Also, your assertion that to call a discipline a science, it needs to use the scientific method, is well... demonstrably false, simply by virtue of the fact that we are having this debate.
The scientific method produces very reliable knowledge, but it is not the only way to produce knowledge that is reliable. There is also knowledge that we rely on that is not as rock solid as knowledge obtained from the scientific method, but which is still valuable and still falls under the realm of science, because it is still part of the systematic pursuit of progressively more reliable knowledge.