Time perception

From Wikipedia, the free encyclopedia

A contemporary quartz watch

Time perception is a field of study within psychology, cognitive linguistics and neuroscience that refers to the subjective experience, or sense, of time, which is measured by someone's own perception of the duration of the indefinite and unfolding of events. The perceived time interval between two successive events is referred to as perceived duration. Though directly experiencing or understanding another person's perception of time is not possible, such a perception can be objectively studied and inferred through a number of scientific experiments. Time perception is a construction of the sapient brain, but one that is manipulable and distortable under certain circumstances. These temporal illusions help to expose the underlying neural mechanisms of time perception.

Pioneering work, emphasizing species-specific differences, was conducted by Karl Ernst von Baer.

In other words time can be perceived or understood as Subjective Time & Objective Time.

Theories

William J. Friedman (1993) also contrasted two theories for a sense of time:

• The strength model of time memory. This posits a memory trace that persists over time, by which one might judge the age of a memory (and therefore how long ago the event remembered occurred) from the strength of the trace. This conflicts with the fact that memories of recent events may fade more quickly than more distant memories.
• The inference model suggests the time of an event is inferred from information about relations between the event in question and other events whose date or time is known.

Another theory involves the brain's subconscious tallying of "pulses" during a specific interval, forming a biological stopwatch. This theory alleges that the brain can run multiple biological stopwatches at one time depending on the type of task one is involved in. The location of these pulses and what these pulses actually consist of is unclear. This model is only a metaphor and does not stand up in terms of brain physiology or anatomy.

Philosophical perspectives

The specious present is the time duration wherein a state of consciousness is experienced as being in the present. The term was first introduced by the philosopher E. R. Clay in 1882 (E. Robert Kelly), and was further developed by William James. James defined the specious present to be "the prototype of all conceived times... the short duration of which we are immediately and incessantly sensible". In "Scientific Thought" (1930), C. D. Broad further elaborated on the concept of the specious present and considered that the specious present may be considered as the temporal equivalent of a sensory datum. A version of the concept was used by Edmund Husserl in his works and discussed further by Francisco Varela based on the writings of Husserl, Heidegger, and Merleau-Ponty.

Neuroscientific perspectives

Although the perception of time is not associated with a specific sensory system, psychologists and neuroscientists suggest that humans do have a system, or several complementary systems, governing the perception of time. Time perception is handled by a highly distributed system involving the cerebral cortex, cerebellum and basal ganglia. One particular component, the suprachiasmatic nucleus, is responsible for the circadian (or daily) rhythm, while other cell clusters appear to be capable of shorter (ultradian) timekeeping. There is some evidence that very short (millisecond) durations are processed by dedicated neurons in early sensory parts of the brain.

Professor Warren Meck devised a physiological model for measuring the passage of time. He found the representation of time to be generated by the oscillatory activity of cells in the upper cortex. The frequency of these cells' activity is detected by cells in the dorsal striatum at the base of the forebrain. His model separated explicit timing and implicit timing. Explicit timing is used in estimating the duration of a stimulus. Implicit timing is used to gauge the amount of time separating one from an impending event that is expected to occur in the near future. These two estimations of time do not involve the same neuroanatomical areas. For example, implicit timing often occurs to achieve a motor task, involving the cerebellum, left parietal cortex, and left premotor cortex. Explicit timing often involves the supplementary motor area and the right prefrontal cortex.

Two visual stimuli, inside someone's field of view, can be successfully regarded as simultaneous up to five milliseconds.

In the popular essay "Brain Time", David Eagleman explains that different types of sensory information (auditory, tactile, visual, etc.) are processed at different speeds by different neural architectures. The brain must learn how to overcome these speed disparities if it is to create a temporally unified representation of the external world: "if the visual brain wants to get events correct timewise, it may have only one choice: wait for the slowest information to arrive. To accomplish this, it must wait about a tenth of a second. In the early days of television broadcasting, engineers worried about the problem of keeping audio and video signals synchronized. Then they accidentally discovered that they had around a hundred milliseconds of slop: As long as the signals arrived within this window, viewers' brains would automatically resynchronize the signals". He goes on to say that "This brief waiting period allows the visual system to discount the various delays imposed by the early stages; however, it has the disadvantage of pushing perception into the past. There is a distinct survival advantage to operating as close to the present as possible; an animal does not want to live too far in the past. Therefore, the tenth-of- a-second window may be the smallest delay that allows higher areas of the brain to account for the delays created in the first stages of the system while still operating near the border of the present. This window of delay means that awareness is postdictive, incorporating data from a window of time after an event and delivering a retrospective interpretation of what happened."

Experiments have shown that rats can successfully estimate a time interval of approximately 40 seconds, despite having their cortex entirely removed. This suggests that time estimation may be a low level process.

Types of temporal illusions

A temporal illusion is a distortion in the perception of time. Time perception refers to a variety of time-related tasks. For example:

• estimating time intervals, e.g., "When did you last see your primary care physician?";
• estimating time duration, e.g., "How long were you waiting at the doctor's office?"; and
• judging the simultaneity of events (see below for examples).

Short list of types of temporal illusions:

• Telescoping effect: People tend to recall recent events as occurring further back in time than they actually did (backward telescoping) and distant events as occurring more recently than they actually did (forward telescoping)
• Vierordt's law: Shorter intervals tend to be overestimated while longer intervals tend to be underestimated
• Time intervals associated with more changes may be perceived as longer than intervals with fewer changes
• Perceived temporal length of a given task may shorten with greater motivation
• Perceived temporal length of a given task may stretch when broken up or interrupted
• Auditory stimuli may appear to last longer than visual stimuli
• Time durations may appear longer with greater stimulus intensity (e.g., auditory loudness or pitch)
• Simultaneity judgments can be manipulated by repeated exposure to non-simultaneous stimuli.

Kappa effect

The Kappa effect or perceptual time dilation is a form of temporal illusion verifiable by experiment, wherein the temporal duration between a sequence of consecutive stimuli is thought to be relatively longer or shorter than its actual elapsed time, due to the spatial/auditory/tactile separation between each consecutive stimuli. The kappa effect can be displayed when considering a journey made in two parts that take an equal amount of time. Between these two parts, the journey that covers more distance may appear to take longer than the journey covering less distance, even though they take an equal amount of time.

Eye movements and "Chronostasis"

The perception of space and time undergoes distortions during rapid saccadic eye movements.

Chronostasis is a type of temporal illusion in which the first impression following the introduction of a new event or task demand to the brain appears to be extended in time. For example, chronostasis temporarily occurs when fixating on a target stimulus, immediately following a saccade (e.g., quick eye movement). This elicits an overestimation in the temporal duration for which that target stimulus (i.e., postsaccadic stimulus) was perceived. This effect can extend apparent durations by up to 500 ms and is consistent with the idea that the visual system models events prior to perception. The most well-known version of this illusion is known as the stopped-clock illusion, wherein a subject's first impression of the second-hand movement of an analog clock, subsequent to one's directed attention (i.e., saccade) to the clock, is the perception of a slower-than-normal second-hand movement rate (the seconds hand of the clock may seemingly temporarily freeze in place after initially looking at it).

The occurrence of chronostasis extends beyond the visual domain into the auditory and tactile domains. In the auditory domain, chronostasis and duration overestimation occur when observing auditory stimuli. One common example is a frequent occurrence when making telephone calls. If, while listening to the phone's dial tone, research subjects move the phone from one ear to the other, the length of time between rings appears longer. In the tactile domain, chronostasis has persisted in research subjects as they reach for and grasp objects. After grasping a new object, subjects overestimate the time in which their hand has been in contact with this object. In other experiments, subjects turning a light on with a button were conditioned to experience the light before the button press.

Oddball effect

The perception of the duration of an event seems to be modulated by our recent experiences. Humans typically overestimate the perceived duration of the initial event in a stream of identical events and unexpected “oddball” stimuli seem to be perceived as longer in duration, relative to expected or frequently presented “standard” stimuli.

The oddball effect may serve an evolutionarily adapted “alerting” function and is consistent with reports of time slowing down in threatening situations. The effect seems to be strongest for images that are expanding in size on the retina, in other words, that are "looming" or approaching the viewer, and the effect can be eradicated for oddballs that are contracting or perceived to be receding from the viewer. The effect is also reduced or reversed with a static oddball presented amongst a stream of expanding stimuli.

Initial studies suggested that this oddball-induced “subjective time dilation” expanded the perceived duration of oddball stimuli by 30–50% but subsequent research has reported more modest expansion of around 10% or less. The direction of the effect, whether the viewer perceives an increase or a decrease in duration, also seems to be dependent upon the stimulus used.

Effects of emotional states

Awe

Research has suggested the feeling of awe has the ability to expand one's perceptions of time availability. Awe can be characterized as an experience of immense perceptual vastness that coincides with an increase in focus. Consequently, it is conceivable that one's temporal perception would slow down when experiencing awe.

Fear

Possibly related to the oddball effect, research suggests that time seems to slow down for a person during dangerous events (such as a car accident, a robbery, or when a person perceives a potential predator or mate), or when a person skydives or bungee jumps, where they're capable of complex thoughts in what would normally be the blink of an eye (See Fight-or-flight response). This reported slowing in temporal perception may have been evolutionarily advantageous because it may have enhanced one's ability to intelligibly make quick decisions in moments that were of critical importance to our survival. However, even though observers commonly report that time seems to have moved in slow motion during these events, it is unclear whether this is a function of increased time resolution during the event, or instead an illusion created by the remembering of an emotionally salient event.

A strong time dilation effect has been reported for perception of objects that were looming, but not of those retreating, from the viewer, suggesting that the expanding discs — which mimic an approaching object — elicit self-referential processes which act to signal the presence of a possible danger. Anxious people, or those in great fear, experience greater "time dilation" in response to the same threat stimuli due to higher levels of epinephrine, which increases brain activity (an adrenaline rush). In such circumstances, an illusion of time dilation could assist an efficacious escape. When exposed to a threat, three-year-old children were observed to exhibit a similar tendency to overestimate elapsed time.

Research suggests that the effect appears only at the point of retrospective assessment, rather than occurring simultaneously with events as they happened. Perceptual abilities were tested during a frightening experience — a free fall — by measuring people's sensitivity to flickering stimuli. The results showed that the subjects' temporal resolution was not improved as the frightening event was occurring. Events appear to have taken longer only in retrospect, possibly because memories were being more densely packed during the frightening situation.

People shown extracts from films known to induce fear often overestimated the elapsed time of a subsequently presented visual stimulus, whereas people shown emotionally neutral clips (weather forecasts and stock market updates) or those known to evoke feelings of sadness showed no difference. It is argued that fear prompts a state of arousal in the amygdala, which increases the rate of a hypothesized "internal clock". This could be the result of an evolved defensive mechanism triggered by a threatening situation.

Empathy

The perception of another persons' emotions can also change our sense of time. The theory of embodied mind (or cognition), caused by mirror neurons, helps explain how the perception of other people's emotions has the ability to change one's own sense of time. Embodied cognition hinges on an internal process that mimics or simulates another's emotional state. For example, if person #1 spends time with person #2 who speaks and walks incredibly slowly, person #1's internal clock may slow down.

Depression

Depression may increase one's ability to perceive time accurately. One study assessed this concept by asking subjects to estimate the amount of time that passed during intervals ranging from 3 seconds to 65 seconds. Results indicated that depressed subjects more accurately estimated the amount of time that had passed than non-depressed patients; non-depressed subjects overestimated the passing of time. This difference was hypothesized to be because depressed subjects focused less on external factors that may skew their judgment of time. The authors termed this hypothesized phenomenon "depressive realism."

Changes with age

Psychologists have found that the subjective perception of the passing of time tends to speed up with increasing age in humans. This often causes people to increasingly underestimate a given interval of time as they age. This fact can likely be attributed to a variety of age-related changes in the aging brain, such as the lowering in dopaminergic levels with older age; however, the details are still being debated.^[58][59][60] In an experimental study involving a group of subjects aged between 19 and 24 and a group between 60 and 80, the participants' abilities to estimate 3 minutes of time were compared. The study found that an average of 3 minutes and 3 seconds passed when participants in the younger group estimated that 3 minutes had passed, whereas the older group's estimate for when 3 minutes had passed came after an average of 3 minutes and 40 seconds.

Very young children literally "live in time" before gaining an awareness of its passing. A child will first experience the passing of time when he or she can subjectively perceive and reflect on the unfolding of a collection of events. A child's awareness of time develops during childhood when the child's attention and short-term memory capacities form — this developmental process is thought to be dependent on the slow maturation of the prefrontal cortex and hippocampus.

One day to an 11-year-old would be approximately 1/4,000 of their life, while one day to a 55-year-old would be approximately 1/20,000 of their life. This helps to explain why a random, ordinary day may therefore appear longer for a young child than an adult. The short term appears to go faster in proportion to the square root of the perceiver's age. So a year would be experienced by a 55-year-old as passing approximately 2¼ times more quickly than a year experienced by an 11-year-old. If long-term time perception is based solely on the proportionality of a person's age, then the following four periods in life would appear to be quantitatively equal: ages 5–10 (1x), ages 10–20 (2x), ages 20–40 (4x), age 40–80 (8x).

The common explanation is that most external and internal experiences are new for young children but repetitive for adults. Children have to be extremely engaged (i.e. dedicate many neural resources or significant brain power) in the present moment because they must constantly reconfigure their mental models of the world to assimilate it and manage behaviour properly. Adults however may rarely need to step outside mental habits and external routines. When an adult frequently experiences the same stimuli, they seem "invisible" because already sufficiently and effectively mapped by the brain. This phenomenon is known as neural adaptation. Thus, the brain will record fewer densely rich memories during these frequent periods of disengagement from the present moment. Consequently, the subjective perception is often that time passes by at a faster rate with age.

Effects of drugs

Stimulants produce overestimates of time duration, whereas depressants and anaesthetics produce underestimates of time duration.

Psychoactive drugs can alter the judgment of time. These include traditional psychedelics such as LSD, psilocybin, and mescaline as well as the dissociative class of psychedelics such as PCP, ketamine and dextromethorphan. At higher doses time may appear to slow down, speed up or seem out of sequence. In a 2007 study, psilocybin was found to significantly impair the ability to reproduce interval durations longer than 2.5 seconds, significantly impair synchronizing motor actions (taps on a computer keyboard) with regularly occurring tones, and impair the ability to keep tempo when asked to tap on a key at a self-paced but consistent interval. In 1955, British MP Christopher Mayhew took mescaline hydrochloride in an experiment under the guidance of his friend, Dr Humphry Osmond. On the BBC documentary The Beyond Within, he described that half a dozen times during the experiment, he had "a period of time that didn't end for [him]".

Stimulants can lead both humans and rats to overestimate time intervals, while depressants can have the opposite effect. The level of activity in the brain of neurotransmitters such as dopamine and norepinephrine may be the reason for this. Dopamine has a particularly strong connection with one's perception of time. Drugs that activate dopamine receptors speed up one's perception of time, while dopamine antagonists cause one to feel that time is passing slowly.

The effect of cannabis on time perception has been studied with inconclusive results.

Effects of body temperature

Time perception may speed up as body temperature rises, and slow down as body temperature lowers. This is especially true during stressful events.

Reversal of temporal order judgment

Numerous experimental findings suggest that temporal order judgments of actions preceding effects can be reversed under special circumstances. Experiments have shown that sensory simultaneity judgments can be manipulated by repeated exposure to non-simultaneous stimuli. In an experiment conducted by David Eagleman, a temporal order judgment reversal was induced in subjects by exposing them to delayed motor consequences. In the experiment, subjects played various forms of video games. Unknown to the subjects, the experimenters introduced a fixed delay between the mouse movements and the subsequent sensory feedback. For example, a subject may not see a movement register on the screen until 150 milliseconds after the mouse had moved. Participants playing the game quickly adapted to the delay and felt as though there was less delay between their mouse movement and the sensory feedback. Shortly after the experimenters removed the delay, the subjects commonly felt as though the effect on the screen happened just before they commanded it. This work addresses how the perceived timing of effects is modulated by expectations, and the extent to which such predictions are quickly modifiable. In an experiment conducted by Haggard and colleagues in 2002, participants pressed a button that triggered a flash of light at a distance after a slight delay of 100 milliseconds. By repeatedly engaging in this act, participants had adapted to the delay (i.e., they experienced a gradual shortening in the perceived time interval between pressing the button and seeing the flash of light). The experimenters then showed the flash of light instantly after the button was pressed. In response, subjects often thought that the flash (the effect) had occurred before the button was pressed (the cause). Additionally, when the experimenters slightly reduced the delay, and shortened the spatial distance between the button and the flash of light, participants had often claimed again to have experienced the effect before the cause.

Several experiments also suggest that temporal order judgment of a pair of tactile stimuli delivered in rapid succession, one to each hand, is noticeably impaired (i.e., misreported) by crossing the hands over the midline. However, congenitally blind subjects showed no trace of temporal order judgment reversal after crossing the arms. These results suggest that tactile signals taken in by the congenitally blind are ordered in time without being referred to a visuospatial representation. Unlike the congenitally blind subjects, the temporal order judgments of the late-onset blind subjects were impaired when crossing the arms to a similar extent as non-blind subjects. These results suggest that the associations between tactile signals and visuospatial representation is maintained once it is accomplished during infancy. Some research studies have also found that the subjects showed reduced deficit in tactile temporal order judgments when the arms were crossed behind their back than when they were crossed in front.

Flash-lag effect

In an experiment, participants were told to stare at an "x" symbol on a computer screen whereby a moving blue doughnut-like ring repeatedly circled the fixed "x" point. Occasionally, the ring would display a white flash for a split second that physically overlapped the ring's interior. However, when asked what was perceived, participants responded that they saw the white flash lagging behind the center of the moving ring. In other words, despite the reality that the two retinal images were actually spatially aligned, the flashed object was usually observed to trail a continuously moving object in space — a phenomenon referred to as the flash-lag effect.

The first proposed explanation, called the 'motion extrapolation' hypothesis, is that the visual system extrapolates the position of moving objects but not flashing objects when accounting for neural delays (i.e., the lag time between the retinal image and the observer's perception of the flashing object). The second proposed explanation by David Eagleman and Sejnowski, called the 'latency difference' hypothesis, is that the visual system processes moving objects at a faster rate than flashed objects. In the attempt to disprove the first hypothesis, David Eagleman conducted an experiment in which the moving ring suddenly reverses direction to spin in the other way as the flashed object briefly appears. If the first hypothesis were correct, we would expect that, immediately following reversal, the moving object would be observed as lagging behind the flashed object. However, the experiment revealed the opposite — immediately following reversal, the flashed object was observed as lagging behind the moving object. This experimental result supports of the 'latency difference' hypothesis. A recent study tries to reconcile these different approaches by approaching perception as an inference mechanism aiming at describing what is happening at the present time.

Effects of clinical disorders

Parkinson's disease, schizophrenia, and attention deficit hyperactivity disorder (ADHD) have been linked to abnormalities in dopamine levels in the brain as well as to noticeable impairments in time perception. Neuropharmacological research indicates that the internal clock, used to time durations in the seconds-to-minutes range, is linked to dopamine function in the basal ganglia. Studies in which children with ADHD are given time estimation tasks shows that time passes very slowly for them. Children with Tourette’s Syndrome, in contrast, who need to use the pre-frontal cortex to help them control their tics, are better at estimating intervals of time just over a second than other children.

In his book Awakenings, the neurologist Dr. Oliver Sacks discussed how patients with Parkinson's disease experience deficits in their awareness of time and tempo. For example, Mr E, when asked to clap his hands steadily and regularly, did so for the first few claps before clapping faster and irregularly, culminating in an apparent freezing of motion. When he finished, Mr E asked if his observers were glad he did it correctly, to which they replied "no". Mr E was offended by this because to him, his claps were regular and steady.

Dopamine is also theorized to play a role in the attention deficits present with attention deficit hyperactivity disorder. Specifically, dopaminergic systems are involved in working memory and inhibitory processes, both of which are believed central to ADHD pathology. Children with ADHD have also been found to be significantly impaired on time discrimination tasks (telling the difference between two stimuli of different temporal lengths) and respond earlier on time reproduction tasks (duplicating the duration of a presented stimulus) than controls.

Along with other perceptual abnormalities, it has been noted by psychologists that schizophrenia patients have an altered sense of time. This was first described in psychology by Minkowski in 1927. Many schizophrenic patients stop perceiving time as a flow of causally linked events. It has been suggested that there is usually a delay in time perception in schizophrenic patients compared to normal subjects.

These defects in time perception may play a part in the hallucinations and delusions experienced by schizophrenic patients according to some studies. Some researchers suggest that "abnormal timing judgment leads to a deficit in action attribution and action perception."

Sleep

The perception of time is temporarily suspended during sleep, or more often during REM sleep. This can be attributed to the altered state of consciousness associated with sleep that prevents awareness of the surroundings, which would make it difficult to remain informed of the passing of time — new memories are rarely made during sleep. Therefore, upon waking up in the morning a person subjectively feels no time has passed but reasons that many hours have elapsed simply because it is now light outside. The passing of time must be inferred by observations of objects (e.g., the sun’s location, the moon, a clock's time) relative to the previous evening. So, time may feel as passing "faster" during sleep due to the lack of reference points. Another experience sometimes reported is a long dream seeming to go on for hours when it actually lasted only a few seconds or minutes.

Substance theory

From Wikipedia, the free encyclopedia

Substance theory, or substance–attribute theory, is an ontological theory about objecthood, positing that a substance is distinct from its properties. A thing-in-itself is a property-bearer that must be distinguished from the properties it bears.

Substance is a key concept in ontology and metaphysics, which may be classified into monist, dualist, or pluralist varieties according to how many substances or individuals are said to populate, furnish, or exist in the world. According to monistic views, there is only one substance. Stoicism and Spinoza, for example, hold monistic views, that pneuma or God, respectively, is the one substance in the world. These modes of thinking are sometimes associated with the idea of immanence. Dualism sees the world as being composed of two fundamental substances, for example, the Cartesian substance dualism of mind and matter. Pluralist philosophies include Plato's Theory of Forms and Aristotle's hylomorphic categories.

Ancient Greek philosophy

Aristotle

Aristotle used the term "substance" (Greek: οὐσία ousia) in a secondary sense for genera and species understood as hylomorphic forms. Primarily, however, he used it with regard to his category of substance, the specimen ("this person" or "this horse") or individual, qua individual, who survives accidental change and in whom the essential properties inhere that define those universals.

A substance—that which is called a substance most strictly, primarily, and most of all—is that which is neither said of a subject nor in a subject, e.g. the individual man or the individual horse. The species in which the things primarily called substances are, are called secondary substances, as also are the genera of these species. For example, the individual man belongs in a species, man, and animal is a genus of the species; so these—both man and animal—are called secondary substances.

— Aristotle, Categories 2a13 (trans. J. L. Ackrill)

In chapter 6 of book I the Physics Aristotle argues that any change must be analysed in reference to the property of an invariant subject: as it was before the change and thereafter. Thus, in his hylomorphic account of change, matter serves as a relative substratum of transformation, i.e., of changing (substantial) form. In the Categories, properties are predicated only of substance, but in chapter 7 of book I of the Physics, Aristotle discusses substances coming to be and passing away in the "unqualified sense" wherein primary substances (πρῶται οὐσίαι; Categories 2a35) are generated from (or perish into) a material substratum by having gained (or lost) the essential property that formally defines substances of that kind (in the secondary sense). Examples of such a substantial change include not only conception and dying, but also metabolism, e.g., the bread a man eats becomes the man. On the other hand, in accidental change, because the essential property remains unchanged, by identifying the substance with its formal essence, substance may thereby serve as the relative subject matter or property-bearer of change in a qualified sense (i.e., barring matters of life or death). An example of this sort of accidental change is a change of color or size: a tomato becomes red, or a juvenile horse grows.

Aristotle thinks that in addition to primary substances (which are particulars), there are secondary substances (δεύτεραι οὐσίαι), which are universals (Categories 2a11–a18).

Neither the "bare particulars" nor "property bundles" of modern theory have their antecedent in Aristotle, according to whom, all matter exists in some form. There is no prime matter or pure elements, there is always a mixture: a ratio weighing the four potential combinations of primary and secondary properties and analysed into discrete one-step and two-step abstract transmutations between the elements.

However, according to Aristotle's theology, a form of invariant form exists without matter, beyond the cosmos, powerless and oblivious, in the eternal substance of the unmoved movers.

Stoicism

The Stoics rejected the idea that incorporeal beings inhere in matter, as taught by Plato. They believed that all being is corporeal infused with a creative fire called pneuma. Thus they developed a scheme of categories different from Aristotle's based on the ideas of Anaxagoras and Timaeus.

Neoplatonism

Neoplatonists argue that beneath the surface phenomena that present themselves to our senses are three higher spiritual principles or hypostases, each one more sublime than the preceding. For Plotinus, these are the soul or world-soul, being/intellect or divine mind (nous), and "the one".

Early modern philosophy

means by a substance an entity which exists in such a way that it needs no other entity in order to exist. Therefore, only God is a substance in this strict sense. However, he extends the term to created things, which need only the concurrence of God to exist. He maintained that two of these are mind and body, each being distinct from the other in their attributes and therefore in their essence, and neither needing the other in order to exist. This is Descartes' substance dualism.

Baruch Spinoza denied Descartes' "real distinction" between mind and matter. Substance, according to Spinoza, is one and indivisible, but has multiple "attributes". He regards an attribute, though, as "what we conceive as constituting the [single] essence of substance". The single essence of one substance can be conceived of as material and also, consistently, as mental. What is ordinarily called the natural world, together with all the individuals in it, is immanent in God: hence his famous phrase deus sive natura ("God or Nature").

John Locke views substance through a corpuscularian lens where it exhibits two types of qualities which both stem from a source. He believes that humans are born tabula rasa or “blank slate” – without innate knowledge. In An Essay Concerning Human Understanding Locke writes that “first essence may be taken for the very being of anything, whereby it is, what it is.” If humans are born without any knowledge, the way to receive knowledge is through perception of a certain object. But, according to Locke, an object exists in its primary qualities, no matter whether the human perceives it or not; it just exists. For example, an apple has qualities or properties that determine its existence apart from human perception of it, such as its mass or texture. The apple itself is also “pure substance in which is supposed to provide some sort of ‘unknown support’ to the observable qualities of things”^[vague] that the human mind perceives. The foundational or support qualities are called primary essences which “in the case of physical substances, are the underlying physical causes of the object's observable qualities”. But then what is an object except “the owner or support of other properties”? Locke rejects Aristotle’s category of the forms, and develops mixed ideas about what substance or “first essence” means. Locke’s solution to confusion about first essence is to argue that objects simply are what they are – made up of microscopic particles existing because they exist. According to Locke, the mind cannot completely grasp the idea of a substance as it “always falls beyond knowledge”. There is a gap between what first essence truly means and the mind’s perception of it that Locke believes the mind cannot bridge, objects in their primary qualities must exist apart from human perception.

The molecular combination of atoms in first essence then forms the solid base that humans can perceive and add qualities to describe - the only way humans can possibly begin to perceive an object. The way to perceive the qualities of an apple is from the combination of the primary qualities to form the secondary qualities. These qualities are then used to group the substances into different categories that “depend on the properties [humans] happen to be able to perceive”. The taste of an apple or the feeling of its smoothness are not traits inherent to the fruit but are the power of the primary qualities to produce an idea about that object in the mind. The reason that humans can’t sense the actual primary qualities is the mental distance from the object; thus, Locke argues, objects remain nominal for humans. Therefore, the argument then returns to how “a philosopher has no other idea of those substances than what is framed by a collection of those simple ideas which are found in them.” The mind’s conception of substances “[is] complex rather than simple” and “has no (supposedly innate) clear and distinct idea of matter that can be revealed through intellectual abstraction away from sensory qualities”.

The last quality of substance is the way the perceived qualities seem to begin to change – such as a candle melting; this quality is called the tertiary quality. Tertiary qualities “of a body are those powers in it that, by virtue of its primary qualities, give it the power to produce observable changes in the primary qualities of other bodies”; “the power of the sun to melt wax is a tertiary quality of the sun”. They are “mere powers; qualities such as flexibility, ductility; and the power of sun to melt wax”. This goes along with “passive power: the capacity a thing has for being changed by another thing”. In any object, at the core are the primary qualities (unknowable by the human mind), the secondary quality (how primary qualities are perceived), and tertiary qualities (the power of the combined qualities to make a change to itself and other objects). The corpuscularian hypothesis, by Robert Boyle, states that "all material bodies are composites of ultimately small particles of matter" that "have the same material qualities as the larger composite bodies do". Using this basis, Locke defines his first group, primary qualities, as "the ones that a body doesn't lose, however much it alters". The materials retain their primary qualities even if they are broken down because of the unchanging nature of their atomic particles. If someone is curious about an object and they say it is solid and extended, these two descriptors are primary qualities. The second group consists of secondary qualities which are "really nothing but the powers to produce various sensations in us by their primary qualities". Locke argues that the impressions our senses perceive from the objects (i.e. taste, sounds, colors, etc.) are not natural properties of the object itself, but things they induce in us by means of the "size, shape, texture, and motion of their imperceptible parts", or their atoms. The bodies send insensible particles to our senses which let us perceive the object through different faculties; what we perceive is based on the object's composition. With these qualities, people can achieve the object through bringing "co-existing powers and sensible qualities to a common ground for explanation". Locke supposes that one wants to know what "binds these qualities" into an object, and argues that a "substratum" or "substance" has this effect, defining "substance" as follows:

The idea that we have, to which we give the general name substance, being nothing but the supposed, but unknown, support of those qualities we find existing, which we imagine cannot subsist sine re substante, without something to support them, we call that support substantia; which, according to the true import of the word, is, in plain English, standing under or upholding.

— John Locke, An Essay Concerning Human Understanding; book 2, chapter 23; "Of our Complex Ideas of Substances"

This substratum is a construct of the mind in an attempt to bind all the qualities seen together; it is only "a supposition of an unknown support of qualities that are able to cause simple ideas in us". Without making a substratum, people would be at a loss as to how different qualities relate. Locke does, however, mention that this substratum is an unknown, relating it to the story of the world on the turtle's back and how the believers eventually had to concede that the turtle just rested on "something he knew not what". This is how the mind perceives all things and from which it can make ideas about them; it is entirely relative, but it does provide a "regularity and consistency to our ideas". Substance, overall, has two sets of qualities that define it, and how we perceive it. These qualities rush to our minds which must organize them. As a result, it creates a substratum for each object to which it groups related qualities.

Irreducible concepts

Two irreducible concepts encountered in substance theory are the bare particular and inherence.

Bare particular

In substance theory, a bare particular of an object is the element without which the object would not exist, that is, its substance, which exists independently from its properties, even if it is impossible for it to lack properties entirely. It is "bare" because it is considered without its properties and "particular" because it is not abstract. The properties that the substance has are said to inhere in the substance.

Inherence

Another primitive concept in substance theory is the inherence of properties within a substance. For example, in the sentence, "The apple is red" substance theory says that red inheres in the apple. Substance theory takes the meaning of an apple having the property of redness to be understood, and likewise that of a property's inherence in substance, which is similar to, but not identical with, being part of the substance.

The inverse relation is participation. Thus in the example above, just as red inheres in the apple, so the apple participates in red.

Arguments supporting the theory

Two common arguments supporting substance theory are the argument from grammar and the argument from conception.

Argument from grammar

The argument from grammar uses traditional grammar to support substance theory. For example, the sentence "Snow is white" contains a grammatical subject "snow" and the predicate "is white", thereby asserting snow is white. The argument holds that it makes no grammatical sense to speak of "whiteness" disembodied, without asserting that snow or something else is white. Meaningful assertions are formed by virtue of a grammatical subject, of which properties may be predicated, and in substance theory, such assertions are made with regard to a substance.

Bundle theory rejects the argument from grammar on the basis that a grammatical subject does not necessarily refer to a metaphysical subject. Bundle theory, for example, maintains that the grammatical subject of statement refers to its properties. For example, a bundle theorist understands the grammatical subject of the sentence, "Snow is white", to be a bundle of properties such as white. Accordingly, one can make meaningful statements about bodies without referring to substances.

Argument from conception

Another argument for the substance theory is the argument from conception. The argument claims that in order to conceive of an object's properties, like the redness of an apple, one must conceive of the object that has those properties. According to the argument, one cannot conceive of redness, or any other property, distinct from the substance that has that property.

Criticism

The idea of substance was famously critiqued by David Hume, who held that since substance cannot be perceived, it should not be assumed to exist. But the claim that substance cannot be perceived is neither clear nor obvious, and neither is the implication obvious.

Friedrich Nietzsche, and after him Martin Heidegger, Michel Foucault and Gilles Deleuze also rejected the notion of "substance", and in the same movement the concept of subject - seeing both concepts as holdovers from Platonic idealism. For this reason, Althusser's "anti-humanism" and Foucault's statements were criticized, by Jürgen Habermas and others, for misunderstanding that this led to a fatalist conception of social determinism. For Habermas, only a subjective form of liberty could be conceived, to the contrary of Deleuze who talks about "a life", as an impersonal and immanent form of liberty.

For Heidegger, Descartes means by "substance" that by which "we can understand nothing else than an entity which is in such a way that it need no other entity in order to be." Therefore, only God is a substance as Ens perfectissimus (most perfect being). Heidegger showed the inextricable relationship between the concept of substance and of subject, which explains why, instead of talking about "man" or "humankind", he speaks about the Dasein, which is not a simple subject, nor a substance.

Alfred North Whitehead has argued that the concept of substance has only a limited applicability in everyday life and that metaphysics should rely upon the concept of process.

Roman Catholic theologian Karl Rahner, as part of his critique of transubstantiation, rejected substance theory and instead proposed the doctrine of transfinalization, which he felt was more attuned to modern philosophy. However, this doctrine was rejected by Pope Paul VI in his encyclical Mysterium fidei.

Bundle theory

In direct opposition to substance theory is bundle theory, whose most basic premise is that all concrete particulars are merely constructions or 'bundles' of attributes or qualitative properties:

Necessarily, for any concrete entity, ${\displaystyle a}$, if for any entity, ${\displaystyle b}$, ${\displaystyle b}$ is a constituent of ${\displaystyle a}$, then ${\displaystyle b}$ is an attribute.

The bundle theorist's principal objections to substance theory concern the bare particulars of a substance, which substance theory considers independently of the substance's properties. The bundle theorist objects to the notion of a thing with no properties, claiming that such a thing is inconceivable and citing John Locke, who described a substance as "a something, I know not what." To the bundle theorist, as soon as one has any notion of a substance in mind, a property accompanies that notion.

Identity of indiscernibles counterargument

The indiscernibility argument from the substance theorist targets those bundle theorists who are also metaphysical realists. Metaphysical realism uses the identity of universals to compare and identify particulars. Substance theorists say that bundle theory is incompatible with metaphysical realism due to the identity of indiscernibles: particulars may differ from one another only with respect to their attributes or relations.

The substance theorist's indiscernibility argument against the metaphysically realistic bundle theorist states that numerically different concrete particulars are discernible from the self-same concrete particular only by virtue of qualitatively different attributes.

Necessarily, for any complex objects, ${\displaystyle a}$ and ${\displaystyle b}$, if for any entity, ${\displaystyle c}$, ${\displaystyle c}$ is a constituent of ${\displaystyle a}$ if and only if ${\displaystyle c}$ is a constituent of ${\displaystyle b}$, then ${\displaystyle a}$ is numerically identical with ${\displaystyle b}$.

The indiscernibility argument points out that if bundle theory and discernible concrete particulars theory explain the relationship between attributes, then the identity of indiscernibles theory must also be true:

Necessarily, for any concrete objects, ${\displaystyle a}$ and ${\displaystyle b}$, if for any attribute, Φ, Φ is an attribute of ${\displaystyle a}$ if and only if Φ is an attribute of ${\displaystyle b}$, then ${\displaystyle a}$ is numerically identical with ${\displaystyle b}$.

The indiscernibles argument then asserts that the identity of indiscernibles is violated, for example, by identical sheets of paper. All of their qualitative properties are the same (e.g. white, rectangular, 9 x 11 inches...) and thus, the argument claims, bundle theory and metaphysical realism cannot both be correct.

However, bundle theory combined with trope theory (as opposed to metaphysical realism) avoids the indiscernibles argument because each attribute is a trope if can only be held by only one concrete particular.

The argument does not consider whether "position" should be considered an attribute or relation. It is after all through the differing positions that we in practice differentiate between otherwise identical pieces of paper.

Being

From Wikipedia, the free encyclopedia

In philosophy, being refers to the existence of a thing. Anything that exists has being. Ontology is the branch of philosophy that studies being. Being is a concept encompassing objective and subjective features of reality and existence. Anything that partakes in being is also called a "being", though often this usage is limited to entities that have subjectivity (as in the expression "human being"). The notion of "being" has, inevitably, been elusive and controversial in the history of philosophy, beginning in Western philosophy with attempts among the pre-Socratics to deploy it intelligibly. The first effort to recognize and define the concept came from Parmenides, who famously said of it that "what is-is". Common words such as "is", "are", and "am" refer directly or indirectly to being.

As an example of efforts in recent times, Martin Heidegger (who himself drew on ancient Greek sources) adopted after German terms like Dasein to articulate the topic. Several modern approaches build on such continental European exemplars as Heidegger, and apply metaphysical results to the understanding of human psychology and the human condition generally (notably in the Existentialist tradition). By contrast, in mainstream Analytical philosophy the topic is more confined to abstract investigation, in the work of such influential theorists as W. V. O. Quine, to name one of many. One of the most fundamental questions that continues to exercise philosophers is posed by William James: "How comes the world to be here at all instead of the nonentity which might be imagined in its place? ... from nothing to being there is no logical bridge."

The substantial being

Being and the substance theorists

The deficit of such a bridge was first encountered in history by the Pre-Socratic philosophers during the process of evolving a classification of all beings (noun). Aristotle, who wrote after the Pre-Socratics, applies the term category (perhaps not originally) to ten highest-level classes. They comprise one category of substance (ousiae) existing independently (man, tree) and nine categories of accidents, which can only exist in something else (time, place). In Aristotle, substances are to be clarified by stating their definition: a note expressing a larger class (the genus) followed by further notes expressing specific differences (differentiae) within the class. The substance so defined was a species. For example, the species, man, may be defined as an animal (genus) that is rational (difference). As the difference is potential within the genus; that is, an animal may or may not be rational, the difference is not identical to, and may be distinct from, the genus.

Applied to being, the system fails to arrive at a definition for the simple reason that no difference can be found. The species, the genus, and the difference are all equally being: a being is a being that is being. The genus cannot be nothing because nothing is not a class of everything. The trivial solution that being is being added to nothing is only a tautology: being is being. There is no simpler intermediary between being and non-being that explains and classifies being.

The Being according to Parmenides is like the mass of a sphere.

Pre-Socratic reaction to this deficit was varied. As substance theorists they accepted a priori the hypothesis that appearances are deceiving, that reality is to be reached through reasoning. Parmenides reasoned that if everything is identical to being and being is a category of the same thing then there can be neither differences between things nor any change. To be different, or to change, would amount to becoming or being non-being; that is, not existing. Therefore, being is a homogeneous and non-differentiated sphere and the appearance of beings is illusory. Heraclitus, on the other hand, foreshadowed modern thought by denying existence. Reality does not exist, it flows, and beings are an illusion upon the flow.

Aristotle knew of this tradition when he began his Metaphysics, and had already drawn his own conclusion, which he presented under the guise of asking what being is:

"And indeed the question which was raised of old is raised now and always, and is always the subject of doubt, viz., what being is, is just the question, what is substance? For it is this that some assert to be one, others more than one, and that some assert to be limited in number, others unlimited. And so we also must consider chiefly and primarily and almost exclusively what that is which is in this sense."

and reiterates in no uncertain terms: "Nothing, then, which is not a species of a genus will have an essence – only species will have it ....". Being, however, for Aristotle, is not a genus.

Aristotle's theory of act and potency

One might expect a solution to follow from such certain language but none does. Instead Aristotle launches into a rephrasing of the problem, the Theory of Act and Potency. In the definition of man as a two-legged animal Aristotle presumes that "two-legged" and "animal" are parts of other beings, but as far as man is concerned, are only potentially man. At the point where they are united into a single being, man, the being, becomes actual, or real. Unity is the basis of actuality: "... 'being' is being combined and one, and 'not being' is being not combined but more than one." Actuality has taken the place of existence, but Aristotle is no longer seeking to know what the actual is; he accepts it without question as something generated from the potential. He has found a "half-being" or a "pre-being", the potency, which is fully being as part of some other substance. Substances, in Aristotle, unite what they actually are now with everything they might become.

The transcendental being

Some of Thomas Aquinas' propositions were reputedly condemned by Étienne Tempier, the local Bishop of Paris (not the Papal Magisterium itself) in 1270 and 1277, but his dedication to the use of philosophy to elucidate theology was so thorough that he was proclaimed a Doctor of the Church in 1568. Those who adopt it are called Thomists.

Thomistic analogical predication of being

In a single sentence, parallel to Aristotle's statement asserting that being is substance, St. Thomas pushes away from the Aristotelian doctrine: "Being is not a genus, since it is not predicated univocally but only analogically." His term for analogy is Latin analogia. In the categorical classification of all beings, all substances are partly the same: man and chimpanzee are both animals and the animal part in man is "the same" as the animal part in chimpanzee. Most fundamentally all substances are matter, a theme taken up by science, which postulated one or more matters, such as earth, air, fire or water (Empedocles). In today's chemistry the carbon, hydrogen, oxygen and nitrogen in a chimpanzee are identical to the same elements in a man.

The original text reads, "Although equivocal predications must be reduced to univocal, still in actions, the non-univocal agent must precede the univocal agent. For the non-univocal agent is the universal cause of the whole species, as for instance the sun is the cause of the generation of all men; whereas the univocal agent is not the universal efficient cause of the whole species (otherwise it would be the cause of itself, since it is contained in the species), but is a particular cause of this individual which it places under the species by way of participation. Therefore the universal cause of the whole species is not an univocal agent; and the universal cause comes before the particular cause. But this universal agent, whilst it is not univocal, nevertheless is not altogether equivocal, otherwise it could not produce its own likeness, but rather it is to be called an analogical agent, as all univocal predications are reduced to one first non-univocal analogical predication, which is being."

If substance is the highest category and there is no substance, being, then the unity perceived in all beings by virtue of their existing must be viewed in another way. St. Thomas chose the analogy: all beings are like, or analogous to, each other in existing. This comparison is the basis of his Analogy of Being. The analogy is said of being in many different ways, but the key to it is the real distinction between existence and essence. Existence is the principle that gives reality to an essence not the same in any way as the existence: "If things having essences are real, and it is not of their essence to be, then the reality of these things must be found in some principle other than (really distinct from) their essence." Substance can be real or not. What makes an individual substance – a man, a tree, a planet – real is a distinct act, a "to be", which actuates its unity. An analogy of proportion is therefore possible: "essence is related to existence as potency is related to act."

Existences are not things; they do not themselves exist, they lend themselves to essences, which do not intrinsically have them. They have no nature; an existence receives its nature from the essence it actuates. Existence is not being; it gives being – here a customary phrase is used, existence is a principle (a source) of being, not a previous source, but one which is continually in effect. The stage is set for the concept of God as the cause of all existence, who, as the Almighty, holds everything actual without reason or explanation as an act purely of will.

The transcendentals

Aristotle's classificatory scheme had included the five predicables, or characteristics that might be predicated of a substance. One of these was the property, an essential universal true of the species, but not in the definition (in modern terms, some examples would be grammatical language, a property of man, or a spectral pattern characteristic of an element, both of which are defined in other ways). Pointing out that predicables are predicated univocally of substances; that is, they refer to "the same thing" found in each instance, St. Thomas argued that whatever can be said about being is not univocal, because all beings are unique, each actuated by a unique existence. It is the analogous possession of an existence that allows them to be identified as being; therefore, being is an analogous predication.

Whatever can be predicated of all things is universal-like but not universal, category-like but not a category. St. Thomas called them (perhaps not originally) the transcendentia, "transcendentals", because they "climb above" the categories, just as being climbs above substance. Later academics also referred to them as "the properties of being." The number is generally three or four.

Being in Islamic philosophy

The nature of "being" has also been debated and explored in Islamic philosophy, notably by Ibn Sina (Avicenna), Suhrawardi, and Mulla Sadra.

A modern linguistic approach which notices that Persian language has exceptionally developed two kinds of "is"es, i.e. ast ("is", as a copula) and hast (as an existential "is") examines the linguistic properties of the two lexemes in the first place, then evaluates how the statements made by other languages with regard to being can stand the test of Persian frame of reference.

In this modern linguistic approach, it is noticed that the original language of the source, e.g. Greek (like German or French or English), has only one word for two concepts, ast and hast, or, like Arabic, has no word at all for either word. It therefore exploits the Persian hast (existential is) versus ast (predicative is or copula) to address both Western and Islamic ontological arguments on being and existence.

This linguistic method shows the scope of confusion created by languages which cannot differentiate between existential be and copula. It manifests, for instance, that the main theme of Heidegger's Being and Time is astī (is-ness) rather than hastī (existence). When, in the beginning of his book, Heidegger claims that people always talk about existence in their everyday language, without knowing what it means, the example he resorts to is: "the sky is blue" which in Persian can be ONLY translated with the use of the copula ast, and says nothing about being or existence.

In the same manner, the linguistic method addresses the ontological works written in Arabic. Since Arabic, like Latin in Europe, had become the official language of philosophical and scientific works in the so-called Islamic World, the early Persian or Arab philosophers had difficulty discussing being or existence, since the Arabic language, like other Semitic languages, had no verb for either predicative "be" (copula) or existential "be". So if you try to translate the aforementioned Heidegger's example into Arabic it appears as السماء زرقاء (viz. "The Sky-- blue") with no linking "is" to be a sign of existential statement. To overcome the problem, when translating the ancient Greek philosophy, certain words were coined like ایس aysa (from Arabic لیس laysa 'not') for 'is'. Eventually the Arabic verb وجد wajada (to find) prevailed, since it was thought that whatever is existent, is to be "found" in the world. Hence existence or Being was called وجود wujud (Cf. Swedish finns [found]> there exist; also the Medieval Latin coinage of exsistere 'standing out (there in the world)' > appear> exist).

Now, with regard to the fact that Persian, as the mother tongue of both Avicenna and Sadrā, was in conflict with either Greek or Arabic in this regard, these philosophers should have been warned implicitly by their mother tongue not to confuse two kinds of linguistic beings (viz. copula vs. existential). In fact when analyzed thoroughly, copula, or Persian ast ('is') indicates an ever-moving chain of relations with no fixed entity to hold onto (every entity, say A, will be dissolved into "A is B" and so on, as soon as one tries to define it). Therefore, the whole reality or what we see as existence ("found" in our world) resembles an ever-changing world of astī (is-ness) flowing in time and space. On the other hand, while Persian ast can be considered as the 3rd person singular of the verb 'to be', there is no verb but an arbitrary one supporting hast ('is' as an existential be= exists) has neither future nor past tense and nor a negative form of its own: hast is just a single untouchable lexeme. It needs no other linguistic element to be complete (Hast. is a complete sentence meaning "s/he it exists"). In fact, any manipulation of the arbitrary verb, e.g. its conjugation, turns hast back into a copula.

Eventually from such linguistic analyses, it appears that while astī (is-ness) would resemble the world of Heraclitus, hastī (existence) would rather approaches a metaphysical concept resembling the Parmenidas's interpretation of existence.

In this regard, Avicenna, who was a firm follower of Aristotle, could not accept either Heraclitian is-ness (where only constant was change), nor Parmenidean monist immoveable existence (the hastī itself being constant). To solve the contradiction, it so appeared to Philosophers of Islamic world that Aristotle considered the core of existence (i.e. its substance/essence) as a fixed constant, while its facade (accident) was prone to change. To translate such a philosophical image into Persian it is like having hastī (existence) as a unique constant core covered by astī (is-ness) as a cloud of ever-changing relationships. It is clear that the Persian language, deconstructs such a composite as a sheer mirage, since it is not clear how to link the interior core (existence) with the exterior shell (is-ness). Furthermore, hast cannot be linked to anything but itself (as it is self-referent).

The argument has a theological echos as well: assuming that God is the Existence, beyond time and space, a question is raised by philosophers of the Islamic world as how he, as a transcendental existence, may ever create or contact a world of is-ness in space-time.

However, Avicenna who was more philosopher than theologian, followed the same line of argumentation as that of his ancient master, Aristotle, and tried to reconcile between ast and hast, by considering the latter as higher order of existence than the former. It is like a hierarchical order of existence. It was a philosophical Tower of Babel that the restriction of his own mother tongue (Persian) would not allow to be built, but he could maneuver in Arabic by giving the two concepts the same name wujud, although with different attributes. So, implicitly, astī (is-ness) appears as ممکن الوجود "momken-al-wujud" (contingent being), and hastī (existence) as واجب الوجود "wājeb-al-wujud" (necessary being).

On the other hand, centuries later, Sadrā, chose a more radical route, by inclining towards the reality of astī (is-ness), as the true mode of existence, and tried to get rid of the concept of hastī (existence as fixed or immovable). Thus, in his philosophy, the universal movement penetrates deep into the Aristotelian substance/essence, in unison with changing accident. He called this deep existential change حرکت جوهری harekat-e jowhari (Substantial Movement). In such a changing existence, the whole world has to go through instantaneous annihilation and recreation incessantly, while as Avicenna had predicted in his remarks on Nature, such a universal change or substantial movement would eventually entail the shortening and lengthening of time as well which has never been observed. This logical objection, which was made on Aristotle's argumentation, could not be answered in the ancient times or medieval age, but now it does not sound contradictory to the real nature of Time (as addressed in relativity theory), so by a reverse argument, a philosopher may indeed deduce that everything is changing (moving) even in the deepest core of Being.

Being in the Age of Reason

Although innovated in the late medieval period, Thomism was dogmatized in the Renaissance. From roughly 1277 to 1567, it dominated the philosophic landscape. The rationalist philosophers, however, with a new emphasis on Reason as a tool of the intellect, brought the classical and medieval traditions under new scrutiny, exercising a new concept of doubt, with varying outcomes. Foremost among the new doubters were the empiricists, the advocates of scientific method, with its emphasis on experimentation and reliance on evidence gathered from sensory experience. In parallel with the revolutions against rising political absolutism based on established religion and the replacement of faith by reasonable faith, new systems of metaphysics were promulgated in the lecture halls by charismatic professors, such as Immanuel Kant, and Hegel. The late 19th and 20th centuries featured an emotional return to the concept of existence under the name of existentialism. These philosophers were concerned mainly with ethics and religion. The metaphysical side became the domain of the phenomenalists. In parallel with these philosophies Thomism continued under the protection of the Catholic Church; in particular, the Jesuit order.

Empiricist doubts

Rationalism and empiricism have had many definitions, most concerned with specific schools of philosophy or groups of philosophers in particular countries, such as Germany. In general rationalism is the predominant school of thought in the multi-national, cross-cultural Age of reason, which began in the century straddling 1600 as a conventional date, empiricism is the reliance on sensory data gathered in experimentation by scientists of any country, who, in the Age of Reason were rationalists. An early professed empiricist, Thomas Hobbes, known as an eccentric denizen of the court of Charles II of England (an "old bear"), published in 1651 Leviathan, a political treatise written during the English civil war, containing an early manifesto in English of rationalism.

Hobbes said:

"The Latines called Accounts of mony Rationes ... and thence it seems to proceed that they extended the word Ratio, to the faculty of Reckoning in all other things....When a man reasoneth hee does nothing else but conceive a summe totall ... For Reason ... is nothing but Reckoning ... of the consequences of generall names agreed upon, for the marking and signifying of our thoughts ...."

In Hobbes reasoning is the right process of drawing conclusions from definitions (the "names agreed upon"). He goes on to define error as self-contradiction of definition ("an absurdity, or senselesse Speech") or conclusions that do not follow the definitions on which they are supposed to be based. Science, on the other hand, is the outcome of "right reasoning," which is based on "natural sense and imagination", a kind of sensitivity to nature, as "nature it selfe cannot erre."

Having chosen his ground carefully Hobbes launches an epistemological attack on metaphysics. The academic philosophers had arrived at the Theory of Matter and Form from consideration of certain natural paradoxes subsumed under the general heading of the Unity Problem. For example, a body appears to be one thing and yet it is distributed into many parts. Which is it, one or many? Aristotle had arrived at the real distinction between matter and form, metaphysical components whose interpenetration produces the paradox. The whole unity comes from the substantial form and the distribution into parts from the matter. Inhering in the parts giving them really distinct unities are the accidental forms. The unity of the whole being is actuated by another really distinct principle, the existence.

If nature cannot err, then there are no paradoxes in it; to Hobbes, the paradox is a form of the absurd, which is inconsistency: "Natural sense and imagination, are not subject to absurdity" and "For error is but a deception ... But when we make a generall assertion, unlesse it be a true one, the possibility of it is inconceivable. And words whereby we conceive nothing but the sound, are those we call Absurd ...." Among Hobbes examples are "round quadrangle", "immaterial substance", "free subject." Of the scholastics he says:

"Yet they will have us beleeve, that by the Almighty power of God, one body may be at one and the same time in many places [the problem of the universals]; and many bodies at one and the same time in one place [the whole and the parts]; ... And these are but a small part of the Incongruencies they are forced to, from their disputing philosophically, instead of admiring, and adoring of the Divine and Incomprehensible Nature ...."

The real distinction between essence and existence, and that between form and matter, which served for so long as the basis of metaphysics, Hobbes identifies as "the Error of Separated Essences." The words "Is, or Bee, or Are, and the like" add no meaning to an argument nor do derived words such as "Entity, Essence, Essentially, Essentiality", which "are the names of nothing" but are mere "Signes" connecting "one name or attribute to another: as when we say, "a man is a living body", we mean not that the man is one thing, the living body another, and the is, or being a third: but that the man, and the living body, is the same thing; ..." Metaphysiques, Hobbes says, is "far from the possibility of being understood" and is "repugnant to natural reason."

Being to Hobbes (and the other empiricists) is the physical universe:

The world, (I mean ... the Universe, that is, the whole masse of all things that are) is corporeall, that is to say, Body; and hath the dimension of magnitude, namely, Length, Bredth and Depth: also every part of Body, is likewise Body ... and consequently every part of the Universe is Body, and that which is not Body, is no part of the Universe: and because the Universe is all, that which is no part of it is nothing; and consequently no where."

Hobbes' view is representative of his tradition. As Aristotle offered the categories and the act of existence, and Aquinas the analogy of being, the rationalists also had their own system, the great chain of being, an interlocking hierarchy of beings from God to dust.

Idealist systems

In addition to the materialism of the empiricists, under the same aegis of Reason, rationalism produced systems that were diametrically opposed now called idealism, which denied the reality of matter in favor of the reality of mind. By a 20th-century classification, the idealists (Kant, Hegel and others), are considered the beginning of continental philosophy, while the empiricists are the beginning, or the immediate predecessors, of analytical philosophy. 

Being in continental philosophy and existentialism

Some philosophers deny that the concept of "being" has any meaning at all, since we only define an object's existence by its relation to other objects, and actions it undertakes. The term "I am" has no meaning by itself; it must have an action or relation appended to it. This in turn has led to the thought that "being" and nothingness are closely related, developed in existential philosophy.

Existentialist philosophers such as Sartre, as well as continental philosophers such as Hegel and Heidegger have also written extensively on the concept of being. Hegel distinguishes between the being of objects (being in itself) and the being of people (Geist). Hegel, however, did not think there was much hope for delineating a "meaning" of being, because being stripped of all predicates is simply nothing.

Heidegger, in his quest to re-pose the original pre-Socratic question of Being, wondered at how to meaningfully ask the question of the meaning of being, since it is both the greatest, as it includes everything that is, and the least, since no particular thing can be said of it. He distinguishes between different modes of beings: a privative mode is present-at-hand, whereas beings in a fuller sense are described as ready-to-hand. The one who asks the question of Being is described as Da-sein ("there/here-being") or being-in-the-world. Sartre, popularly understood as misreading Heidegger (an understanding supported by Heidegger's essay "Letter on Humanism" which responds to Sartre's famous address, "Existentialism is a Humanism"), employs modes of being in an attempt to ground his concept of freedom ontologically by distinguishing between being-in-itself and being-for-itself.

Being is also understood as one's "state of being," and hence its common meaning is in the context of human (personal) experience, with aspects that involve expressions and manifestations coming from an innate "being", or personal character. Heidegger coined the term "dasein" for this property of being in his influential work Being and Time ("this entity which each of us is himself…we shall denote by the term 'dasein.'"), in which he argued that being or dasein links one's sense of one's body to one's perception of world. Heidegger, amongst others, referred to an innate language as the foundation of being, which gives signal to all aspects of being.