You state that "philosophy is a science." I understand you are not a native English speaker. Well, I am an English teacher, so please hear me out.

The word "a" is called the indefinite article. And if you use the word "a" to describe a noun, you are implying that the noun can be pluralized.

A boat. Boats. A cat. Cats. A man. Men.

A science. Sciences.

So when you say that "there is no plural to a science," you are contradicting yourself.

The reality is that in English the word science can be a count or non-count noun. Biology is a science. Physics is a science. Biology and physics are sciences. And if you are talking about the entire world of science, you can use science as a non-count noun.

Math is different. In America we say math, non-count noun. In England they says maths, count noun. Who is right? Both and neither.

Because there's also a science called linguistics. And within that science are the ideas of prescriptive linguistics and descriptive linguistics. Prescriptive linguistics is rule based and tries to enforce language rules. Descriptive linguistics just tries to describe how people actually use language.

In your post, you are being prescriptive. You are trying to tell people how they should use language. You have a right to do this. But according to the observations of descriptive linguistics, most people aren't going to follow your advice.

So, you might want to get over it. There is philosophy, the classical method of attempting to arrive at truth through logic. This is often referred to as philosophy, non-count. But then there are the countless other methods of trying to find truth, and we as English speakers have collectively decided to call them philosophies. The very fact that the autocorrect on my iPhone didn't try to change the spelling of philosophies attests to this fact.

People talks how they wants ta talks. Attempting to understand their meaning in spite of their misuse of words, whether real or perceived, is a beneficial exercise. This is my philosophy.