  This influential line of argument leads directly to PSA, and thence to the associated Retentional model of temporal consciousness. Although the difficulty may seem serious, the Extensional theorist has an effective line of reply: the argument in question can be seen as simply begging the question. Recall the way in which the Extensional theorist construes an individual specious present, as depicted in Figures 5 and 6: a single specious present is viewed as a temporal spread of contents that are all experienced together, i.e., that are diachronically co-conscious. Right at the heart of the Extensional model is an assumption concerning the nature of phenomenal unity. The assumption is precisely that phenomenal unity is not confined to contents that are momentary and simultaneous, it can embrace contents that are spread (a short distance) through time. Accordingly, provided the envisaged succession of phases [P1, P2, P3 … Pn] are related in this manner – they are diachronically co-conscious, and so are experienced together – they already constitute an experience of succession, and nothing further is required. Now it could be that the Extensional theorists are misguided in making this assumption: perhaps phenomenal unity cannot extend over time in the way they claim. But since the line of argument set out in the previous paragraph simply ignores the mode of phenomenal unity posited by Extensional model theorists, it fails to provide us with any reason for thinking this is the case. In effect, the objection presupposes that that synchronic phenomenal unity – the sort of unity which obtains among simultaneous momentary contents – is the only mode of phenomenal unity.