The Lucas critique is an economic theory proposed by economist Robert Lucas in the 1970s. It argues that traditional economic models can be misleading when evaluating the effects of policy changes. This is because these models often assume that people's expectations remain constant, ignoring how individuals adjust their behavior in response to new policies. According to the critique, if policymakers do not consider how expectations change, their predictions about the economy may be inaccurate. This means that effective economic policy must account for the way people adapt their decisions based on anticipated outcomes, making it essential to incorporate expectations into economic models.