 Presentists and eternalists make competing claims about temporal ontology. According to presentism, only present things exist. According to eternalism, past and future things, such as dinosaurs and human outposts on Mars, exist as well. These are theories about what there is, just like actualism, possibilism, Platonism, nominalism, Meinongianism, idealism, materialism, theism, atheism… (2006: 75)