possibilist

noun possibilists

1. Someone who advocates possibilism, the position that things do not need to actually exist in order to have properties. Unless the actualist can adduce reasons to believe an explanation for @’s actuality, therefore, she will be at a disadvantage to the possibilist who believes all worlds to be on metaphysical par.
2. historical A socialist who advocates focusing on small, achievable forms of immediate progress rather than an all-or-nothing commitment to revolution. As early as 1881, the possibilists had won considerable backing in Parisian municipal elections;
3. Someone who neither hopes without reason, nor fears without reason. Someone who uses analysis of data to understand the relative probability of future possibilities, instead of relying on intuition, emotions, personal experience, dogma, superstition, mainstream thought, or mental models (e.g., pessimism or optimism). People often call me an optimist, because I show them the enormous progress they didn't know about. That makes me angry. I'm not an optimist. That makes me sound naive. I'm a very serious “possibilist”. That’s something I made up. It means someone who neither hopes without reason, nor fears without

Opposite: actualist, antonym(s) of