1. If p then q; p is true; therefore q is true.
2. If p then q; q is untrue; therefore p is false.
3. Not (both p & q); p is true; therefore q is false.
4. Either p or q is true; p is true; therefore q is false.
5. Either p or q is true; q is false; therefore p is true.
That this is different from the limited form of symbolic logic in use merely demonstrates to us that its "truth value" does not correspond to reality. Reasoning requires the refinement and effort to make ourselves into the best people we can be.
To be sure, our ethics is a system which locates goodness solely in the proper functioning of reason. Hence we do resemble Kant in judging the moral worth of an action solely in terms of the agent's reasons and intentions, and not in terms of its outcome. But Kant arrives at this position by very different steps from ourselves, and even the points in which we seem to resemble one another need careful elucidation. Unlike Kant, we think that reason cannot function properly unless it seeks to produce results which are "in accordance with nature", i.e. agreeable to one's own normative condition and that of others. The legislative principles on which we act are grounded in empirical data -- e.g. the naturalness of health, family affection, and social cohesion to human beings. We think that well-fuctioning rational beings should do everything in their power to promote these states of affairs, and that happiness consists precisely in such efforts and in the mental states that accompany them.
Our critcs are reluctant to take us seriously when we make this claim. This is because we deny that happiness requires us to possess or succeed in implementing any of the things we rationally seek to promote. But there is no in compatibility: look at the way things are. Rason constrains you to agree that we should seek to promote all things that accord with our natures: our health, our family relationships, our lives as citizens, &c. Equally, reason constrains you to admit that such objectives may sometimes conflict, requiring you to prefer one to another, and that the final outcome of all such efforts is not something for which you are solely answerable or which can have any bearing on the goodness of trying to promote such things. Consequently we conclude that thoroughly rational will be content and happy entirely in the proper exercise of their rational faculties.
Our ethics make sense only on thbe assumption that we value happiness above anything else. However, in order to find our postion palatable, it is essential to recognize that we defend positions that some object to: first, determinism; second, its equivalent, divine providence; third, the availability of happiness to every normal person; fourth, the perfectability of reason. If you reflect sufficiently on those positions and accept them, you will find that we offer an account of happiness that is fully coherent, and neither impoverished or disingenuous. If you cannot recognize those positions, we are neither your predecessors nor successors.