What WP-API authentication method should I use to interact with anonymous / not-logged visitors?

In WP REST API v2 use the permission_callback found in the Adding Custom Endpoints Docs.

<?php
add_action( 'rest_api_init', function () {
    register_rest_route( 'myplugin/v2', '/author/(?P<id>\d+)', array(
        'methods' => 'GET',
        'callback' => 'my_awesome_func',
        'args' => array(
            'id' => array(
                'validate_callback' => 'is_numeric'
            ),
        ),
        'permission_callback' => function (WP_REST_Request $request) {
            if ( current_user_can( 'edit_others_posts' ) ) {
                return true;
            } 
            else { 
                return false;
            }
        }
    ) );
} );