 Loke (2017: 55–61; see Craig and Sinclair, 2009: 105–6) replies to the above objections by arguing that what is mathematically possible is not always metaphysically possible. For example, the quadratic equation \(x^2=4\) can have two mathematically consistent results for \(x\): 2 or −2, but if the question is “how many people carried the box home”, the answer cannot be −2, for in the concrete world it is metaphysically impossible that −2 people carry a box home. Thus, the conclusion of 2 people rather than −2 people derives not from mathematical equations alone but also from metaphysical considerations. Loke proceeds to argue that concrete infinities violate metaphysically necessary truths concerning causal powers. 