Someone may say: "What is the point or use of making resolutions to live by truth if I am wrong about the nature of truth? I can easily imagine that I may be mistaken!"
Wrong question. The important thing to focus upon is the striving to live and striving in the right spirit. Then, when you are mistaken, you are in possession of an infallible force which will turn you away from error, will seize you, and will guide you back onto the right road.
To brood upon the theme of 'but I may be in error' is harmful, demotivating, nihilistic - it is a species of the sin of despair (a sin which will undermine any or all virtues, if given enough rope). It demonstrates lack of inner confidence in the power of the truth, and our capacity to know the truth - it represents a paucity of faith that God really loves us - since a loving God would not place us in a predicament with no way out of it.
While many or most people are prone to brood on the possibility of their own error, this is not - contra the spirit of the age - a virtue; it is not (for example) characteristic of 'a real scientist', it is not a sign of humility, it is not a sign of superiority of insight, or maturity, or sophistication,
The best that can be said about it, as with all sins, is that in the experience of overcoming it much may be learned - and one will have emerged a wiser and stronger man. But that does not excuse the sin of encouraging self-doubt in other people - as so often happens; any more than the fact that overcoming hatred leaves us wiser would make it right to encourage hatred in others.
Our path to truth is selflessly to yield ourselves to the guidance of the Holy Spirit - to striving in the right spirit. Nothing else will take us to the truth, and this will do so.
We must not indulge in self-doubt or we will easily become paralysed from fear of error. Men are not meant to be infallible unerring creatures - we are made to strive in the spirit of love, and we will surely err, and we will need to repent.
But so long as we maintain the right spirit, we cannot fail to return to our path. Self-doubt will not help prevent error, on the contrary it will place us in a frame of mind in which we will err and stray and not notice (as when a failure to act is by default smugly assumed to be the safest option) -- self-doubt will only prevent us living as we should: with faith and love and courage.