There is no one answer. You might start by a knowledge of nomenclature and terminology. Be aware of the difference between the philosophical, scientific, and mathematical methods and the purpose and function of each method. Be aware that they are not interchangeable. Establish some proficiency in science and the scientific method. Read the hundred years of opinion concerning change before Darwin. Then read all of Darwin's work and then the 150 years of evidence since then. However there is at least three observed new species cited on this very thread. That you choose to ignore them is by your own opinion.
"..three observed new species cited on this very thread."
Please point me to at least one, and I'll check it out in a day or two.
Keep in mind, that subspecies is DIFFERENT from species.
'night everybody.