Subjectivism

Subjectivism is a philosophical tenet that accords primacy to subjective experiences. In an extreme form, it may hold that the nature and existence of every object depends only on someone's subjective awareness of it. One may consider the qualified empiricism of George Berkeley in this context, given his reliance on God as the prime mover of human perception.

Metaphysical subjectivism
Metaphysical subjectivism is the theory that perception creates reality, and that there is no underlying, true reality that exists independent of perception. One can also hold that it is consciousness rather than perception that creates reality. This is in contrast to metaphysical objectivism, which asserts that there is an objective reality which is perceived in different ways.

This holding should not be confused with the stance that "all is illusion" or that "there is no such thing as reality." Metaphysical subjectivists hold that reality is real enough, and that physical objects do exist. They conceive, however, that the nature of reality as related to a given consciousness unit is created and governed by that consciousness.

Subjectivism and panpsychism
One possible extension of subjectivist thought is that conscious experience is available to all objectively perceivable substrates. Upon viewing images produced by a camera on the rocking side of an erupting volcano, one might suppose that their relative motion followed from a subjective conscious within the volcano. These properties might also be attributed to the camera or its various components as well.

In this way, though, subjectivism morphs into a related doctrine, panpsychism, the view that every objective fact has an inward or subjective aspect.

Criticisms
The invention of machines that can "see", "hear", or otherwise observe and record events provoked a thought experiment (offered by Winston Churchill, who is not otherwise known as a philosopher) that has created difficulties for subjectivists. Let us set up an automatic camera to record events in a place that no human (or other creature reasonably considered "conscious") can observe. Say that it is set inside a volcano, for example. The camera is later retrieved and its photographs, with date markings, are observed. Did the events recorded in the photographs really happen even though no one consciously observed them? Did the conscious observation of the photographs themselves somehow suddenly cause them to depict events that apparently happened at an earlier time?

One explanation of this scenario from a subjectivist perspective is that the events in the photographs didn't really happen at all. Only the photographs came into existence as the observer went to collect the results of their test.

This explanation fails to explain why the pictures would exist to be collected if they were not objectively present to be collected in the first place.

Ethical subjectivism
Ethical subjectivism is the meta-ethical view that ethical sentences reduce to factual statements about the attitudes and/or conventions of individual people. An ethical subjectivist might propose, for example, that what it means for something to be morally right is just for it to be approved of. (This can lead to the view that different things are right according to each idiosyncratic moral outlook.) Another kind of ethical subjectivist might define "good" as "that which I desire".

A related view is that of conventionalism, which considers ethical sentences to be representations of the attitudes of a number of persons in a culture or society.

One implication of these views is that, unlike the moral skeptic or the non-cognitivist, the subjectivist thinks that ethical sentences, while relative or subjective, are nonetheless the kind of thing that can be true or false.

Subjectivism in probability
In probability, a subjectivism stands for the view that probabilities are simply degrees-of-belief by rational agents in a certain proposition, and which have no objective reality in and of themselves. For this kind of subjectivist, a phrase having to do with probability simply asserts the degree to which the subjective actor believes their assertion is true or false. As a consequence, a subjectivist has no problem with differing people giving different probabilities to an uncertain proposition, and all being correct. See Bayesianism.

In attempting to justify subjective probability, Bruno de Finetti created the notion of philosophical coherence. According to his theory, a probability assertion is akin to a bet, and a bet is coherent only if it does not expose the wagerer to loss if their opponent chooses wisely. To explain his meaning, de Finetti created a thought-experiment to illustrate the need for principles of coherency in making a probabilistic statement. In his scenario, when someone states their degree-of-belief in something, one places a small bet for or against that belief and specifies the odds, with the understanding that the other party to the bet may then decide which side of the bet to take. Thus, if Bob specifies 3-to-1 odds against a proposition A, his opponent Joe may then choose whether to require Bob to risk $1 in order to win $3 if proposition A is found to be true, or to require Bob to risk $3 in order to win $1 if the proposition A is not true. In this case, it is possible for Joe to win over Bob. According to de Finetti, then, this case is incoherent.