Arguments For God
A dispute arose as to whether there are a number of proofs of the existence of God or whether all are not merely parts of one and the same proof . While all such proofs would end in the same way, by asserting the existence of God, they do not all start at the same place. St. Thomas calls them aptly Viæ: roads to the apprehension of God which all open on the same highway.
Metaphysical arguments (for)
Metaphysical arguments for the existence of God are arguments that seek to prove the logical necessity of a being with at least one attribute that only God could have.
The Cosmological argument, which argues that God must have been around at the start of things in order to be the "first cause".
The Ontological argument, based on arguments about the "being which nothing greater-than can be conceived".
The Pantheistic argument defines God as All; it is similar to monism and panentheism.
The argument from the mind-body problem postulates that it is impossible to grasp the relation of consciousness to materiality without introducing a divinity.
Empirical arguments (for)
Other arguments avail themselves of data beyond definitions and axioms. For example, some of these arguments require only that one assume that a non-random universe able to support life exists. These arguments include:
The Teleological argument, which argues that the universe's order and complexity shows signs of purpose (telos), and that it must have been designed by an intelligent designer with properties that only a god could have.
The Anthropic argument focuses on basic facts, such as our existence, to prove God.
The Moral argument argues that objective morality exists and that therefore God exists.
The Transcendental argument for the existence of God, which argues that logic, science, ethics, and other things we take seriously do not make sense if there is no God. Therefore, atheist arguments must ultimately refute themselves if pressed with rigorous consistency. By contrast, there is also a Transcendental Argument for the Non-existence of God.
The Will to Believe Doctrine was pragmatist philosopher William James' attempt to prove God by showing that the adoption of theism as a hypothesis "works" in a believer's life. This doctrine depended heavily on James' pragmatic theory of truth where beliefs are proven by how they work when adopted rather than by proofs before they are believed (a form of the hypothetico-deductive method).
Inductive arguments (for)
Inductive arguments argue their conclusions through inductive reasoning.
Another class of philosophers asserts that the proofs for the existence of God present a fairly large probability though not absolute certainty. A number of obscure points, they say, always remain. In order to overcome these difficulties there is necessary either an act of the will, a religious experience, or the discernment of the misery of the world without God, so that finally the heart makes the decision. This view is maintained, among others, by the English statesman Arthur Balfour in his book The Foundations of Belief (1895). The opinions set forth in this work were adopted in France by Ferdinand Brunetière, the editor of the Revue des deux Mondes. Many orthodox Protestants express themselves in the same manner, as, for instance, Dr. E. Dennert, President of the Kepler Society, in his work Ist Gott tot?.
Subjective arguments (for)
Subjective arguments mainly rely on the testimony or experience of certain witnesses, or the propositions of a specific revealed religion.
The witness argument gives credibility to personal witnesses, contemporary and throughout the ages. A variation of this is the argument from miracles which relies on testimony of supernatural events to establish the existence of God.
The religious or Christological argument is specific to religions such as Christianity, and asserts that for example Jesus' life as written in the New Testament establishes his credibility, so we can believe in the truth of his statements about God. An example of this argument is the Trilemma presented by C.S. Lewis in Mere Christianity.
The Majority argument argues that people in all times and in different places have believed in God, so it is unlikely that he does not exist.
Arguments grounded in personal experience
The Scotch School led by Thomas Reid taught that the fact of the existence of God is accepted by us without knowledge of reasons but simply by a natural impulse. That God exists, this school said, is one of the chief metaphysical principles that we accept not because they are evident in themselves or because they can be proved, but because common sense obliges us to accept them.
The Argument from a Proper Basis argues that belief in God is "properly basic"--that is, similar to statements such as "I see a chair" or "I feel pain." Such beliefs are non-falsifiable and, thus, neither able to be proved nor disproved; they concern perceptual beliefs or indisputable mental states.
In Germany, the School of Friedrich Heinrich Jacobi taught that our reason is able to perceive the suprasensible. Jacobi distinguished three faculties: sense, reason, and understanding. Just as sense has immediate perception of the material so has reason immediate perception of the immaterial, while the understanding brings these perceptions to our consciousness and unites them to one another. God's existence, then, cannot be proved--Jacobi, like Kant, rejected the absolute value of the principle of causality--it must be felt by the mind.
In his Emile, Jean-Jacques Rousseau asserted that when our understanding ponders over the existence of God it encounters nothing but contradictions; the impulses of our hearts, however, are of more value than the understanding, and these proclaim clearly to us the truths of natural religion, namely, the existence of God and the immortality of the soul.
The same theory was advocated in Germany by Friedrich Schleiermacher (died 1834), who assumed an inner religious sense by means of which we feel religious truths. According to Schleiermacher, religion consists solely in this inner perception, and dogmatic doctrines are inessential.
Many modern Protestant theologians follow in Schleiermacher's footsteps, and teach that the existence of God cannot be demonstrated; certainty as to this truth is only furnished us by inner experience, feeling, and perception.
Modernist Christianity also denies the demonstrability of the existence of God. According to them we can only know something of God by means of the vital immanence, that is, under favorable circumstances the need of the Divine dormant in our subconsciousness becomes conscious and arouses that religious feeling or experience in which God reveals himself to us. In condemnation of this view the oath against Modernism formulated by Pius X says: "Deum ... naturali rationis lumine per ea quae facta sunt, hoc est per visibilia creationis opera, tanquam causam per effectus certo cognosci adeoque demostrari etiam posse, profiteor." ("I declare that by the natural light of reason, God can be certainly known and therefore His existence demonstrated through the things that are made, i.e., through the visible works of Creation, as the cause is known through its effects.")