This article is about causality as it is used in many different fields. For its use specifically in physics, see causality (physics).
For the use of effect in music (audio effect), see sound effect and effects pedals.

The philosophical concept of causality or causation refers to the set of all particular "causal" or "cause-and-effect" relations. A neutral definition is notoriously hard to provide since every aspect of causation has received substantial debate. Most generally, causation is a relationship that holds between events, objects, variables, or states of affairs. It is usually presumed that the cause chronologically precedes the effect. Finally, the existence of a causal relationship generally suggests that, all things equal, if the cause occurs the effect will as well (or at least the probability of the effect occuring will increase).

Examples describing causal relationships:

  • The cue ball coliding with the eight ball causes the eight ball to roll into pocket.
  • The presence of Heat causes water to boil.
  • The Moon's gravity causes the Earth's tides.
  • A hard blow to the arm causes a bruise.
  • My pushing the accelerator caused the car to go faster.

Causality contrasted with logical implication

Logical conditional statements are not statements of causality. Since logical conditional statements and causal statements are both presented using "If...then..." in English they are commonly confused; they are distinct, however. The standard conditional statement expresses a fact about the actual world, while causal statements imply something more. For example all of the following statements are true (interpreting "If... then..." as the logical conditional):

  • If George Bush was president of the United States in 2004, then Germany is in Europe
  • If George Washington was president of the United States in 2004, then Germany is in Europe
  • If George Washington was president of the United States in 2004, then the Moon is made of green cheese

The first is true since both the antecedent and the consequent are true. The second and third are both true because the antecedent is false. Of course, none of these statements express a causal connection between the antecedent and consequent.

Another sort of logical implication, known as counterfactual implication has a stronger connection with causality. In fact, some philosophers (most notably David Lewis) have suggested that causality can be understood entirely as counterfactual reasoning. However, not even all counterfactual statements count as examples of causality. Consider the following two statements:

  • If A is a triangle, then A has three sides.
  • If switch S is thrown, then bulb B will light.

In the first case it would not be correct to say that A's being a triangle caused it to have three sides, since the relationship between triangularity and three-sidedness is one of definition. Nonetheless, even interpreted counterfactually, the first statement is true. Most sophisticated acounts of causation find some way to deal with this distinction.

Necessary and sufficient causes

A similar concept occurs in logic, for this see Necessary and sufficient conditions

Causes are often distinguished into two types: necessary and sufficient. If x is a necessary cause of y, then y will only occur if preceeded by x. In this case the presence of x does not ensure that y will occur, but the presence of y ensures that x must have occured. On the other hand, sufficient causes guarentee the effect. So if x is a sufficient cause of y, the presence x guarentees y. However, other events may also cause y, and thus y's presence does not ensure the presence of x.

J.L. Mackie argues that usual talk of "cause" in fact refers to INUS conditions (insufficient and non-redundant parts of unneccessary but sufficient causes). For example, consider the short circuit as a cause of the house burning down. Consider the collection of events, the short circuit, the presence of oxygen, the inflamibility of the house, and the absence of firefighters. Altogether these are unnecessary but sufficient to the house's destruction (since many other collection of events certainly have destroyed the house). Within this collection, the short circuit is insufficient but non-reduendant part (since the short circuit by itself would not cause the fire, but the fire will not happen without it). So the short circuit is an INUS cause of the house burning down.


Attribution theory is the theory concerning how people explain individual occurrences of causation. Attribution can be external (assigning causality to an outside agent or force - claiming that some outside thing motivated the event) or internal (assigning causality to factors within the person - taking personal responsibility or accountability for one's actions and claiming that the person was directly responsible for the event). Taking causation one step further, the type of attribution a person provides influences their future behavior.

The intention behind the cause or the effect can be covered by the subject of action (philosophy). See also accident; blame;intent; responsibility;


According to law and jurisprudence, legal cause must be demonstrated in order to hold a defendant liable for a crime or a tort (ie. a civil wrong such as negligence or trespass). It must be proven that causality, or a 'sufficient causal link' relates the defendant's actions to the criminal event or damage in question.


In a strict reading, if A causes B, then A must always be followed by B. In this sense, sex does not cause pregnancy, nor does smoking cause cancer. In everyday usage, we therefore often take "A causes B" to mean "A results in an increase in the probability of B"; sometimes that A is a necessary but not a sufficient condition for B; and sometimes that A is one of many things that can contribute to the occurrence of B.

The establishing of cause and effect, even with this relaxed reading, is notoriously difficult, expressed by the widely accepted statement "correlation does not imply causation". For instance, the observation that smokers have a dramatically increased lung cancer rate does not establish that smoking must be a cause of that increased cancer rate: maybe there exists a certain genetic defect which both causes cancer and a yearning for nicotine.

Alternatively, A may be:

  • one of many possible causes of B,
  • a single step along a causal chain (sex often leads to release of sperm, which can lead to the combination of sperm and egg, and the combination sperm and egg leads to pregnancy)
  • one of many factors which, when combined, lead to B

Another complication is typified by the example of the moon's gravity. It isn't accurate to say, "the moon exerts a gravitic pull and then the tides rise." Gravity, rather, is a law expressing a constant observable relationship among masses, and the movement of the tides is an example of that relationship. There are no discrete events or "pulls" that can be said to precede the rising of tides.

Our view of causation depends on what we consider to be the relevant events. Another way to view the statement, "Lightning causes thunder" is to see both lightning and thunder as two perceptions of the same event, viz., an electric discharge that we perceive first visually and then aurally.


Aristotle suggested four types of cause for a thing which exists: Material, Efficient, Final and Formal.

Take for example the causality involved in creating a silver chalice used in a religious ceremony (this example is from Martin Heidegger). The four causes of the event of its creation are:

  • The material cause would be the silver used to create the chalice; the raw matter required by the event.
  • The formal cause would be the chalice design itself—the shape in which to form the silver; the design for the use of the raw matter.
  • The efficient cause would be the silversmith who took the silver and formed it into shape of the chalice; the actual agent required in turning the raw matter into the desired form.
  • The final cause would be the religious ceremony which required a silver chalice in the first place; the ultimate reason behind the event, what compels the agent to make the raw matter into its form.

Note that cause here does not imply a temporal relation between the cause and the effect. See supervenience.


The philosopher who produced the most striking analysis of causality was David Hume. He asserted that it was impossible to know that certain laws of cause and effect always apply - no matter how many times one observe them occurring. Just because the sun has risen every day since the beginning of the Earth does not mean that it will rise again tomorrow. However, it is impossible to go about one's life without assuming such connections and the best that we can do is to maintain an open mind and never presume that we know any laws of causality for certain. This was used as an argument against metaphysics, ideology and attempts to find theories for everything. A.J. Ayer claimed that his law of verification was an application of Hume's teaching, yet it was, in fact, exactly what Hume argued against - assuming that empirical observation could lead to definite knowledge. Karl Popper clarified matters with his law of falsification, which is more in line with Hume's teachings that any new experience could disprove a law that had been previously thought to be certain.

Causality, nihilism, and existentialism

Nihilists subscribe to a deterministic world-view in which the universe is nothing but a chain of meaningless events following one after another according to the law of cause and effect. According to this worldview there is no such thing as "free will", and therefore, no such thing as morality. Learning to bear the burden of a meaningless universe, and justify one's own existence, is the first step toward becoming the "▄bermensch" (English: "overman") that Nietzsche speaks of extensively in his philosophical writings.

Nietzsche's life provides an object lesson for some wary of nihilism, maintaining that such lives end quite typically in madness and chaos. Other Existentialists have suggested that people have the courage to accept that while no meaning has been designed in the universe, we each can provide a meaning for ourselves.

In light of the difficulty philosophers have pointed out in establishing the validity of causal relations, it might seem that the clearest plausible example of causation we have left is our own ability to be the cause of events. If this be so, then our concept of causation would not prevent seeing ourselves as moral agents.

Religion and theology

The existence of God

One of the classic arguments for the existence of God is known as the "Cosmological argument" or "First cause" argument. It works from the premise that every natural event is the effect of a cause. If this is so, then the events that caused today's events must have had causes themselves, which must have had causes, and so forth. If the chain never ends, then one must uphold the hypothesis of an "actual infinite," which is often regarded as problematic, see Hilbert's paradox of the Grand Hotel. If the chain does end, it must end with a non-natural or supernatural cause at the start of the natural world -- e.g. a creation by God.

Sometimes the argument is made in non-temporal terms. The chain doesn't go back in time, it goes downward into the ever-more enduring facts, and thus toward the timeless.

Two questions that can help to focus the argument are:

1) What is an event without cause?

2) How does an event without a cause occur?

Critics of this argument point out problems with it.


Karma is the belief held by some major religions that a person's actions cause certain effects in future incarnations, positively or negatively.

Reversed causality

Some modern religious movements have postulated along the lines of philosophical idealism that causality is actually reversed from the direction normally presumed. According to these groups, causality does not proceed inward, from external random causes toward effects on a perceiving individual, but rather outward, from a perceiving individual's causative mental requests toward responsive external physical effects that only seem to be independent causes. These groups have accordingly developed new causality principles such as the doctrine of responsibility assumption.


Using the Scientific method, scientists set up experiments to determine causality in the physical world. Certain elemental forces such as gravity, the strong and weak nuclear forces, and electromagnetism are said to be the four fundamental forces which are the causes of all other events in the universe.

However, the issue of to which degree a scientific experiment is replicable has been often raised but rarely addressed. The fact that no experiment is entirely replicable questions some core assumptions in science.

In addition, many scientists in a variety of fields disagree that experiments are necessary to determine causality. For example, the link between smoking and lung cancer is considered proven by health agencies of the United States government, but experimental methods (for example, randomized controlled trials) were not used to establish that link. This view has been controversial.

See also conditioning; placebo; placebo effect;


For a discussion of how causality resonates in the field of physics, see causality (physics) Perhaps the most important implication of Causality in physics is its intimate connection to the Second Law of Thermodynamics - see the fluctuation theorem.


In the field of history, the term cause has at least two meanings, often mistakenly conflated.

  • One meaning conforms to Aristotle's final cause -- as a goal or purpose. For example, the abolition of slavery became a Union goal or intended outcome for the American Civil War following the Emancipation Proclamations and so was a cause or reason to continue the war. This meaning is not what is meant by the term causality.
  • Another meaning treats historic events as agents that bring about other historic events. This is a somewhat Platonic and Hegelian view that reifies causes as ontological entities and the term causality is used sometimes in this manner. In this view, slavery is often said to have inevitably produced the American Civil War as a result. In Aristotelian terminology, this use of the term cause is closest to his efficient cause.


In statistics, it is generally accepted that observational studies (like counting cancer cases among smokers) can give hints, but can never establish cause and effect. The gold standard for causation here is the randomized experiment: take a large number of randomly selected people, divide them into two groups, force one group to smoke and prohibit the other group from smoking (ideally in a double-blind setup), then determine whether one group develops a significantly higher lung cancer rate. Obviously, for ethical reasons this experiment cannot be performed, but the method is widely applicable for less damaging experiments.

That said, under certain assumptions, parts of the causal structure among several variables can be learned from full covariance or case data by the techniques of path analysis and more generally, Bayesian networks. Generally these inference algorithms search through the many possible causal structures among the variables, and remove ones which are strongly incompatible with the observed correlations. In general this leaves a set of possible causal relations, which should then be tested by designing appropriate experiments. If experimental data is already available, the algorithms can take advantage of that as well. For nonexperimental data, causal direction can be hinted if information about time is available. This is because causes must precede their effects temporaly. This can be set up by simple linear regression models, for instance, with an analysis of covariance in which baseline and followup values are known for a theorized cause and effect. The addition of time as a variable, though not proving causality is a big help in supporting a pre-existing theory of causal direction. For instance our degree of confidence in the direction and nature of causality is much clearer with a longitudinal epidemiologic study than a cross-sectional one.

See also: supply and demand

Symbolism and causality

While the names we give objects often refer to their appearance, they can also refer to an object's causal powers - what that object can do, the effects it has on other objects or people. David Sobel and Alison Gopnik from the Psychology Department of UC Berkeley designed a device known as the blicket detector which suggests that "when causal property and perceptual features are equally evident, children are equally as likely to use causal powers as they are to use perceptual properties when naming objects". More Info (

See also

External links

Stanford Encyclopedia of Philosophy:



  • Judea Pearl: Causality, Cambridge University Press, ISBN 0521773628
  • Peter Spirtes, Clark Glymour and Richard Scheines: Causation, Prediction, and Search, MIT Press, ISBN 0262194406

de:Kausalitńt el:Αιτιότητα fi:Kausaliteetti ja:因果 lt:Priežastingumas nl:Oorzakelijkheid no:Kausalitet


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