First speakers should first give a brief introduction, contextualising the debate, and perhaps exploring the basic philosophical questions raised by the topic. Ordinarily, the first affirmative speaker would then explain the affirmative team's 'model', or 'mechanism'. It is not enough for a team simply to argue that we should implement some policy. The team must also explain to us how the policy is going to be implemented. That explanation is the 'model'. The first negative speaker can also use a 'model', often called a 'counter-model', but would only do so in particular circumstances. The first negative speaker should always make some points in rebuttal at this stage of the speech. However, such rebuttal should be kept short.