Now with all guys that have a girlfriend or wife, we can make a general assumption that for all species of the female sex (F), Time (T) and money($) are required for any major conquest or pacification.

As such we can infer the initial mathematical relation that:

Girls = Time x Money ------- (1)

Next we further exert the natural and common agreement that time is money,

Time = Money ------------------------ (2)

Therefore by combining Equation (1) and (2) we can derive that,

Girls = Time x Money

= Money x Money

= Money ^ 2

So we get equation 3,

Girls = Money ^ 2 --------- (3)

Further to this, we also know that Money is the root of all Evil, which generalizes evil, and from that we can write the identity:

Money = Evil ^ (1/2) ----------- (4)

Thus taking equation 3 and 4 and combinding them, we get

Girls = Money ^ 2

= (Evil ^(1/2))^2

= Evil

Thus, by mathematical proof and the above proposition, we are forced to conclude that mathematically, Girls are Evil.