Subjectivism is the doctrine that "our own mental activity is the only unquestionable fact of our experience",[1] instead of shared or communal, and that there is no external or objective truth.
While Thomas Hobbes was an early proponent of subjectivism,[2][3] the success of this position is historically attributed to Descartes and his methodic doubt.
He used it as an epistemological tool to prove the opposite (an objective world of facts independent of one's own knowledge, ergo the "Father of Modern Philosophy" inasmuch as his views underlie a scientific worldview).
"[1] While Thomas Hobbes was an early proponent of subjectivism,[2][3] the success of this position is historically attributed to Descartes and his methodic doubt.
This has its philosophical basis in the writings of Descartes (see cogito ergo sum), and forms a cornerstone of Søren Kierkegaard's philosophy.
Giovanni Merlo has developed a specific version of metaphysical subjectivism, under which subjective facts always concern mental properties.
In this way, though, subjectivism morphs into a related doctrine, panpsychism, the belief that every objective entity (or event) has an inward or subjective aspect.
One implication of these beliefs is that, unlike the moral skeptic or the non-cognitivist, the subjectivist thinks that ethical sentences, while subjective, are nonetheless the kind of thing that can be true or false depending on situation.
[11] According to the objectivist view, the rules of Bayesian statistics can be justified by requirements of rationality and consistency and interpreted as an extension of logic.
To explain his meaning, de Finetti created a thought-experiment to illustrate the need for principles of coherency in making a probabilistic statement.