Fierz makes some remarks on some recent papers about weak interactions.

Symanzik replies to two points raised by Pauli : 1) The selection rule, 2) The isotope problem.

Fierz sends some corrections to a first letter he had written on the same day (see letter fierz_0016-283r).

Fierz replies to a letter by Pauli and makes some remarks on the $\beta$-decay. Fierz sent another letter on the same day including some corrections to this one (see letter fierz_0016-282r).

Fierz makes further remarks concerning a paper by Stückelberg.

Pauli discusses the philosophical duality realism-nominalism. He mentions that he is one of those who think that ideas have a reality at least as strong as that of sensations.