Events can be spontaneous or non spontaneous. Spontaneous is defined as occurring without apparent external cause. Non spontaneous events are causal, that is, there is cause and effect.

Suppose an event occurs, for example alpha decay, then is it possible to conclude that the event was partially spontaneous and partially causal at the same time? If yes, what are some examples of partially spontaneous and partially causal events? What will be the nature of such an event if it occurs?

Can I call such an event as coincidentally spontaneous?

  • For me it looks a bit like making concepts unnecessarily complicating. I assume that you understand "cause" as "sufficient cause". Then the two terms "spontanously" and "having a cause" are mutually excluding.
    – Jo Wehler
    Nov 2, 2023 at 8:02
  • "Events", "spontaneous", "external", "cause", etc. are all mental constructs (metaphysical perspective). When you say "cause: break pedal pushed; consequence: car stops", you are making a very complex rational abstraction of the world. Physically, there are only atoms/fields out there (physical perspective). So, the answers are yes/no/partially, depending on the subjective perspective you select: physical/metaphysical/mixed.
    – RodolfoAP
    Nov 2, 2023 at 8:19
  • @RodolfoAP There is black matter and black energy as well. Nov 2, 2023 at 9:04
  • Worth noting that in physics, spontaneous has a different definition - something is spontaneous if it will happen on its own on their own given the initial conditions of the system. A ball on a slope with initial velocity 0 spontaneously rolls down the slope; a ball in a bucket glued to a slope needs an external input of energy (to get out of the bucket) in order to roll down the slope.
    – g s
    Nov 4, 2023 at 0:58

2 Answers 2


It depends on how you interpret your terminology. A phenomenon, such as fog, say, might considered to have multiple causes, in that several factors must be present for it to form. Also, there is a difference between a cause and a root cause, the latter being an event further down the chain of events leading to an outcome, rather than the final trigger event. If you are happy with the idea of multiple causes, and you are prepared to consider that a cause maybe an event earlier than a final tigger event, then yes a phenomenon can be partly spontaneous. To take a contrived example, suppose a Geiger counter with an electrical fault goes on fire when it detects a radioactive decay event. You might say that the fire was caused partly by the fault and partly by the spontaneous decay event.

  • Great example towards the end! Causes usually refer to the event immediately prior though, so arguably the cause would not be spontaneous. However, this seems purely semantic. Nov 4, 2023 at 1:26

It would depend on how you define cause. Some argue that it is merely a condition that is necessary for an effect to occur. Most, when they think of a cause, think of a necessary condition that is sufficient in explaining the effect. Some others argue that causes don’t exist within the universe. Every form of matter and energy, after all, is just a rearrangement of the last, so where does a cause come in?

With all this being said, I think with respect to your question, a cause is a reason that sufficiently explains an effect. As such, no, I do not think that you can have a partial cause or partial spotaneity. A spontaneous effect is by definition without cause and vice versa.

The conditions that lead to radioactive decay may have no cause but the exact point at which it decays does not have a (local and deterministic) cause, atleast according to quantum mechanics.

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