Aquinas and Epistemology

Aquinas emphasized the importance of scientific knowledge (scientia) and the existence of non-scientific forms of knowledge, such as sense knowledge and knowledge of self-evident propositions. He compared faith and scientia as subjectively certain, with faith being grounded in compelling reasons and understanding why they compel belief. In contrast, scientia is grounded in rational belief that someone else has scientia or intellectual vision, such as divine faith.

For Aquinas, scientia is used analogously to science, which involves drawing conclusions from things we already know. He contrasts science as an act of inquiry with contemplation, which is a speculative activity with truth as its immediate object. Aquinas believes that scientific inquiry aims to discover a truth not already known, while contemplation aims to enjoy a truth already known.

Science can be seen as an act of inquiry and a strong argument for the truth of a proposition, known as a scientific demonstration. If a person possesses a scientific demonstration of a proposition, they understand an argument that is logically valid and knows with certainty that the premises are true.

Aquinas recognizes the Aristotelian sense of scientia as an intellectual habit or disposition that involves the possession of scientific demonstrations and knowledge about a subject matter. This habit is more than the fruit of inquiry and the possession of arguments; it involves knowing the basic facts, principles, causes, and logical connections between these facts. A person with a science of a subject has systematic and controlled knowledge, allowing them to speak about it with ease, coherence, clarity, and profundity.

Aquinas notes that the first principles of a science are sometimes naturally known by the scientist, but sacred theology does not fit this characterization of science. The first principles of sacred theology are articles of faith, not known by the natural light of reason but by the grace of God. However, contemporary philosophers of science would not find sacred theology's inability to fit neatly into a well-defined univocal conception of science a problem for its scientific status.

Sacred theology draws on principles known by those with a higher science, in this case, the science possessed by God and the blessed. Despite not being known by the natural light of reason, sacred theology is still a science, as those who possess such a science can draw logical conclusions from the articles of faith, argue that one article of faith is logically consistent with other articles of faith, and answer objections to the articles of faith.

Aquinas' understanding of science is more restrictive than contemporary notions, as he believes that we know something scientifically only if our knowledge of it is certain. This is based on demonstrative knowledge, which begins from premises we know with certainty by way of reflection upon sense experience. However, modern notions of science often make claims of science fallible and uncertain.

In his philosophy of science, Aquinas believes that the most capacious scientific account of a physical object or event involves mentioning its four causes: efficient, material, formal, and final causes. He believes that material objects, whether natural or artificial, have four causes: material cause (what O is made of), formal cause (what O is), final cause (what the end, goal, purpose, or function of O is), and efficient cause (what brings or conserves O in(to) being).

The Efficient Cause is a being that acts to bring or conserve a feature F in x. Aquinas thinks that there are different kinds of efficient causes, such as God being the primary efficient cause of any created being and creatures being secondary efficient causes. God is the primary efficient cause as creator ex nihilo, while creatures are secondary efficient causes in the sense that they work on pre-existing matter such that matter that is merely potentially F actually becomes F.

In conclusion, Aquinas' philosophy of science is more restrictive than contemporary notions, but it is still a valuable perspective on the nature of knowledge and the role of the four causes in understanding and addressing the world.

Aquinas's concept of "material cause" is crucial for understanding change and the subject of change. He believes that the material cause for a substantial change is prima materia (prime or first matter), which is the intrinsic cause of a substance that can undergo substantial change. Aquinas believes that substances are unified objects of the highest order, and if substantial changes had actual substances functioning as the ultimate subjects, then it would be reasonable to question the substantial existence of those substances.

Prime matter is the ultimate material cause of a substance that can undergo substantial change, and it never exists without being configured by some form. Matter always exists under dimensions, and this prime matter is configured by the accidental form of quantity, specifically the accidental quantity of existing in three dimensions. It is never the case that some prime matter exists without being configured by some substantial form.

The theoretical significance of the view that material substances are composed of prime matter as a part is that prime matter is the material causal explanation of the fact that a material substance's generation and potential corruption are changes that are real, substantial, natural, and intelligible. For example, a quantity of prime matter might be configured by the substantial form of an insect, living cells, chemical compounds, or incorporated into the body of a frog.

Aquinas's formal cause can be understood in three ways: the nature or definition of a thing, intrinsic to or inheres in a substance, and the pattern or definition of a thing insofar as it exists in the mind of the maker. He believes that all substances have final causes, but not all substances have functions.

For Aquinas, the formal cause of a substance is the end, goal, purpose, or function of the object. For example, a knife has the function of cutting, while the heart has the purpose of pumping blood. Aquinas thinks that all substances have final causes, but not all final causes are functions. For example, clouds do have final causes, but not in the same way as artifacts or parts of organic wholes.

In the broadest sense, the final cause of an object is an inclination or tendency to act in a certain way, bringing about a certain range of effects. For example, a knife is something that tends to cut, and a cloud is a substance that tends to interact with other substances in the atmosphere in certain ways.

In summary, Aquinas' formal cause can be understood in three ways: the nature or definition of a thing, the intrinsic form of a substance, and the final cause of an object.

Aquinas' philosophical psychology focuses on the final cause, which is the cause of all causes. He believes that an object's tendency to act in a certain way requires a certain formal cause, such as being a thing of a certain kind and composed of certain sorts of stuffs and organs. Some final causes are intrinsic, meaning that every substance tends to act in a certain way, given its nature. However, some final causes are extrinsic, meaning that an object acts as an efficient cause of an effect partly due to the final causality of an object extrinsic to it.

Aquinas also recognizes different kinds of knowledge, such as sense knowledge, knowledge of individuals, scientia, and faith. For Aquinas, scientia is the ability to understand an argument that is logically valid and knows the premises of the argument with certainty. He believes that reasoning, the act of drawing a logically valid conclusion from other propositions, is one of the sources of scientia.

To come to know the premises of a demonstration with certainty, Aquinas thinks that various powers and operations are necessary. He agrees with Aristotle that intellectual powers differ from the sensitive powers such as the five senses and imagination. However, Aquinas also believes that all human knowledge begins with sensation, and even our knowledge of God begins with what we know of the material world.

Aquinas argues that a comprehensive account of human cognition requires mentioning various interior senses as preambles to proper intellectual activity. Perfect animals, such as horses and oxen, must have a faculty that senses whether they are sensing and unifies the distinct sensations of the various sense faculties. This faculty is called common sense, and humans also possess this faculty.

In addition to common sense, Aquinas argues that we need phantasy or imagination to explain our experience of the cognitive life of animals, including humans. Perfect animals sometimes move themselves to a potential food source, and therefore, they need to imagine things they have never cognized by the exterior senses. The faculty of imagination is distinct from the exterior senses and the common sense, and humans are capable of imagining objects they have never cognized by the exterior senses.

To explain the behavior of perfect animals, we need to posit two additional powers: the estimative power, which perceives certain cognitions instinctively, and the memorative power, which retains cognitions produced by the estimative power. The presence of intellect in humans transforms the nature of these powers, with the estimative power being called the cogitative power and the memorative power called the reminiscitive power.

The cogitative power enables humans to make an individual thing, event, or phenomenon an object of thought, while the reminiscitive power helps us remember intellectual cognitions about individual objects.