A reason for the emergence of Chebyshev's bias is investigated. The Deep
Riemann Hypothesis (DRH) enables us to reveal that the bias is a natural
phenomenon for making a well-balanced disposition of the whole sequence of
primes, in the sense that the Euler product converges at the center. By means
of a weighted counting function of primes, we succeed in expressing magnitudes
of the deflection by a certain asymptotic formula under the assumption of DRH,
which gives a new formulation of Chebyshev's bias.
For any Galois extension of global fields and for any element σ in the
Galois group, we establish a criterion of the bias of primes whose Frobenius
elements are equal to σ under the assumption of DRH. As an application
we obtain a bias toward non-splitting and non-principle primes in abelian
extensions under DRH. In positive characteristic cases, DRH is proved, and all
these results hold unconditionally