Aquinas' First Cause Argument
Thomism Builds on the Platonic and Aristotelian Traditions
Mar 7, 2008
Thomas Aquinas’ philosophy owes a lot to Aristotle, and therefore to Plato. He uses the Aristotelian concept of substance to develop a rational basis for theology. For Aristotle, substance is what exists of itself, not depending on anything else for it to exist. For example, colours depend on the object in which they inhere for their existence, but not vice-versa. But how can this hidden substance of things be explained?
The Search for Causes
What is the ultimate reality behind appearances; is it perhaps matter or mind? Aquinas says that some ‘thing’ bringing itself into existence is impossible, and so we must look for the cause of each thing's existence in something prior to itself. Humans derive their lives from their parents’ reproduction, as do lesser animate organisms such as trees. But this backward chain cannot go on forever. If it did, there would be an infinity of time in the past. This would mean there would need to have been a forward movement in time by an infinite amount just to get here in the first place. But, it is not possible to get to the end of an infinite amount of time, or else it wouldn't be infinite, so since there is a 'here now', there must have been a first cause at the beginning of time.
What Would Be a First Cause?
What is the first cause? The Big Bang? Aquinas' position implies that even if there was a Big Bang, that couldn't be the first cause, because the next obvious question would be: what happened to cause the Big Bang? No physical event or object could answer this question, because all occurrences and physical beings are what Aquinas calls contingent - things that only happen because something else happened first, and might not have happened to exist at all. They do not have substance in the ultimate sense of that word. But everything in the universe is like this, is contingent, because everything physical is limited within the causal chain of the space-time continuum. Therefore, if there needs to be a first cause which actually begins time, it must exist outside of space and time. If there is a first cause, therefore, Aquinas maintains, it must be non-physical and atemporal (or eternal). This is the concept that Aquinas says all call God.
Does God Need a Cause?
Aquinas avoids the problem of ‘what caused God?’ by suggesting that ‘every being which is not the act of existing alone has a cause of its existence’ whereas the first cause should be conceived as ‘simply the act of existing’ itself. Aquinas distinguishes the first cause as a Being in a universal sense, without physical attributes, and being therefore essentially different from every individual act of existing. This is similar to how Plato talks about the existence of the Forms. Aquinas also concludes that the Being that first causes all other beings must possess within ‘all perfections of all genera of beings; so He is said to be unqualifiedly perfect.’
God as First Cause Provides a Framework to Scientific Truth
With this explanation of Aquinas', God is understood to be the mysterious first cause, whose existence transcends space-time, and whose Being explains all other beings. Without this explanation, there is a need to come up with a better ultimate explantion for all that is, including space and time.
Source: Thomas Aquinas, Selected Philosophical Writings (ed. Timothy McDermott), Oxford University Press, Oxford, 1998
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