Question

Question #52e07

Answer 1

Because Price is a reflection

According to Smith's classique theory of The Hidden Hand, There are Two directions of the Pandolin effect to reach Equilibrium, in both directions Price Acts as a reflection to the Driving Force,

When Quantity Supplied is the Independent variable (Driving Force), price is the dependent variable. But price (acting as a reflection to Quantity Supplied) will transfers the effect into the Quantity Demanded and vise versa.
i.e.:
at Surplus condition: Decreasing Supply (negative delta) due to Suppliers exiting market (independent decision) will decrease price (we are moving down the supply slope). the new price will attract Quantity demanded, so Qd is actually affected by Qs which is on the same horizontal Access.

While at deficit condition: The High demand will encourage Suppliers to increase Qs (positive delta) and the price (encouraged by high demand) then will increase, hence, Price increase will affect the Quantity Demanded negatively.

Now Remember that the Classique believed that Supply Generates Demand (not proved wrong until Keynes), The Bottom Line is:
Qs increase will increase P which will Decrease Qd
Qs Decrease will Decrease P which will Increase Qd

So P Reflects Qs (Classique's Independent Variable) and, Hence, Controls Qd (Classique's Dependent Variable)