In art, essentialism is the idea that each medium has its own particular strengths and weaknesses, contingent on its mode of communication. A chase scene, for example, may be appropriate for motion pictures, but poorly realized in poetry, because the essential components of the poetic medium are ill suited to convey the information of a chase scene. This idea may be further refined, and it may be said that the haiku is a poor vehicle for describing a lover's affection, as opposed to the sonnet. Essentialism is attractive to artists, because it not only delineates the role of art and media, but also prescribes a method for evaluating art (quality correlates to the degree of organic form). However, considerable criticism has been leveled at essentialism, which has been unable to formally define organic form or for that matter, medium. What, after all, is the medium of poetry? If it is language, how is this distinct from the medium of prose fiction? Is the distinction really a distinction in medium or genre? Questions about organic form, its definition, and its role in art remain controversial. Generally, working artists accept some form of the concept of organic form, whereas philosophers have tended to regard it as vague and irrelevant.
This problem originally arose from the practice rather than theory of art. Marcel Duchamp, in the 20th century, challenged conventional notions of what "art" is, placing ordinary objects in galleries to prove that the context rather than content of an art piece determines what art is. In music, JohnCage followed up on Duchamp's ideas, asserting that the term "music" applied simply to the sounds heard within a fixed interval of time.
While it is easy to dismiss these assertions, further investigationshows that Duchamp and Cage are not so easily disproved. For example, if a pianist plays a Chopin etude, but his finger slips missing one note, is it still the Chopin etude or a new piece of music entirely? Most people would agree that it is still a Chopin etude (albeit with a missing note), which brings into play the Sorites paradox, mentioned below. If one accepts that this is not a fundamentally changed work of music, however, is one implicitly agreeing with Cage that it is merely the duration and context of musical performance, rather than the precise content, which determines what music is? Hence, the question is what the criteria for art objects are and whether these criteria are entirely context-dependent.
Philosophy of language.
A counterfactual statement is a conditional statement with a false antecedent. For example, the statement "If Joseph Swan had not invented the modern incandescent light bulb, then someone else would have invented it anyway" is a counterfactual, because in fact, Joseph Swan invented the modern incandescent light bulb. The most immediate task concerning counterfactuals is that of explaining their truth-conditions. As a start, one might assert that background information is assumed when stating and interpreting counterfactual conditionals and that this background information is just every true statement about the world as it is (pre-counterfactual). In the case of the Swan statement, we have certain trends in the history of technology, the utility of artificial light, the discovery of electricity, and so on. We quickly encounter an error with this initial account: among the true statements will be "Joseph Swan did invent the modern incandescent light bulb." From the conjunction of this statement (call it "S") and the antecedent of the counterfactual ("¬S"), we can derive any conclusion, and we have the unwelcome result that any statement follows from any counterfactual (see the principle of explosion). Nelson Goodman takes up this and related issues in his seminal Fact, Fiction, and Forecast; and David Lewis's influential articulation of possible world theory is popularly applied in efforts to solve it.
Epistemologicalproblems are concerned with the nature, scope and limitations of knowledge. Epistemology may also be described as the study of knowledge.
Plato suggests, in his Theaetetus (210a) and Meno (97a–98b), that "knowledge" may be defined as justified true belief. For over two millennia, this definition of knowledge has been reinforced and accepted by subsequent philosophers. An item of information's justifiability, truth, and belief have been seen as the necessary and sufficient conditions for knowledge.
In 1963, however, Edmund Gettier published an article in the periodical Analysis entitled "Is Justified True Belief Knowledge?", offering instances of justified true belief that do not conform to the generally understood meaning of "knowledge." Gettier's examples hinged on instances of epistemic luck: cases where a person appears to have sound evidence for a proposition, and that proposition is in fact true, but the apparent evidence is not causally related to the proposition's truth.
In response to Gettier's article, numerous philosophers have offered modified criteria for "knowledge." There is no general consensus to adopt any of the modified definitions yet proposed. Finally, if infallibilism is true, that would seem to definitively solve the Gettier problem for good--the idea is that knowledge requires certainty, such that, certainty is what serves to bridge the gap so that we arrive at knowledge, which means we would have an adequate definition of knowledge. However, infallibilism is rejected by the overwhelming majority of philosophers/epistemologists, even though it would solve the Gettier problem (if true).
Problem of the criterion
Overlooking for a moment the complications posed by Gettier problems, philosophy has essentially continued to operate on the principle that knowledge is justified true belief. The obvious question that this definition entails is how one can know whether one's justification is sound. One must therefore provide a justification for the justification. That justification itself requires justification, and the questioning continues interminably.
The conclusion is that no one can truly have knowledge of anything, since it is, due to this infinite regression, impossible to satisfy the justification element. In practice, this has caused little concern to philosophers, since the demarcation between a reasonably exhaustive investigation and superfluous investigation is usually clear.
Others argue for forms of coherentist systems, e.g. Susan Haack. Recent work by Peter D. Klein views knowledge as essentially defeasible. Therefore, an infinite regress is unproblematic, since any known fact may be overthrown on sufficiently in-depth investigation.
The Molyneux problem dates back to the following question posed by William Molyneux to John Locke in the 17th century: if a man born blind, and able to distinguish by touch between a cube and a globe, were made to see, could he now tell by sight which was the cube and which the globe, before he touched them? The problem raises fundamental issues in epistemology and the philosophy of mind, and was widely discussed after Locke included it in the second edition of his Essay Concerning Human Understanding.
A similar problem was also addressed earlier in the 12th century by Ibn Tufail (Abubacer), in his philosophical novel, Hayy ibn Yaqdhan (Philosophus Autodidactus). His version of the problem, however, dealt mainly with colors rather than shapes.
Modern science may now have the tools necessary to test this problem in controlled environments. The resolution of this problem is in some sense provided by the study of human subjects who gain vision after extended congenital blindness. One such subject took approximately a year to recognize most household objects purely by sight. This indicates that this may no longer be an unsolved problem in philosophy.
The Münchhausen trilemma,
also called Agrippa's trilemma, purports that it is impossible to prove any certain truth even in fields such as logic and mathematics. According to this argument, the proof of any theory rests either on circular reasoning, infinite regress, or unproven axioms.
The question hinges on whether color is a product of the mind or an inherent property of objects. While most philosophers will agree that color assignment corresponds to spectra of light frequencies, it is not at all clear whether the particular psychological phenomena of color are imposed on these visual signals by the mind, or whether such qualia are somehow naturally associated with their noumena. Another way to look at this question is to assume two people ("Fred" and "George" for the sake of convenience) see colors differently. That is, when Fred sees the sky, his mind interprets this light signal as blue. He calls the sky "blue." However, when George sees the sky, his mind assigns green to that light frequency. If Fred were able to step into George's mind, he would be amazed that George saw green skies. However, George has learned to associate the word "blue" with what his mind sees as green, and so he calls the sky "blue", because for him the color green has the name "blue." The question is whether blue must be blue for all people, or whether the perception of that particular color is assigned by the mind.
This extends to all areas of the physical reality, where the outside world we perceive is merely a representation of what is impressed upon the senses. The objects we see are in truth wave-emitting (or reflecting) objects which the brain shows to the conscious self in various forms and colors. Whether the colors and forms experienced perfectly match between person to person, may never be known. That people can communicate accurately shows that the order and proportionality in which experience is interpreted is generally reliable. Thus one's reality is, at least, compatible to another person's in terms of structure and ratio.