This is a preprint of an article whose final and definitive form will be published in the Australasian Journal of Philosophy 2014; the Australasian Journal of Philosophy is available online at: http://www.tandf.co.uk/journals/.Arguments from disagreement often take centre stage in debates between competing semantic theories. This paper explores the theoretical basis for arguments from disagreement and, in so doing, proposes methodological principles which allow us to distinguish between legitimate arguments from disagreement and dialectically ineffective arguments from disagreement. In the light of these principles I evaluate Cappelen & Hawthorne's (2009) argument from disagreement against relativism, and show that it fails to undermine relativism since it is dialectically ineffective. Nevertheless, I argue that an alternative challenge to relativism based on disagreement is available. More generally, I argue that semantic theory is not answerable to data stemming from 'loaded' philosophical principles regarding the nature of disagreement. Rather, semantic theorists will exhaust their dialectical responsibilities regarding disagreement if they can demonstrate consistency with a minimal account of the concept.Arguments from disagreement often play an influential role in debates between semantic theories.In the recent debate over relativism, for instance, arguments from disagreement have been variously taken to provide evidence either for or against different forms of semantic relativity in expressions such as taste predicates and epistemic modals. This paper explores an aspect of these arguments which has not yet received the attention it deserves: namely, the role of philosophical assumptions about the nature of disagreement in arguments from disagreement. I explore what an argument from disagreement may legitimately assume about disagreement's nature whilst remaining dialectically effective in a debate over semantic theory-that is, to establish what should be considered data to be accommodated by a successful semantic theory, and the extent to which substantive philosophical assumptions about disagreement can be considered part of this data. The aim is not only to establish methodological constraints on the use of arguments from disagreement in semantic theory, but also to shed light on how we should theorise about disagreement more generally. 1 1 I focus solely on the notion of disagreement as a state, rather than as an activity (Cappelen & Hawthorne (2009: 60-61)). A state of disagreement is most naturally understood as a passive concept, arising out of some conflict between subjects' attitudes, and not necessarily involving any active behavioural features such as the presence of a dispute. In the stative sense, two subjects might disagree (e.g. in virtue of inconsistency between their beliefs) even though neither subject is aware of the existence of the state.