Senses in the context of "Biological system"

Knowledge is an awareness of facts, a familiarity with individuals and situations, or a practical skill. Knowledge of facts, also called propositional knowledge, is often characterized as true belief that is distinct from opinion or guesswork by virtue of justification. While there is wide agreement among philosophers that propositional knowledge is a form of true belief, many controversies focus on justification. This includes questions like how to understand justification, whether it is needed at all, and whether something else besides it is needed. These controversies intensified in the latter half of the 20th century due to a series of thought experiments called Gettier cases that provoked alternative definitions.

Knowledge can be produced in many ways. The main source of empirical knowledge is perception, which involves the usage of the senses to learn about the external world. Introspection allows people to learn about their internal mental states and processes. Other sources of knowledge include memory, rational intuition, inference, and testimony. According to foundationalism, some of these sources are basic in that they can justify beliefs, without depending on other mental states. Coherentists reject this claim and contend that a sufficient degree of coherence among all the mental states of the believer is necessary for knowledge. According to infinitism, an infinite chain of beliefs is needed.

In semiotics, a sign is anything that communicates a meaning that is not the sign itself to the interpreter of the sign. The meaning can be intentional, as when a word is uttered with a specific meaning, or unintentional, as when a symptom is taken as a sign of a particular medical condition. Signs can communicate through any of the senses, visual, auditory, tactile, olfactory, or taste.

Two major theories describe the way signs acquire the ability to transfer information. Both theories understand the defining property of the sign as a relation between a number of elements. In semiology, the tradition of semiotics developed by Ferdinand de Saussure (1857–1913), the sign relation is dyadic, consisting only of a form of the sign (the signifier) and its meaning (the signified). Saussure saw this relation as being essentially arbitrary (the principle of semiotic arbitrariness), motivated only by social convention. Saussure's theory has been particularly influential in the study of linguistic signs. The other major semiotic theory, developed by Charles Sanders Peirce (1839–1914), defines the sign as a triadic relation as "something that stands for something, to someone in some capacity". This means that a sign is a relation between the sign vehicle (the specific physical form of the sign), a sign object (the aspect of the world that the sign carries meaning about) and an interpretant (the meaning of the sign as understood by an interpreter). According to Peirce, signs can be divided by the type of relation that holds the sign relation together as either icons, indices or symbols. Icons are those signs that signify by means of similarity between sign vehicle and sign object (e.g. a portrait or map), indices are those that signify by means of a direct relation of contiguity or causality between sign vehicle and sign object (e.g. a symptom), and symbols are those that signify through a law or arbitrary social convention.

In the philosophy of mind, innatism is the view that the mind is born with already-formed ideas, knowledge, and beliefs. The opposing doctrine, that the mind is a tabula rasa (blank slate) at birth and all knowledge is gained from experience and the senses, is called empiricism.

Carneades (/kɑːrˈniːədiːz/; Greek: Καρνεάδης, Karneadēs, "of Carnea"; 214/3–129/8 BC) was a Greek philosopher, perhaps the most prominent head of the Skeptical Academy in Ancient Greece. He was born in Cyrene. By the year 159 BC, he had begun to attack many previous dogmatic doctrines, especially Stoicism and even the Epicureans, whom previous skeptics had spared.

As scholarch (leader) of the Academy, he was one of three philosophers sent to Rome in 155 BC where his lectures on the uncertainty of justice caused consternation among leading politicians. He left no writings. His ideas were passed on to us through his successor Clitomachus whose own books were lost but relayed to us indirectly in the writings of Cicero and Sextus Empiricus. He seems to have doubted the ability not just of the senses but of reason too in acquiring truth. His skepticism was, however, moderated by the belief that we can, nevertheless, ascertain probabilities (not in the sense of statistical probability, but in the sense of persuasiveness) of truth, to enable us to act.

Hyperesthesia is a condition that involves an abnormal increase in sensitivity to stimuli of the senses. Stimuli of the senses can include sound that one hears, foods that one tastes, textures that one feels, and so forth. Increased touch sensitivity is referred to as "tactile hyperesthesia", and increased sound sensitivity is called "auditory hyperesthesia". In the context of pain, hyperaesthesia can refer to an increase in sensitivity where there is both allodynia and hyperalgesia.

In psychology, Jeanne Siaud-Facchin uses the term by defining it as an "exacerbation des sens" that characterizes gifted individuals: for them, the sensory information reaches the brain much faster than the average, and the information is processed in a significantly shorter time.