_on_author_page( $query ) {
    if ( !is_admin() && $query->is_author() && $query->is_main_query() ) {
        $query->set( 'post_type', array( 'post', 'philosopher' ) );
        $query->set( 'posts_per_page', 10 );
    }
}
add_action( 'pre_get_posts', 'cpt_on_author_page' );