  We are of the opinion that several anomalies in the atmosphere of Venus
provide evidence of yet-unknown processes and systems that are out of
equilibrium. The investigation of these anomalies on Venus should be open to
the wide range of explanations, including unknown biological activity. We
provide an overview of two anomalies, the tentative detection of ammonia and
phosphine in Venus's atmosphere. These anomalies fly in the face of the tacit
assumption that the atmosphere of Venus must be in chemical redox equilibrium,
an assumption connected to the belief that Venus is lifeless. We then discuss
several major past discoveries in astronomy, biology and geology, which lead to
the abandonment of certain assumptions held by many scientists as though they
were well-established principles. The anomalies of ammonia and phosphine in the
atmosphere of Venus are placed in the context of these historical discoveries.
This context supports our opinion that persistence by the community in the
exploration of these anomalies with a skeptical eye towards tacit assumptions
will increase the chances of making profound discoveries about the atmosphere
of Venus and the diverse and often strange nature of planetary environments.
