Blue or White?

On our talleisim (for most of us) there are 8 white threads on each corner. Some talleisim have some blue threads. Seemingly, we should all have these blue threads as the Torah tells us to place blue (techeiles) thread (15:38). Why then do we not do this?

This blue colour was derived from a worm call the chilazon. We have lost the tradition for this worm. However, some claim (with proofs) that they have identified the chilazon and produce the techeiles. If so, we should all be stringent and have techeiles. Even if it is incorrect, seemingly, it does not harm. So why do we not all wear talleisim with techeiles?

Many different answers are suggested. There are some opinions (Rashi, Rambam) that the colour of the threads should be the same colour as the corner of the garment of clothing, the only exception being real techeiles. If the garment is blue the threads should be blue. If green, the threads should be green. Our talleism are white and so to fulfill the mitzvah of tzitzis, white threads are required (and real techeiles if there is). Therefore if the new found chilazon is not the real deal, the mitzvah is not being performed and there is in fact harm. (R’ Chaim Solovetzik – quoted)

Anther answer that is suggested is that when it comes to questions and clarification regarding laws, then we consult the sages and their proofs, but when it comes to questions and uncertainties regarding the existence and identification of something, we do not rely on proofs, rather we rely on the tradition given to us by our fathers and their fathers. Since we have lost the tradition regarding the identification of the chilazon and the techeiles, proofs do not help. (Beis HaLevi – quoted)