One of the prevailing topics in philosophy has been free will, and few figures have been as important in the study of free will than Thomas Aquinas. The thinker offered a number of explanations about free will, how human beings conceive of it, and whether it is truly free. To understand Aquinas on this topic, one must understand his spirited defenses for free will as a concept. He begins with the assumption that the will is free, but he does not stop there. He explains over and over why he makes this assumption, arguing about the nature of reality and how the human psyche interacts with that reality. The thinker makes keen observations not only about his own thoughts, but about his place in the physical world and how he interacts with it. To him, will is free, and everything around him suggests the truth of this assertion.

In explaining his assumption that the will is free, Aquinas notes that an appetite or desire follows every single form, meaning that when a person gains some new knowledge, there is always an appetite for more. From this, Aquinas posits two different appetites—one based upon the senses and one based principally upon the intellectual. Aquinas notes that human beings tend to follow each of these in some way, accounting for both the intellectual pull and the gut feeling that many describe when discussing their decision-making protocols. For Aquinas, maintaining this understanding of himself and how his psyche relates to the known world is central to understanding his own free will and the free will of all human beings.

Aquinas’s theories on free will are powerfully linked to the concept of necessity. His work posits the question of whether a person is truly free when there are necessities that happen all around him. He looks principally at four different kinds of necessity. This leads him in part to an understanding of how different kinds of beings utilize judgment and instinct. Animals, he will argue, do not operate with free will because their behavior is out of necessity. A brute animal discovering that an apex predator is in his path is not operating with free will, but rather, is being guided by an intrinsic force that reveals to it that being around the animal is principally a bad thing in nature. Human beings, Aquinas argues, are different because they operate with a sense of judgment. By this, he is suggesting that any number of situations, human beings are presented with different options and have the ability to make a choice. That choice is what constitutes free will, since there was no intrinsic necessity driving the person to make the choice in question. If a man can take any number of different courses and yet he retains the ability to recognize this and go down a certain path, then the man operates in free will rather than the contrived experience of instinctual inclination.

Importantly, the author links free will with reason. Aquinas believes strongly that all men have the ability to operate with reason. Reason without free will, though, is meaningless. This leads on to the thinker’s beliefs on the nature of rationality. Reason is simply the process by which one makes important choices. The thinking portion is only one part of that, but people are capable of deciphering their actions at the end of their thinking process. If people could not make choices after going through a specific process of rationality and problem solving, then reason would be useless and non-existence in nature. Aquinas operates on the assumption that human beings maintain rationality. Because he believes free will to be a necessary component of rationality, and he sees evidence that human beings occasionally make rational choices when presented with options and fact, Aquinas must conclude that free will is a real and powerful force, impacting the world around him in unique ways.

Aquinas recognizes the differences between a voluntary action and a non-voluntary action in human beings. Some acts, he notes, are voluntary, and once they get started, a person is operating largely on autopilot or instinct. For instance, a person does not actively tell himself how to turn a car through every motion of this particular action. It is largely instinct and training that come into play, as a person’s muscles perform the activity needed to shift the wheel and send the car going in another direction. What Aquinas does believe, however, is that human beings are the actors that set in motion the process by which these voluntary acts come about. If human beings are making rational choices to engage their sub-conscious instinct, then human beings retain the free will in the matter. It is as if human beings hit a button to power on these inclinations, understanding that they are inclinations and thus can make life easier. In the view of Aquinas, this does not undermine the nature of free will in humans, but actually enhances it because it presents yet another way in which human beings decide their own outcomes.

Ultimately Aquinas seeks to separate humans from animals on the basis of rationality and the control. He defines free will as a thinking beyond necessity and instinct. He believes that human beings behave with a certain level of rational thought, and as a consequence of this, they make decisions on their own volition outside of the control of their intrinsic forces.