 Next, Armstrong's investigations into the metaphysics of properties (in, e.g., his 1978a,b, 1989, 1997, and 2010) are notable, first, in treating determination as an explicitly metaphysical relation, and second, in raising to salience the important question of whether determinables are ontologically reducible to determinates, asked against the commonly accepted background assumption that reality itself is maximally determinate. As we’ll see, Armstrong’s own position on this score swings from reductionism (1987) to non-reductionism (1997), and back again (2010).