Drake Equation

The reason why the Drake Equation is not a successful science is because it would be impossible to calculate some of the elements in the equation. The elements would take too long to get an accurate sample to give a scientifically sound explanation.

For instance how would you calculate fi (the fraction of intelligent life forms), how do you define intelligent? Is intelligent like you and I, is it like a bird or a rat, could it be a plant? There is no way to truly determine what counts and doesn't count as intelligent life forms. There is too much gray area!

Another element to the equation is fc, (the fraction of intelligent species that develop interstellar communication). How would we know which species developed interstellar communication? It would take too long to get out to the life form and then get back to Earth. Once we get out to the life forms how do we know that these certain life forms created the interstellar communication