If object a has property F, there must be an ontological explanation of why F and a are connected such that a has F as one of its properties (unless F is essential to a).
A typical line for those convinced that the regress is vicious has consisted in proposing that instantiation is not a relation, or at least not a normal one. Some philosophers hold that it is a sui generis linkage that hooks things up without intermediaries. Peter Strawson (1959) calls it a non-relational tie and Bergmann (1960) calls it a nexus. Broad (1933: 85) likened instantiation to glue, which just sticks two sheets of paper together, without needing anything additional; similarly, instant