The questions pertaining to "why there is anything at all", or, "why there is something rather than nothing" have been raised or commented on by philosophers including Gottfried Wilhelm Leibniz, Ludwig Wittgenstein, and Martin Heidegger – who called it "the fundamental question of metaphysics".
Overview
The question is posed comprehensively, rather than concerning the existence of anything specific such as the universe or multiverse, the Big Bang, mathematical laws, physical laws, time, consciousness, or God. It can be seen as an open metaphysical question.
On causation
The ancient Greek philosopher Aristotle argued that everything must have a cause, culminating in an ultimate uncaused cause. (See Four causes)
David Hume argued that, while we expect everything to have a cause because of our experience of the necessity of causes, a cause may not be necessary in the case of the formation of the universe, which is outside our experience.
Bertrand Russell took a "brute fact" position when he said, "I should say that the universe is just there, and that's all."
Philosopher Brian Leftow has argued that the question cannot have a causal explanation (as any cause must itself have a cause) or a contingent explanation (as the factors giving the contingency must pre-exist), and that if there is an answer it must be something that exists necessarily (i.e., something that just exists, rather than is caused).
Philosopher William Free argues that the only two options which can explain existence is that things either always existed or spontaneously emerged. In either scenario, existence is a fact for which there isn't a cause.
Explanations
Gottfried Wilhelm Leibniz wrote:
Why is there something rather than nothing? The sufficient reason [...] is found in a substance which [...] is a necessary being bearing the reason for its existence within itself.
Philosopher of physics Dean Rickles has argued that numbers and mathematics (or their underlying laws) may necessarily exist.
Physicist Max Tegmark wrote about the mathematical universe hypothesis, which states that all mathematical structures exist physically, and the physical universe is one of these structures. According to the hypothesis, the universe appears fine-tuned for intelligent life because of the anthropic principle, with most universes being devoid of life.
Criticism of the question
Philosopher Stephen Law has said the question may not need answering, as it is attempting to answer a question that is outside a spatio-temporal setting, from within a spatio-temporal setting. He compares the question to asking "what is north of the North Pole?" Noted philosophical wit Sidney Morgenbesser answered the question with an apothegm: "If there were nothing you'd still be complaining!", or "Even if there was nothing, you still wouldn't be satisfied!"
Physics is not enough
Physicists such as Stephen Hawking and Lawrence Krauss have offered explanations that rely on quantum mechanics, saying that in a quantum vacuum state, virtual particles and spacetime bubbles will spontaneously come into existence, which is mathematically proven by physicists from Wuhan. Nobel Laureate Frank Wilczek is credited with the aphorism that "nothing is unstable." However, this answer has not satisfied physicist Sean Carroll, who argues that Wilczek's aphorism accounts merely for the existence of matter, but not the existence of quantum states, space-time or the universe as a whole.
God is not enough
Philosopher Roy Sorensen writes in the Stanford Encyclopedia of Philosophy that to many philosophers the question is intrinsically impossible to answer, like squaring a circle, and even God does not sufficiently answer it:
"To explain why something exists, we standardly appeal to the existence of something else... For instance, if we answer 'There is something because the Universal Designer wanted there to be something', then our explanation takes for granted the existence of the Universal Designer. Someone who poses the question in a comprehensive way will not grant the existence of the Universal Designer as a starting point. If the explanation cannot begin with some entity, then it is hard to see how any explanation is feasible. Some philosophers conclude 'Why is there something rather than nothing?' is unanswerable. They think the question stumps us by imposing an impossible explanatory demand, namely, 'Deduce the existence of something without using any existential premises'. Logicians should feel no more ashamed of their inability to perform this deduction than geometers should feel ashamed at being unable to square the circle."
Argument that "nothing" is impossible
The pre-Socratic philosopher Parmenides was one of the first Western thinkers to question the possibility of nothing. Many other thinkers, such as Bede Rundle, have questioned whether nothing is an ontological possibility.
Nothing - it is opposite of existing
By realizing the two possibilities only: existence or not existence we facing the problem of two primitive models. If something 'is', then it could not. The superposition of a possibility does not resolve the problem, because appears in a combination of these two primitive models (exist and do not exist). {Taken thoughts from unknown person}
The contemporary philosopher Roy Sorenson has dismissed this line of reasoning. Curiosity, he argues, is possible "even when the proposition is known to be a necessary truth." For instance, a "reductio ad absurdum proof that 1 − 1/3 + 1/5 − 1/7 + … converges to π/4" demonstrates that not converging to π/4 is impossible. However, it provides no insight into why not converging to π/4 is impossible. Similarly, even if "nothing" is impossible, asking why that is the case is a legitimate question.