Cause and effect
Most of us think that all effects come from a cause. Yes, each effect must have a cause inevitably. It is because a cause is a relation term of an equation.
However, this doesn't prove that all beings are presented by causes. Although all things have a cause necessarily, if there are some things that lack causes, those are thought that they existed before creation by themselves.
Though human beings sometimes deny causes, they have some objects that they think exist clearly. It is surely contradiction. What is produced without causes and what exists without causes don't recognize them as original causes.
In the case we rule out all external causes, we also should rule out all created things. It is certain that the absolute being isn't its own cause. All things that were created without causes were produced from nothing. In other words, objects that were produced without causes are nothing from causes.
However, as nothing can't be something and it can't be a cause, we should perceive that all objects have their own actual causes of being.
Therefore, all things that have started to exist should have the causes of being.