| Importantly, indexicality does not imply non-rigidity. |
| Action signs, like vocal signs also take part in deictic reference, indexicality and performativity. |
| In the past, deixis was associated specifically with spatiotemporal reference whereas indexicality was used more broadly. |
| Indexicality should be distinguished from ambiguity. |
| By contrast, human actions must necessarily be guided by reference to the past, present or the future time, and so the indexicality of the A-series view of time is necessary. |
| The theories of Kripke, Soames, and the proposal of Devitt and Sterelny, among others, take a stand on how the indexicality of natural kind terms is implemented. |
