Anarchism is a political philosophy encompassing theories and attitudes which support the elimination of all forms of compulsory government[1]. The term anarchism derives from the Greek ἀναρχος, anarchos, meaning "without a leader, head or chief", from the prefix ἀν- (an-, "without") + ἄρχή (archê, "sovereignty, realm, magistracy") + -ισμός (-ismos, from a stem -ιζειν, -izein). It is defined by The Concise Oxford Dictionary of Politics as "the view that society can and should be organized without a coercive state." Specific anarchists may have additional criteria for what constitutes anarchism, and they often disagree with each other on what these criteria are. According to The Oxford Companion to Philosophy, "there is no single defining position that all anarchists hold, beyond their rejection of compulsory government, and those considered anarchists at best share a certain family resemblance".