The reason why I ask is because the law of cause and effect is central to scienctific investigation, yet I've only heard that causes necessitate effects and all effects have a cause.

But it seems to me that this could go deeper, much deeper. Like what if you have two effects of the same cause or two causes of the same effect, how would you know? How do you know that you have a cause-effect relationship, and how do you know if something merely seems to be a cause-effect relationship, but is not?

I've tried searching for this on Google, but the results returned are sketchy at best, as they subscribe to what one may call pseudo-science (for e.g, every 'good cause' brings about a 'good effect', or something else to do with karma, which I personally commit to the flames).

Thank you in advance.

  • 1
    Youi can see The Metaphysics of Causation with biblio. May 5, 2017 at 10:21
  • 1
    See also Causality in Science and Mechanisms in Science
    – Conifold
    May 5, 2017 at 18:08
  • It has to do with the 'arrow of time'. Because time runs forwards, cause always precedes effect. only free will would seem to produce effects without cause. However, from a purely physical standpoint, i cannot randomly choose to kill someone who is already dead. And many physicists believe free will may be a cruel illusion.
    – Richard
    May 9, 2017 at 12:54
  • i find the subject interesting, but the question is quite broad, though obviously in a sympathetic way, as you've tried google
    – user25714
    May 12, 2017 at 19:39
  • Cause and effect are a bit different in physics. Two events are intrinsically correlated because of the laws they follow; but it is somewhat arbitrary to call the event that occurs first the 'cause' and the subsequent event the 'effect'. Really, both are necessary consequences of each other. If time was reversed the laws would still be valid, but the label of 'cause' and 'effect' would be switched. Jun 12, 2017 at 0:24

4 Answers 4


Your question is unclear. You're dissatisfied with "causes necessitate effects" and "all effects have a cause," but you don't explain why. You do point to some problems that concern you ("two effects of the same cause," "two causes of the same effect," something like correlation vs. causation), though you present them so briefly that it's hard to tell what you already know about the topic or how you're thinking about these problems. (It's also not clear to me what they have to do with "causes necessitate effects" and "all effects have a cause.") Since it's not clear what you're asking, it's hard to give a good answer.

So let me recommend a few major ideas on causation from academic philosophy. Maybe doing some more reading on the topic will help you refine your question.

First, Mackie's "Causes and Conditions". Mackie proposed that causes can be understood as INUS conditions: insufficient but necessary conditions for some sufficient but not necessary condition for the effect. For example, a spark by itself won't light a candle — there might not be oxygen in the air to burn. So the spark is insufficient to light the candle; but it is necessary for a complex condition (the presence of both the spark and oxygen close to the candle wick, sheltered from the wind, etc.) that is sufficient for the candle to light. However, this complex condition is not necessary for the candle to light: some other complex (involving touching the wick with an already-burning flame rather than a spark, for example) would also be sufficient. Mackie's account takes care of one of the problems with the idea that "causes necessitate effects"; namely, that sometimes you can have the cause without the effect. Again, if there's no oxygen, the spark won't light the candle. Mackie's account also takes care of cases where there are two (or more) causes of the same effect: both oxygen and the spark are causes of the candle lighting.

Another major innovation is probabilistic causation. This is another way to deal with the problem of causes that don't necessitate effects. Consider smoking and lung cancer. Not everyone who smokes develops lung cancer; but smoking is associated with a large increase in probability or risk of developing lung cancer. Roughly, according to probabilistic theories of causation, X is a cause of Y if and only if X increases the probability of Y.

A third important idea is interventionist or manipulationist accounts of causation. These accounts are designed to tackle the problem of distinguishing correlation and causation. Suppose X and Y are correlated. Basically, if (a) when we manipulate or change the value of X, Y also changes value; and (b) when we manipulate or change the value of Y, X does not change value; then we can say that X causes Y. This is the basic logic of a scientific experiment: we change the value of one variable, and look to see if there are also changes in the other variable.


...what if you have two effects of the same cause or two causes of the same effect, how would you know?

John Stuart Mill put a lot of thought into this question. He identified five methods to isolate causes and effects. A System of Logic...and the Methods of Scientific Investigation (1889) (Project Gutenberg 2009), p.280-89. Here is the First Canon:

If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstance in which alone all the instances agree, is the cause (or effect) of the given phenomenon.

Combined, the canons permit analysis of complex data. For example, here is the Third Canon:

If two or more instances in which the phenomenon occurs have only one circumstance in common, while two or more instances in which it does not occur have nothing in common save the absence of that circumstance, the circumstance in which alone the two sets of instances differ, is the effect, or the cause, or an indispensable part of the cause, of the phenomenon.

By repeated observations, the canons enable solutions to such events as multiple effects from a single cause, or multiple causes behind a single effect.


I'm not sure if this is exactly what you're looking for, perhaps some will help.

Cum hoc ergo propter hoc "With this, therefore, because of this". Post hoc ergo propter hoc " After this therefore because of this".

Can B happen before A Is a questionable cause, a logical fallacy.

The "effect" ceases to be the effect if there is no "cause", as there is no proper definition to properly define it as such.
It inturn becomes the cause, or just stagnant.
No clouds means no rain, But do you believe no clouds is the reason for no rain? Hume added a component to casualty that is expectancy, you can expect A will cause B given the experience has happened before. Expecting a Effect of a cause is substantial in recognizing what is A and which is B and also you can manipulate a outcome, turn A into a C.

Retro-causality Is a hypothetical arguement Reversing cause and effect Allowing effect to happen before cause. It is primarily a thought experiment. Can the future effect our present?

Cause means responsible, The definitions of these words do not change and they can not be manipulated. As I stated above once B happens first It fails to live up to its proper definition.

Cause and effect, action and reaction are dependant upon their places and when compromised fail to be.

The nine different criteria of causation

  1. Strength of the association
  2. Consistency, is it testable
  3. Specificity
  4. Temporality, cart before the horse, the cause must proceed the effect.
  5. Biological gradient, in what way does the effect depend on the cause varible?
  6. Plausibility, is there a likely explination for causation?
  7. Coherence, would causation contridict established facts?
    1. Experiment, does manipulation of cause affect the effect?
  8. Analogy, is there a past precedence?

Correlation by defintion implies a relationship between two or more things. How they interact or conclude, is primarily in direct relation to the objects or events.

This subject is expansive with disciplines In physics, Mathmatics, philosophy and even moral conduct.


If you ask the question to a former age, prior to our own epoch, it would be shown that the concept of causality is baseless. Many old books of philosophy, before the Analytic takeover, show this in detail, argue it out.

The crude gist is that the sine qua non cause, the immediate cause, is conditioned, ultimately by the whole universe at a particular moment. Usually, when one speaks of the proximate causes, the things necessary to let something happen, one takes almost everything for granted, example, gravity. This is one of the central issues in philosophy proper, which is to say, not Analytic Philosophy nor any other qualified form of philosophy which is often what one is trained in these days. That amounts to saying that the training is about philosophy of science, however, in the decisive respect philosophy proper no longer exists.

The training is lacking. It has a diminished afterlife in Literary Theory and so-called Continental Philosophy and the mentioned Analytic Philosophy/Philosophy of Science (and many other fields). I make these remarks to explain why the issue is very much obscured and turbid. If you like I will delineate the main points of these modern developments which are decisive for the future of all life on the earth.

For now I will simply point you to Hume and Kant, which is the crux of the modern issue. The Kantian formula is: (efficient) cause is not derivable from the concept of a thing, but it is a necessary inference. That is the famous so-called Synthetic a priori.

In the sciences, what happened is Comte took over efficient cause and let it become mathematical function. I.e., he set cause aside, and let function come in. Function is not sensu stricto subject to the Problem of Induction, but rather to a similar but subtly different restraint.

That didn't really solve the problem, but basically, these days, it still stands. Physics speaks of functions, not causes. Since about the twenties of the last century, quantum physics gave up the claim that it could derive everything with respect to the unified development, so-called, of the particle of the quantum states as a 'function of the past'. Randomness, and something worse and more unintelligible than randomness, came in sometime later.

Philosophically speaking, cause became effect, i.e., power. I would say Hobbes gives the crucial statements on effect, which lead into Leibniz and then Nietzsche's Will to Power. Given that this site is mostly keyed in to Analytic Philosophy I leave off giving details that would likely be unappreciated and not understood by those lacking in the requisite training.


That which count as the crucial issues depend greatly on one's background, so far as we regard the issue in terms of what will be interesting to the reader. And not by a higher or more worthy criterion.

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