In any case, pitch stability requires that the lift slope of the canard wing is lower than the lift slope of the main wing: to achieve stability, the change in lift coefficient with angle of attack should be less than that for the main plane.
In any case, pitch stability requires that the lift generated by the canard wing is significant, so in order to minimise induced drag on the canard, it is usually of higher aspect ratio and greater airfoil camber than a control-canard. To achieve stability, the change in lift coefficient with angle of attack should be less than that for the main plane.