How many times have you heard some bastard or bitch retort arrogantly and sarcastically retort to you:

That impolite and rude expression is a conversation inhibitor if there ever was one.

Clearly, the churlish person who makes such an asinine remark neither respects the person that churlish person makes the remark to, does not want further dialogue with the person attacked, and revealed a serious mental problem of the person who asked the nefarious question of "How do I know."

Let's analyze the question "How do I know?"

First off, it might seem that the person who retorts with such a confrontational remark actually does not know any logical or possible answer to what question resulted in a "How do I know" response - in other words, they really do not have a clue. They genuinely lack knowledge for an informative answer, and have no reasonable way to find out and acquire the info sought.

In that case, however, it would be sensibly polite to respond in a congenial way using different words with a different tone of voice. An answer such as "I do not know, and have no way to find out which I can think of" would be acceptable.

Stating a few Bible verses from the Old Testament book of Proverbs would be appropriate here:

Pr 11:17 A man who is kind benefits himself, but a cruel man hurts himself. Pr 12:14 From the fruit of his words a man is satisfied with good, and the work of a man's hand comes back to him.
Pr 14:6 A scoffer seeks wisdom in vain, but knowledge is easy for a man of understanding.
Pr 14:12 There is a way which seems right to a man, but its end is the way to death.
Pr 14:17 A man of quick temper acts foolishly, but a man of discretion is patient.
Pr 14:33 Wisdom abides in the mind of a man of understanding, but it is not known in the heart of fools.
Pr 15:21 Folly is a joy to him who has no sense, but a man of understanding walks aright.
Pr 15:23 To make an apt answer is a joy to a man, and a word in season, how good it is!
Pr 16:2 All the ways of a man are pure in his own eyes, but the LORD weighs the spirit.
Pr 16:21 The wise of heart is called a man of discernment, and pleasant speech increases persuasiveness.
Pr 17:12 Let a man meet a she-bear robbed of her cubs, rather than a fool in his folly.
Pr 17:13 If a man returns evil for good, evil will not depart from his house.
Pr 17:24 A man of understanding sets his face toward wisdom, but the eyes of a fool are on the ends of the earth.
Pr 17:27 He who restrains his words has knowledge, and he who has a cool spirit is a man of understanding.
Pr 18:4 The words of a man's mouth are deep waters; the fountain of wisdom is a gushing stream.
Pr 18:12 Before destruction a man's heart is haughty, but humility goes before honor.
Pr 19:11 Good sense makes a man slow to anger, and it is his glory to overlook an offense.
Pr 19:25 Strike a scoffer, and the simple will learn prudence; reprove a man of understanding, and he will gain knowledge.
Pr 20:3 It is an honor for a man to keep aloof from strife; but every fool will be quarreling.
Pr 20:5 The purpose in a man's mind is like deep water, but a man of understanding will draw it out.
Pr 21:2 Every way of a man is right in his own eyes, but the LORD weighs the heart.
Pr 21:16 A man who wanders from the way of understanding will rest in the assembly of the dead.
Pr 21:28 A false witness will perish, but the word of a man who hears will endure.
Pr 22:24 Make no friendship with a man given to anger, nor go with a wrathful man,
Pr 25:18 A man who bears false witness against his neighbor is like a war club, or a sword, or a sharp arrow.
Pr 25:28 A man without self-control is like a city broken into and left without walls.
Pr 26:12 Do you see a man who is wise in his own eyes? There is more hope for a fool than for him.
Pr 29:20 Do you see a man who is hasty in his words? There is more hope for a fool than for him.
Pr 29:22 A man of wrath stirs up strife, and a man given to anger causes much transgression.
Pr 29:23 A man's pride will bring him low, but he who is lowly in spirit will obtain honor.

Actually, the retort should - logically - be rephrased as:

At that point, the counter-response could begin to involve a lengthy and rather complex scientific dissertation on the physiology of how the brain, neurons therein, and so forth functions from a biological perspective pertaining to how (technically) a person is cognizant of something, has memory of it, etc.

Perhaps the retort of "How do I know" is based upon intention to keep a secret - for whatever questionable cause - and thus the dishonest and lying response of: "How do I know?"

The retort could reveal either impatience, mental laziness, or a combination of both. Or maybe the person making the hostile retort has an inferiority complex, and is afraid (i.e. has a phobia) of being wrong in stating possible scenarios so as to not be criticized for possibly being wrong. They therefore emphatically, dogmatically, boastfully and belligerantly state their pathetic and laughable ignorance.

Whatever the case, the wisdom of Solomon should always guide the utterances out of that big hole under a person's nose. As Saint James keenly observed: "The tongue is a fire, an unruly member, staining the whole body, set on fire by hell." (James 3:6)

"The testimony of Jesus is the spirit of prophecy" as John stated in the book of Revelation. Saint Paul wants us all to prophesy (according to First Corinthians chapter 14) and by that he means to honestly and truthfully disclose the thoughts and intentions of the heart of someone else. For those who are authentically led by the Holy Spirit of Jesus Christ, is sometimes is possible to "know what a person is thinking." As Jesus reminds us: "By their fruits you will know them." Indeed.