Thomas agrees with Aristotle regarding in what faculty happiness is found. Aristotle limits the state of happiness to those beings which have the capacity for rational thought. He says, “Happiness is an activity of the [rational] soul” (Aristotle, Nicomachean Ethics, 1100a15). Thomas echoes and expands on this when he says “happiness is the proper good of the intellectual nature” (Thomas Aquinas: Selected Writings, Penguin Books., London 1998, p 268).
Arriving at the link between ‘happiness,’ ‘the proper good,’ and the ‘intellectual nature’ occurs after discounting the various misconceptions regarding what happiness/the proper good are, namely physical pleasure, honour, wealth and any other pursuits which are not ‘self-sufficient’ but rather transitory and contingent. Also, finding happiness in the intellect involves recognizing that the intellect is our highest faculty. As sight is are our highest sensory faculty by which we are able most accurately to perceive the world around us, so our intellects are our highest faculty, enabling us to understand the world around us. Happiness and the proper good are bound up with our telos. It is the intellectual nature which is the specific difference between humans and all other created compound beings (the imago dei), and thus our happiness is to be found in relation to our intellectual nature. Thus, true happiness for us is to be found in intellectual activities directed towards God. “God is the ultimate end of the intellectual substance and that operation whereby a man first attains God is said to be substantially his happiness or felicity” (Aquinas, Selected Writings, p. 270). This ‘attaining’ is some kind of intellectual sight – the Beatific Vision.
The essential problem with understanding happiness as being found within the act of the will is that it places happiness within a lesser faculty than the intellect. Thus we are at risk of being confused about or even degrading our human telos. The priority of the will may degrade our telos from the simplicity of the intellectual sight or ‘attainment’ of God to that faculty which serves the multifarious pursuits of human creaturely existence. Also, the will, while being an important faculty, is not what makes us specifically different from other irrational creatures. All animals have appetites (i.e., for physical pleasure, food, and other things beneficial for whatever a species requires in order to attain its telos). As we are animals (intelligent animals), our appetites serve similar contingent ends as other animals. Like the will, the various contingent goods are not in and of themselves bad necessarily unless we confuse them with our highest good (like confusing the preeminence of the intellectual faculty with the faculty of our wills, we may also confuse the preeminence of the pursuit of God with the pursuit of ‘this-worldly’ things). Aquinas says that ‘the will’ is essentially our appetite ‘in proportion’ to our intellectual natures (Aquinas, Selected Writings p 268). The will never wills for its own sake, but is only ever moved by an appetite for some external thing it wants or needs. As we are intelligent animals, our wills need to be ordered towards that higher specific difference and ability accordingly. This being the case, as the will does not will it’s own activity, it cannot itself be the ‘ultimate end’ of the person. It must ultimately serve our human intellectual capacity, and our intellectual true happiness is not to be found in various appetites and desires, but in attaining to the source of our intellects, and that which most satisfies our intellects, namely God.
All of this matters because there are far-reaching consequences to prioritizing the will over the intellect. As far as I understand, this is a matter of contention within Christian theological and philosophical thought (two saints, Bonaventure and Aquinas are on different sides of this issue). I hold, in so far as I understand it, the intellectualist position of Aquinas over Bonaventure’s voluntarist position (and certainly Duns Scotus’ voluntarist position). To think of the issue analogously, as the Spirit proceeds from the Father (and the Son) and serves their purposes, so the will serves the intellect.