Is Sampajañña and Dhamma vicaya related?

Question

Does Sampajañña and Dhamma vicaya have an overlap. What is the relationship between the two? What is the differences? Is Sampajañña a result of dhamma vicaya? Do you need Sampajañña for dhamma vicaya?

Answer 1

In the stock passage defining Sama-Sati, right mindfulness, sampajanna is mentioned:

And what is right mindfulness? There is the case where a monk remains focused on the body in & of itself — ardent, alert, & mindful — putting aside greed & distress with reference to the world. He remains focused on feelings in & of themselves... the mind in & of itself... mental qualities in & of themselves — ardent, alert, & mindful — putting aside greed & distress with reference to the world. This is called right mindfulness.

Katamā cāvuso sammāsati: idhāvuso bhikkhu kāye kāyānupassī viharati ātāpī sampajāno satimā vineyya loke abhijjhādomanassaṃ. Vedanāsu vedanānupassī viharati ātāpī sampajāno satimā vineyya loke abhijjhā domanassaṃ. Citte cittānupassī viharati ātāpī sampajāno satimā vineyya loke abhijjhā domanassaṃ. Dhammesu dhammānupassī viharati ātāpī sampajāno satimā vineyya loke abhijjhā domanassaṃ. Ayaṃ vuccatāvuso sammāsati.

(http://www.accesstoinsight.org/tipitaka/mn/mn.141.than.html)

Thus a person who possesses right mindfulness also has Sampajanna. Dhamma Vicaya however, is not so closely related to mindfulness. Dhamma Vicaya is a result of mindfulness, not a part of it. Mindfulness is the first of the seven factors of enlightenment and Dhamma Vicaya is the second, and in the Anapanasati Sutta they are presented in sequence:

"[1] On whatever occasion the monk remains focused on the body in & of itself — ardent, alert, & mindful — putting aside greed & distress with reference to the world, on that occasion his mindfulness is steady & without lapse. When his mindfulness is steady & without lapse, then mindfulness as a factor for awakening becomes aroused. He develops it, and for him it goes to the culmination of its development.

"[2] Remaining mindful in this way, he examines, analyzes, & comes to a comprehension of that quality with discernment. When he remains mindful in this way, examining, analyzing, & coming to a comprehension of that quality with discernment, then analysis of qualities as a factor for awakening becomes aroused. He develops it, and for him it goes to the culmination of its development.

(http://www.accesstoinsight.org/tipitaka/mn/mn.118.than.html)