A demonstration that "unscoped" just clobbers everything in the scope chain

output.txt

-- create_table(:posts)
   -> 0.0189s
-- create_table(:comments)
   -> 0.0005s
4.0.1
SELECT "comments".* FROM "comments"  WHERE "comments"."post_id" = ?  ORDER BY comments.id desc
SELECT "comments".* FROM "comments"
SELECT "comments".* FROM "comments"

unscoped.rb

gem "rails", "~> 4.0.0"

require "active_record"
require "logger"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
# ActiveRecord::Base.logger = Logger.new(STDERR)

ActiveRecord::Schema.define do
  create_table :posts

  create_table :comments do |t|
    t.integer :post_id
  end
end

class Comment < ActiveRecord::Base
  default_scope { order "comments.id desc" }
end

class Post < ActiveRecord::Base
  has_many :comments
end

puts ActiveRecord::VERSION::STRING

post = Post.create

puts post.comments.to_sql
puts post.comments.unscoped.to_sql
puts Comment.order("omg").where("wtf").unscoped.to_sql