Posthumanism in a futurist context incorporates a number of different meanings.
Posthumanism has multiple unrelated and overlapping definitions and is generally a confusing term.
As a critique of humanism
Posthumanism is often a critique of humanism especially in the context of human exceptionalism, sometimes known as antihumanism.
Humanism, subjective relativism, is fundamentally based on the notion that: "The man is the measure of everything" (Protagoras), and posthumanism critiques this inherent human exceptionalism. Transhumanism is a part of Posthumanism, as Transhumanism specifies that humanity and human condition are defined by the technological context, so the "measure" mentioned by Protagoras changes in time. This binds the transhumanism idea into the continuation of the philosophical humanist tradition. In Wikipedia, this definition is called: "Philosophical Posthumanism".
Beyond humanity as we know it
Examples of futurist posthumanism that doesn't address the human condition explicitly are:
- Space seeding advocates
- Bioethical abolitionists
- Transanimists - advocates of spreading life throughout the universe
- Animal enhancement advocates
As a developed form of transhumanism
Posthuman transhumanism can incorporate both 'what comes after' humanity and transhumanism, however is often used synonymously with mainstream transhumanist philosophies in highly futuristic scenarios.