The topic of doxastic voluntarism is proving to be fascinating indeed. It is interestingly related to the topic of toleration about which I have something to say in On Toleration: With a Little Help from Kolakowski, in The Danger of Appeasing the Intolerant, and in Toleration and its Limits.
Let us begin today's meditation with a passage from John Locke's A Letter Concerning Toleration:
The articles of religion are some of them practical and some speculative. Now, though both sorts consist in the knowledge of truth, yet these terminate simply in the understanding, those influence will and manners. Speculative opinions, therefore, and articles of faith (as they are called) which are required only to be believed, cannot be imposed on any Church by the law of the land. For it is absurd that things should be enjoined by laws which are not in men's power to perform. And to believe this or that to be true does not depend on our will. (Treatise of Civil Government and A Letter Concerning Toleration, ed. Sherman, p. 204, emphasis added.)
The Lockean position seems to be as follows. What people believe is not under the direct control of their wills. This includes articles of religious faith. But the law cannot reasonably enjoin that which is not in the power of people to perform. 'Ought' implies 'can': if I am legally obliged to do X or refrain from Y, then it must be in my power to do X or refrain from Y. It follows that the holding, or the opposite, of speculative opinions cannot be reasonably imposed by the laws of the land. And because such opinions cannot be reasonably imposed, a diversity of such opinions must be tolerated by the temporal powers that be.
What I extract from the passage quoted, then, is a basis for toleration. In a nutshell: the falsity of doxastic voluntarism supports a policy of toleration. It is because we have no control over what we believe that the government has no right to command us to believe this or that.
But it seems that a doxastic voluntarist can just as easily argue for toleration. In his great essay, "The Will to Believe," William James asserts that "we have the right to believe at our own risk any hypothesis that is live enough to tempt our will." (The Will to Believe and Other Essays in Popular Philosophy, p. 29) James is opposing W. K. Clifford who famously remarked, "It is wrong always, everywhere, and for every one, to believe anything upon insufficient evidence." (Quoted in James, p. 8) Both Clifford and James are doxastic voluntarists: both hold that some beliefs are such that our believing them or disbelieving them is within our power. Thus both consider it proper to apply words like 'right' and 'wrong' and 'permissible' and 'impermissible' to believings. They both have an 'ethics of belief.' (Here is Clifford's article,"Ethics of Belief.")It is just that the content of their ethics of belief is wildly different.
Can we extract an argument for toleration from James? Perhaps from the following passage:
No one of us ought to issue vetoes to the other, nor should we bandy words of abuse. We ought, on the contrary, delicately and profoundly to respect one another's mental freedom: then only shall we bring about the intellectual republic; then only shall we have that spirit of inner tolerance without which all our outer tolerance is soulless, and which is empiricism's glory; then only shall we live and let live, in speculative as well as in practical things. (p. 30)
For example, we are free to believe the God hypothesis and free to reject it. That "mental freedom" is worthy of respect, and if we do respect it it, then we shall be tolerant of those who use their mental freedom differently than we do.
In sum, Locke's doxastic involuntarism and James' doxastic voluntarism are both compatible with a policy of toleration and both can be used to support it.