There are many philosophical issues with the existence of God. Some definitions of God are not specific. Arguments for the existence of God typically include metaphysical, empirical, inductive, and subjective types. Some theories are built around holes in evolutionary theory, as well as order and complexity in the world. Arguments against the existence of God typically include empirical, deductive, and inductive arguments. Conclusions sometimes include: "God does not exist" (strong atheism); "God almost certainly does not exist" ("de facto" atheism); "no one knows whether God exists" (agnosticism); "God exists, but this cannot be proven or disproven" (deism or theism); and "God exists and this can be proven" (theism). There are many variations on these positions, and sometimes different names for some of them. For example, the position "God exists and this can be proven" is sometimes called "gnostic theism" or "strong theism".