Why are women in general not relied upon for eydus. Do we assume that they dont have the mental capacity to testify as some esxplain we dont rely on women to paskin by a safek...what about women pasul them from testiying. Especially since the gemarah has mentioned earlier that acc to some a special binah yeseira was given to women so why dont we accept thier eidus. Is it that they are not smart enough or that we just dont trust them? and if you'll say that we only use them when certian ones can be trusted... how could they only trust certian ones? how could we rely on certian women but not others...isnt that the same thing as nasata divarecha l'shuiyrun...ie that the law is diff depending on the person?
The reason why women in general are not valid witnesses has nothing to do with their mental capacity, and has nothing to do with their trustworthiness.
It is a Gezeiras ha'Kasuv, a law of the Torah, not necessarily based on any rational reason that we can comprehend (although, as I will mention soon, the Mefarshim do offer reasons).
It is not different from other forms of invalid witnesses. One example mentioned by Chazal is Moshe Rabeinu and Aharon ha'Kohen. If Moshe Rabeinu and Aharon ha'Kohen were to come as two witnesses to testify together about a certain event, their testimony would not be accepted. Why not? Is it because Moshe Rabeinu does not have the mental capacity? Is it because Aharon is not trusted? Obviously that is not the reason. Rather, it is a Gezeiras ha'Kasuv that two brothers testifying together are invalid. Similarly, a boy who is 12 years and 353 days old on Monday cannot testify, but on Tuesday morning he can.
Some commentators explain the specific Pesul of Edus of an Ishah as follows. Testimony, by definition, is done in a public setting, with judges, litigants, other witnesses, etc. The Pasuk says "Kol Kevodah Bas Melech Penimah," the grandeur of the Jewish woman is "inside," meaning that the woman's Avodah Hash-m is not done through public displays, but rather in private, in a manner of modesty. Her place is not out in the public courtroom, but rather in the home, building the foundation that is vital to the perpetuity of Hash-m's holy nation. The Torah recognized that to accept women's testimony in court would potentially lead to the breakdown of the foundation of the Jewish people -- i.e. the Jewish home and family -- and thus the Torah says that only men may testify in court.