How to distinguish the different stages of insight in MN 24?

It's not that one comes before the other...

• why do you put a cast on a broken leg?
• because you want to have the bone fixated in place
• why do you want to have the bone fixated in place?
• because it is conducive to healing

This is analogical and maybe you can see that this line of inquiry does not describe a progressive eventuality such that first we cast the leg, then we fixate the bone before we start healing; and neither does the sutta passage.

Here too

Cetanākaraṇīyasutta—Bhikkhu Bodhi Aṅguttara Nikāya The Book of the Tens 10.2. Volition (1)–(2) “Bhikkhus, for a virtuous person, one whose behavior is virtuous, no volition need be exerted: ‘Let non-regret arise in me.’ It is natural that non-regret arises in a virtuous person, one whose behavior is virtuous.

(3) “For one without regret no volition need be exerted: ‘Let joy arise in me.’ It is natural that joy arises in one without regret.

(4) “For one who is joyful no volition need be exerted: ‘Let rapture arise in me.’ It is natural that rapture arises in one who is joyful. (5) “For one with a rapturous mind no volition need be exerted: ‘Let my body be tranquil.’ It is natural that the body of one with a rapturous mind is tranquil.

(6) “For one tranquil in body no volition need be exerted: ‘Let me feel pleasure.’ It is natural that one tranquil in body feels pleasure.

(7) “For one feeling pleasure no volition need be exerted: ‘Let my mind be concentrated.’ It is natural that the mind of one feeling pleasure is concentrated

.

(8) “For one who is concentrated no volition need be exerted: ‘Let me know and see things as they really are.’ It is natural that one who is concentrated knows and sees things as they really are.

(9) “For one who knows and sees things as they really are no volition need be exerted: ‘Let me be disenchanted and dispassionate.’ It is natural that one who knows and sees things as they really are is disenchanted and dispassionate.

(10) “For one who is disenchanted and dispassionate no volition need be exerted: ‘Let me realize the knowledge and vision of liberation.’ It is natural that one who is disenchanted and dispassionate realizes the knowledge and vision of liberation.

“Thus, bhikkhus, (9)–(10) the knowledge and vision of liberation is the purpose and benefit of disenchantment and dispassion; (8) disenchantment and dispassion are the purpose and benefit of the knowledge and vision of things as they really are; (7) the knowledge and vision of things as they really are is the purpose and benefit of concentration; (6) concentration is the purpose and benefit of pleasure; (5) pleasure is the purpose and benefit of tranquility; (4) tranquility is the purpose and benefit of rapture; (3) rapture is the purpose and benefit of joy; (2) joy is the purpose and benefit of non-regret; and (1) non-regret is the purpose and benefit of virtuous behavior.

“Thus, bhikkhus, one stage flows into the next stage, one stage fills up the next stage, for going from the near shore to the far shore.”

Ask me again if someone want the reference links.

Follow ven. Pa-Auk for going in detail.

1. sīlavisuddhi

Purification of personal behavior, verbal/physical. It's physical wholesome.

2. cittavisuddhi

Purification of mind moment's behavior, mental. It's mental wholesome.

3. diṭṭhivisuddhi

Purification of view about above body's elements and mental elements. The opposite view is mole-view, never analysis as elements completely perfectly.

4. kaṅkhāvitaraṇavisuddhi

Purification of view about the sequential process of body's elements and mental elements in the sequence of the dependent origination. The opposite view is the mole-view which become into the doubt about the sequential process of body's elements and mental elements (kaṅkhā).

So, if the practitioner has wrong idea about body's elements and mental elements because of no diṭṭhivisuddhi, the practitioner will mistakenly relate the relation of body's elements and mental elements. Then this step will go wrong.

Seeing the dependent origination should switching with recalling-pastlife-skill like the Buddha did at his enlightening night because only past life's karma and unwholesome of rebirth moment are easiest to see "do good get good, do bad get bad". This moment has only one karma effecting, which appear at the last mind-process of past life. The other moments are effected by wholesome and unwholesome, so the ordinary often mistakenly think "do good get bad, do bad get good".

After the Purification of view about the sequential process of body's elements and mental elements in the order of the dependent origination, then the practitioner can see mind's moment, trillion times per second, arising and vanishing. This is the beginning of seeing three characteristic of the realities, body moment and mind moment.

In this step, the practitioner can analysis between real wholesome mind moment, real unwholesome mind moment, trillion times per second. If not, use kalapasammasana method to practice this step until proficiently seeing the realities' arising and vanishing sequentially and relatively, trillion times per second.

5. maggāmaggañāṇadassanavisuddhi

Real wholesome mind moment is called Magga (path).

Real unwholesome mind moment is called Amagga (not path).

The object of above diṭṭhivisuddhi and kaṅkhāvitaraṇavisuddhi are three noble truth, except nibbana (cessation-noble-truth, because the practitioner can't see nibbana until enlightening moment arising).

Proficiency of understanding uncountable realities' arising and vanishing possibility of three noble truth is called ñāṇa (dukkhe ñāṇa, etc.)

Above ñāṇa is viewing uncountable realities' arising and vanishing possibility of three noble truth like a photographic memorial genius sciences seeing atomic structure in his head, so this ñāṇa is called dassana.

The above views, diṭṭhivisuddhi and kaṅkhāvitaraṇavisuddhi, are purified or not, are depending on how clear the practitioner seeing the noble truth. If the practitioner can't see the entire possible unwholesome arising on entire possible objects, Then this step will go wrong because the hidden unwholesome will arise between the insight meditation. And the unwholesome in this step is what the ordinaries never think they are unwholesome. That's one important of many reasons why we need to see the momentary arising and vanishing.

The practitioner can't see the momentary arising and vanishing without above proficient of kaṅkhāvitaraṇavisuddhi skill. The practitioner is going to be bias, dirty, confuse, complicated, misunderstood about analysis of real wholesome, real unwholesome, neither wholesome nor unwholesome. Then this step will go wrong.

That's why it's named maggāmaggañāṇadassanavisuddhi.

6. paṭipadāñāṇadassanavisuddhi

Proficiency of keeping the insight meditation going on, without any unwholesome in between, by understanding uncountable realities' arising and vanishing possibility of three noble truth is called ñāṇa (dukkhe ñāṇa, etc.)

Above ñāṇa is viewing of keeping the insight meditation going on, without any unwholesome in between, by understanding uncountable realities' arising and vanishing possibility of three noble truth like a photographic memorial genius sciences seeing atomic structure in his head, so this ñāṇa is called dassana.

If above maggāmaggañāṇadassanavisuddhi has only one unwholesome moment inbetween. Then this step will go wrong. Restart the meditation from sīlavisuddhi again.

7. ñāṇadassanavisuddhī

It's enlightening moment. All ñāṇa and dassana are purified at this only moment.

AN 10.13 says:

What are the five lower fetters? Identity view, doubt (vicikicchā), misapprehension of precepts and observances, sensual desire and ill will.

MN 24 uses the word "kaṅkhā" (translated in the question as "perplexity"), which, according to the dictionary, can mean either:

1. doubt; uncertainty; or

2. wish, desire, longing (per SN 7.18).

Regardless of the meaning of "kaṅkhā", SN 24.1 says a person that has given up "kaṅkhā" is called a 'stream-enterer', as follows:

When a noble disciple has given up doubt in these six cases, and has given up doubt in suffering, its origin, its cessation, and the practice that leads to its cessation,

Yato kho, bhikkhave, ariyasāvakassa imesu ca ṭhānesu kaṅkhā pahīnā hoti, dukkhepissa kaṅkhā pahīnā hoti, dukkhasamudayepissa kaṅkhā pahīnā hoti, dukkhanirodhepissa kaṅkhā pahīnā hoti, dukkhanirodhagāminiyā paṭipadāyapissa kaṅkhā pahīnā hoti—

they’re called a noble disciple who is a stream-enterer, not liable to be reborn in the underworld, bound for awakening.

ayaṁ vuccati, bhikkhave, ariyasāvako sotāpanno avinipātadhammo niyato sambodhiparāyano”ti

Therefore, based on SN 24.1, there appears no distinction between the fetter of vicikicchā & kaṅkhā.

Bhikkhu Bodhi offers footnote 288 in his Majjhima Nikaya explaining these 7 stages from the Visuddhimagga (which I personally do not agree with). Bhikkhu Bodhi does however appear to caste some skepticism upon MN 24 by saying this teaching is found nowhere else in the suttas except for in DN iii 28 (which adds two more stages).

Therefore, I can only offer my personal explanation/interpretation of MN 24, which is:

1. Purification of view (diṭṭhivisuddhi) is predominately intellectual, such as intellectually comprehending the teachings.

2. The above intellectual comprehension gives rise to faith & purifies the mind from doubt (kaṅkhāvitaraṇavisuddhatthā). Due to the absence of doubt, there is the faith or confidence to attempt to practise the path.

3. The above practise of the above learned teachings gives rise to knowledge & vision (ñāṇadassana) of the path, which is direct insight rather than intellectual acceptance. In other words, there is the knowledge & vision that whenever the mind is free from craving, attachment & self-view, the mind is free from suffering & tastes The Deathless.

4. The above purity of knowledge & vision of the path (maggāmaggañāṇadassanavisuddhatthā) gives rise to knowledge & vision of what the path is and what the path is not. Thus, even though this practitioner may develop samatha & bliss, they know samatha & bliss is not the path. Instead, what is the path is the continuous prevention & dropping of any craving, attachment & self-view and ultimately dispassion (viraga).

5. Therefore, by knowing with direct insight what is the true path and what are the potential pitfalls of a wrong path is , the practitioner purifies their knowledge & vision of the true path.