replacement - Table doesn't replace inside conditionals (If, Which)

This:

Table[If[cond, y], {y, 1, 3}]

outputs this:

{If[cond, y], If[cond, y], If[cond, y]}

The y is not replaced by its value, as is normally the case with Table[]. This also happens with Which[].

How do I get Table to actually replace the values for y? Why does this happen?