In a current thread frequent objector EG comments — and yes, I am catching up:
KF and others talk about “objective” as being something that is unchangeable. For example, homosexuality is objectively wrong. Always was, always will be. This doesn’t change with the times. But you argue that my preference of ice cream flavor is also objectively true. If my preference for ice cream is objective, and changeable, then other objective things, like moral values, are also changeable.
For one, what I have said about objectivity (or rather, what Wikipedia has been forced to admit against obvious ideological inclination) is:
Objectivity is a philosophical concept of being true independently from individual subjectivity caused by perception, emotions, or imagination. A proposition is considered to have objective truth when its truth conditions are met without bias caused by a sentient subject. [Wikipedia, acc. 2019:11:17]
In the case of a taste for an ice cream flavour F1, it is true at a given time t1 that a particular subject S may wish by way of preference for F1, and that at subsequent time t2, may switch to F2. But it remains eternally true that at t1, S prefers F1. Such preference at that time being reportable and observable from choices often made. However, flavour preference is not a core defining characteristic or binding law of morally governed nature for S. (The attempted analogy regarding law of sexual morality, or first duties of right reason, etc thus fails immediately.)
The change from F1 to F2 does not fundamentally alter S’s core characteristics or nature, nor [under any reasonable circumstances] would such a change of habits potentially destabilise or undermine human thriving in a Categorical Imperative sense, even were it universalised.
Now, I have in fact made some personal observations on objectivity, e.g.:
>>. . . to be objective we need
 a framework that warrants claims as credibly true and so reliable, as well as
 a tolerably effective means of detecting and improving on our errors.
None of that requires that the
domains so contemplated only comprise concrete, material entities. Or
even that we have arrived at comprehensively absolute truth as a body,
i.e. while we know some self evident and some other necessary plumb line
truths, there is no need to assume or pretend that our system as a
whole or for the most part is free of errors. Hence, the concept: improve on.
Here, we may next contrast degrees of truth:
[i] subjective truth as perceived to be so by some individual or group (which is not at all to be dismissively equated with delusion or imagination or whim), with
[ii] absolute truth which is true, the whole material truth and nothing but that truth (say, as known to God [who knows perfectly and completely]), and again with
[iii] objective truth, i.e. what we [who are finite and fallible but rational . . . ] may have good warrant and even a duty to hold as credibly and reliably true independent of our particular subjectivity (given the adequacy of the warrants) but which is open in principle to sound correction.
This then brings us to the crucial importance of known, inescapable first duties of right reason, to truth, to sound reasoning, to prudence (thus, to warrant), to sound conscience, to fairness and justice etc.
Where, warrant is the process and result of so fulfilling cognitive duties of care that the said result is credibly true and reliable, worthy of being acted on — even, in those cases . . . the vast majority, in practice . . . that we cannot deliver utterly incorrigible certainty. Warrant, is not to be equated with mere persuasion, it is asking if the reason for a belief or opinion is sound or at least reliable (not, that we merely have a personal or collective right to it or that we may agree to accept it). Let us dip a little more deeply, to clarify warrant given the widespread tendencies of subjectivism and/or relativism:
DETAIL POINT: In effect, subjects S1 to Sn may agree to or hold a proposition p, but that is so far only opinion or belief that may be shared. They may also — a further step — be within epistemic rights to hold that p, but under certain circumstances . . . explored by Gettier and others . . . that personal justification and actual truth might be “accidentally” or otherwise “unreliably” connected due to circumstances faced by S1 to Sn that fail to justify independent of personalities and their particular situation. (For simple example, our visual, auditory and other senses can lose proper functionality or be in situations that create illusions, etc.) For p to be warranted (and notice the shift from subjects to the propositions), the connexion between epistemic rights and credible truth and reliability must not be accidental or personality/group-dependent. Warrant, in short, must be objective.
This is the context in which we therefore embark on logic, i.e.
LOGIC, DEF’N: logic is the core philosophical discipline that systematically studies sound argument thus first principles of truth, reason and reliable warrant, exposing along the way the many pitfalls of error and ways of deceit — that is, fallacies.
DETAIL/ENRICHMENT POINT: For a survey on what Logic is, kindly see an in-a-nutshell focussed on the classic first three laws of thought — to be discussed further below — here. Enc. Brit online here, compare Catholic Enc here for a more traditional/aristotelian review, and a Bible-based 53 pp, pdf discussion for use in home schools here. IEP provides a list of 200+ “major” fallacies here.>>
The problem we obviously have, is that issues connected to core characteristics of our nature as rational, responsible, significantly free — and therefore, of that nature, morally governed — creatures, is being confused with matters of little or no import. Ultimately, that is because under evolutionary materialistic scientism we don’t have natures; we are just accidental collocations of certain organic molecules that somehow manage to have become self-replicating and found ways to survive from one generation to the next. Fellow traveller ideologies come along for the ride.
Such of course fatally undermines both the credibility of the mind and moral government. The invited nihilism is manifestly ruinous. END