"What is ultimate truth?" is a question I often hear from people who are smart enough to know they don't already know the answer. Frankly, I don't think they even know what they are asking. We can't talk about ultimate truth until we've defined truth, at least enough to know what concept we are looking for the ultimate of.
Truth is that which is. Truth is reality expressed in words. Beyond that, all attempts to define it fall into circularity. Any terms used to define it are themselves dependent on it for their own definitions. Still, we all know what it means. To claim not to know what truth is denies one justification for thinking any statement or doing any willful action.
Waxing poetic about truth almost always results in error. Truth is not beauty. They are separate categories. Even if beauty ought to be truth, they are still separate categories because "is" and "ought" are separate categories. There is no connection between is and ought. Maybe there ought to be, but there isn't. Unanimous agreement by all the women who ever existed in space-time wouldn't make it otherwise.We can identify at least five types of truth:
a. truth seen without reference to anything else.
b. truth not dependent on, or limited by anything outside itself.
An example of an absolutely true statement:
e.g. The house is on the left side of the street.
The house may be on the left side of the street.
The house may be on either side of the street.
All that is absolutely true is also objectively true.
Examples of objective truth are the same as for absolute truth.
The house is on the wrong side of the street.
But unfortunately we can't identify ultimate truth without being dogmatic.
a. beyond which nothing exists
b. beyond which nothing is possible
We could arbitrarily say ultimate truth sums up all of absolute truth, or objective truth, or all five of the above types of truth. But that would defeat the purpose of calling it ultimate. Ultimate implies something non-arbitrary in its nature, and not arbitrarily defined, and not subject to contrary opinion.
Bottom line, folks: Ultimate truth is either a bogus category, or arbitrarily defined, or the Supreme Being.