Sparks's supposition makes sense if you assume that the natural state of humanity is evil, or zero good. From that standpoint good is always a positive element, and evil is the default. Of course, not everyone would agree with that assumption. Personally, I believe that it takes intention and (strange as it sounds) dedication to be truly maximally evil, if such a thing exists.
Now, you can assign whatever point of reference you want, but there's one important aspect about the two comparisons he makes that drives one half of the balance being considered the active half: one side is bounded, the other unbounded. There is a maximum dark you can have, an absolute zero of temperature, but no maximum light or heat, because these two scales bottom out at not having any of the active element. For the same to be true of good, there must be a limit on how evil you can be, but not on how good. Is that true? Maybe. But again it's not a good assumption to make without some better basis.
Interestingly, Sparks's introduction of God undercuts his argument by setting an upper boundary on good. You can't be more good than God, so at best good and evil become equally good measures of humans (presuming a devil to represent maximum evil), and at worst evil is unbounded and good must be its absence.
(no subject)
Now, you can assign whatever point of reference you want, but there's one important aspect about the two comparisons he makes that drives one half of the balance being considered the active half: one side is bounded, the other unbounded. There is a maximum dark you can have, an absolute zero of temperature, but no maximum light or heat, because these two scales bottom out at not having any of the active element. For the same to be true of good, there must be a limit on how evil you can be, but not on how good. Is that true? Maybe. But again it's not a good assumption to make without some better basis.
Interestingly, Sparks's introduction of God undercuts his argument by setting an upper boundary on good. You can't be more good than God, so at best good and evil become equally good measures of humans (presuming a devil to represent maximum evil), and at worst evil is unbounded and good must be its absence.