We use the cobordism distance on the smooth knot concordance group
$\mathcal {C}$ to measure how close two knots are to being linearly dependent. Our measure,
$\Delta (\mathcal {K}, \mathcal {J})$, is built by minimizing the cobordism distance between all pairs of knots,
$\mathcal {K}'$ and
$\mathcal {J}'$, in cyclic subgroups containing
$\mathcal {K}$ and
$\mathcal {J}$. When made precise, this leads to the definition of the projective space of the concordance group,
${\mathbb P}(\mathcal {C})$, upon which
$\Delta $ defines an integer-valued metric. We explore basic properties of
${\mathbb P}(\mathcal {C})$ by using torus knots
$T_{2,2k+1}$. Twist knots are used to demonstrate that the natural simplicial complex
$\overline {({\mathbb P}(\mathcal {C}), \Delta )}$ associated with the metric space
${\mathbb P}(\mathcal {C})$ is infinite-dimensional.