Thomas ReidThomas Reid was a founder of the Scottish School of Common Sense Philosophy, and an influential contemporary of David Hume. He succeeded Hume at the College of Glasgow and was Hume's first commentator. Reid is often cited as originating the idea of agent-causal libertarianism, that a moral agent has "power over the determinations of his own will." More particularly, that the determination of his will not "be the necessary consequence of something involuntary in the state of his mind, or of some thing in his external circumstances." What might Reid have thought then of something random and thus involuntary in his mind or in the external circumstances, but something that is only an additional option for his subsequent evaluation and determination, something that is in no way necessitates his will? A random event that is not the direct cause of action. The likely answer is that, like most philosophers with an antipathy to chance, Reid would have not even considered it. Or if he did, he would consider it atheistic. For Reid, the "power of the agent to do well or ill" is a "gift of God." Reid's fundamental idea can be traced back to mind-body dualists such as Descartes, scholastics such as William of Ockham, and Greek thinkers such as Aristotle, since the basic idea is that the mind can initiate causes and originate actions independently of any physical materialist causes. On another level, human freedom is the "common sense" view of all but the most philosophical thinkers of all time. Even Isaac Newton, the icon of physical determinism, was convinced God had given man the free power to move physical objects at will. In modern times many agent-causal libertarians have followed Reid, including Roderick Chisholm, Richard Taylor, Keith Lehrer, Timothy O'Connor, and Randolph Clarke.
On the Liberty of Moral AgentsOn the Active Powers, Essay IV, Chapter I, in The Works of Thomas Reid, William Hamilton, ed., p.599) THE NOTIONS OF MORAL LIBERTY AND NECESSITY STATED BY the Liberty of a Moral Agent, I understand, a power over the determinations of his own Will.*
If, in any action, he had power to will what he did, or not to will it, in that action he is free. But if, in every voluntary action, the determination of his will be the necessary consequence of something involuntary in the state of his mind, or of some thing in his external circumstances, he is not free; he has not what I call the Liberty of a Moral Agent, but is subject to Necessity. This Liberty supposes the agent to have Understanding and Will; for the determinations of the will are the sole object about which this power is employed; and there can be no will without such a degree of understanding, at least, as gives the conception of that which we will. The liberty of a moral agent implies, not only a conception of what he wills, but some degree of practical judgment or reason.  For, if he has not the judgment to discern one determination to be preferable to another, either in itself or for some purpose which he intends, what can be the use of a power to determine? His determinations must be made perfectly in the dark, without reason, motive, or end. They can neither be right nor wrong, wise nor foolish. Whatever the consequences may be, they cannot be imputed to the agent, who had not the capacity of foreseeing them, or of perceiving any reason for acting otherwise than he did. We may, perhaps, be able to conceive a being endowed with power over the determinations of his will, without any light in his mind to direct that power to some end. But such power would be given in vain. No exercise of it could be either blamed or approved. As nature gives no power in vain, I see no ground to ascribe a power over the determinations of the will to any being who has no judgment to apply it to the direction of his conduct, no discernment of what he ought or ought not to do. For that reason, in this Essay, I speak only of the Liberty of Moral Agents, who are capable of acting well or ill, wisely or foolishly, and this, for distinction's sake, I shall call Moral Liberty. What kind or what degree of liberty belongs to brute animals, or to our own species, before any use of reason, I do not know. We acknowledge that they have not the power of self-government. Such of their actions as may be called voluntary seem to be invariably determined by the passion, or appetite, or affection, or habit, which is strongest at the time. This seems to be the law of their constitution, to which they yield, as the inanimate creation does, without any conception of the law, or any intention of obedience.  But of civil or moral government, which are addressed to the rational powers, and require a conception of the law and an intentional obedience, they are, in the judgment of all mankind, incapable. Nor do I see what end could be served by giving them a power over the determinations of their own will, unless to make them intractable by discipline, which we see they are not. The effect of moral liberty is, That it is in the power of the agent to do well or ill. This power, like every other gift of God, may be abused. The right use of this gift of God is to do well and wisely, as far as his best judgment can direct him, and thereby merit esteem and approbation. The abuse of it is to act contrary to what he knows or suspects to be his duty and his wisdom, and thereby justly merit disapprobation and blame. By Necessity, I understand the want of that moral liberty which I have above defined. If there can be a better and a worse in actions on the system of Necessity, let us suppose a man necessarily determined in all cases to will and to do what is best to be done, he would surely be innocent and inculpable. But, as far as I am able to judge, he would not be entitled to the esteem and moral approbation of those who knew and believed this necessity. What was, by an ancient author, said of Cato, might, indeed, be said of him: He was good because he could not be otherwise. But this saying, if understood literally and strictly, is not the praise of Cato, but of his constitution, which was no more the work of Cato than his existence. On the other hand, if a man be necessarily determined to do ill, this case seems to me to move pity, but not disapprobation. He was ill, because he could not be otherwise. Who can blame him? Necessity has no law.  If he knows that he acted under this necessity, has he not just ground to exculpate himself? The blame, if there be any, is not in him, but in his constitution. If he be charged by his Maker with doing wrong, May he not expostulate with him, and say — Why hast thou made me thus? I may be sacrificed at thy pleasure, for the common good, like a man that has the plague, but not for ill desert; for thou knowest that what I am charged with is thy work, and not mine. Such are my notions of moral liberty and necessity, and of the consequences inseparably connected with both the one and the other. This moral liberty a man may have, though it do not extend to all his actions, or even to all his voluntary actions. He does many things by instinct, many things by the force of habit, without any thought at all, and consequently without will. In the first part of life, he has not the power of self-government anymore than the brutes. That power over the determinations of his own will, which belongs to him in ripe years, is limited, as all his powers are ; and it is, perhaps, beyond the reach of his understanding to define its limits with precision. We can only say, in general, that it extends to every action for which he is accountable. This power is given by his Maker, and at his pleasure whose gift it is it may be enlarged or diminished, continued or withdrawn. No power in the creature can be independent of the Creator. His hook is in its nose; he can give it line as far as he sees fit, and, when he pleases, can restrain it, or turn it whithersoever he will. Let this be always understood when we ascribe liberty to man, or to any created being. Supposing it therefore to be true, That man is a free agent, it may be true, at the same time, that his liberty may be impaired or lost, by disorder of body or mind, as in melancholy, or in madness; it may be impaired or lost by vicious habits; it may, in particular cases, be restrained by divine interposition.  We call man a free agent in the same way as we call him a reasonable agent. In many things he is not guided by reason, but by principles similar to those of the brutes. His reason is weak at best. It is liable to be impaired or lost, by his own fault, or by other means. In like manner, he may be a free agent, though his freedom of action may have many similar limitations. The liberty I have described has been represented by some philosophers as inconceivable, and as involving an absurdity. "Liberty, they say, consists only in a power to act as we will; and it is impossible to conceive in any being a greater liberty than this. Hence it follows, that liberty does not extend to the determinations of the will, but only to the actions consequent to its determination, and depending upon the will. To say that we have power to will such an action, is to say, that we may will it, if we will. This supposes the will to be determined by a prior will; and, for the same reason, that will must be determined by a will prior to it, and so on in an infinite series of wills, which is absurd. To act freely, therefore, can mean nothing more than to act voluntarily; and this is all the liberty that can be conceived in man, or in any being." This reasoning — first, I think, advanced by Hobbes* — has been very generally adopted by the defenders of necessity. It is grounded upon a definition of liberty totally different from that which I have given, and therefore does not apply to moral liberty, as above defined.**
But it is said that this is the only liberty that is possible, that is conceivable, that does not involve an absurdity.  It is strange, indeed, if the word Liberty has no meaning but this one. I shall mention three, all very common. The objection applies to one of them, but to neither of the other two. Liberty is sometimes opposed to external force or confinement of the body. Sometimes it is opposed to obligation by law, or by lawful authority. Sometimes it is opposed to necessity. 1. It is opposed to confinement of the body by superior force. So we say a prisoner is set at liberty when his fetters are knocked off, and he is discharged from confinement. This is the liberty defined in the objection; and I grant that this liberty extends not to the will, neither does the confinement, because the will cannot be confined by external force.•
2. Liberty is opposed to obligation by law, or lawful authority. This liberty is a right to act one way or another, in things which the law has neither commanded nor forbidden; and this liberty is meant when we speak of a man's natural liberty, his civil liberty, his Christian liberty. It is evident that this liberty, as well as the obligation opposed to it, extends to the will: For it is the will to obey that makes obedience ; the will to transgress that makes a transgression of the law. Without will there can be neither obedience nor transgression. Law supposes a power to obey or to transgress; it does not take away this power, but proposes the motives of duty and of interest, leaving the power to yield to them, or to take the consequence of transgression. *
3. Liberty is opposed to Necessity, and in this sense it extends to the determinations of the will only, and not to what is consequent to the will.* 
In every voluntary action, the determination of the will is the first part of the action, upon which alone the moral estimation of it depends. It has been made a question among philosophers, Whether, in every instance, this determination be the necessary consequence of the constitution of the person, and the circumstances in which he is placed; or whether he had not power, in many cases, to determine this way or that? This has, by some, been called the philosophical notion of liberty and necessity; but it is by no means peculiar to philosophers. The lowest of the vulgar have, in all ages, been prone to have recourse to this necessity, to exculpate themselves or their friends in what they do wrong, though, in the general tenor of their conduct, they act upon the contrary principle.*
Whether this notion of moral liberty be conceivable or not, every man must judge for himself. To me there appears no difficulty in conceiving it. *
I consider the determination of the will as an effect. This effect must have a cause which had power to produce it; and the cause must be either the person himself, whose will it is, or some other being. The first is as easily conceived as the last. If the person was the cause of that determination of his own will, he was free in that action,* and it is justly imputed to him, whether it be good or bad. But, if another being was the cause of this determination, either by producing it immediately, or by means and instrument under his direction, then the determination is the act and deed of that being, and is solely imputable to him.
But it is said — " That nothing is in our power but what depends upon the will, an, therefore, the will itself cannot be in our power." I answer — That this is a fallacy arising from taking a common saying in a sense which it never was intended to convey, and in a sense contrary to what it necessarily implies.  In common life, when men speak of what is, or is not, in a man's power, they attempt only to the external and visible effects which only can be perceived, and which only can affect them. Of these, it is true that nothing is in a man's power but what depends upon his will, and this is all the is meant by this common saying. But this is so far from excluding his will from being in his power, that it necessarily implies it. For to say that what depend upon the will is in a man's power, but the will is not in his power, is to say that the end is in his power, but the means necessary to that end are not in his power, which is contradiction. In many propositions which we express universally, there is an exception necessarily implied, and, therefore, always understood. Thus, when we say that all things depend upon God, God himself is necessarily excepted. In like manner, when we say that all that is in our power depends upon the will, the will itself is necessarily excepted: for, if the will be not, nothing else can be in our power. Every effect must be in the power of its cause. The determination of the will is an effect, and, therefore must be in the power of its cause, whether that cause be the agent himself, or some other being. From what has been said in this chapter, I hope the notion of moral liberty will be distinctly understood, and that it appears that this notion is neither inconceivable, nor involves any absurdity or contradiction.