Why do political parties present vague positions? We suggest that voter polarization provides them incentives to present either clear or vague positions, and the choice between these two is determined by the priority of an issue for the parties. We find that facing voter polarization, Western European political parties present clearer positions on an issue when it is a prime issue for them, but blur their positions when it is a secondary issue. Then, position blurring gives different implications to party systems with different degrees of issue dimensionality (such as American vs Western European party systems). The results also imply that political parties will respond to ongoing voter polarization on economic and immigration issues differently in the clarity of their position.
