Samatha Only Wisdom

Can we gain wisdom(panna or prajna) with only one pointed concentration on a concept?

Concept??? One-pointedness of mind (citta ekaggata) is not related to a concept or concepts.

I've heard it said that it takes mindfulness on "what actually is" instead of a concept that doesn't exist.

Mindfulness does not mean "to see" or "to observe". "Mindfulness" means "to remember" or "keep in mind".

Samatha, at least temporarily, lessons the defilements

Yes.

so why wouldn't concentration meditation be able to show one panna?

Yes. It can. The wisdom (panna) that can arise directly from concentration & samatha is that it is peaceful to be without defilements; that defilements are unwholesome & suffering.

Can one gain panna without seeing the three characteristics?

Yes. But this panna (wisdom) will not be complete & will not 'uproot' the defilements.

Can one see the three characteristics with Samatha by itself?

No. However, one can experience 'selflessness' (a mind without self) but this is not the same as seeing the not-self (anatta) characteristic of each of the five aggregates.

Can we reach Nirvana with just Samatha?

No. But we can have a 'taste' of Nirvana, i.e., develop the conviction that complete Nirvana exists.

No, Samatha alone can't reach Nirvana; even Vipassana can't; neither Nirvana necessarily produced by any Dhyana. Although recorded in the Vinaya Uppalavanna was entering the 9th Dhyana when staying in the Dark Forest where 500 robbers happened also tracked there, she was not entering Nirvana, she arose from the Dhyana the next morning. The 9th Dhyana called the "extinguishing" meditation (滅盡定) was the Buddha's unique discovery, he had learnt the 8 Dhyanas from his teachers that were known and practiced by the heretics at his time.

I read from my sources Samatha (止) and Vipassana (觀) are always going together in Dhyana, they can't happen on its own, like a hand with the palm and back. Samatha is taking a passive approach, when thoughts arise, abandon that thoughts, closely observes any thought arose abandoned immediately - present of mind (not absent of mind, think of what is absent-minded, the opposite); Vipassana is taking the active approach, focus and work on the chosen meditation object, alert and patiently waiting for revelation.

I've not heard that the three characteristics are to be considered as the rule to be obeyed in all meditation practices. They are the truth Buddha obtained in his own Prajna quest, he just told you that are the correct answers. But to learn, you have to work out the same answer. As a student working out the equation by doing computing, using calculator to output an answer or copying from your classmate doesn't mean you know the answer, you must be able to do the calculation on your own, then you obtain the answer - the Dharma, else they are just terms, vocabularies. So, you may choose one of the characteristics as your object to work your Vipassana on it. Personally I found that a visual object is easier to work Vipassana on, rather than concept. Maybe I'm just a beginner not knowing the sophistication of meditation yet. Samatha can't derive Prajna, it is just a background building for Vipassana to set on working, Prajna obtained by Vipassana. Even the Anapana meditation included Samatha and Vipassana, Samatha as setting mind to the breathe, the breath is also the object in Vipassana.

Can one gain panna without seeing the three characteristics?

No, as far as Buddhist teaching concern. Here Panna means the wisdom of complete liberation. The wisdom you get from Samath is only a partial liberation.

Samatha just results in the suppression of 5 Hindrances using a conceptual object as the focus. Vipassana Bhavana is the focus on the ultimate realities free from concepts, which are rupa, citta, cetasika and nirvana and the universal characteristics of them to free your mind from the corruptions of insight so you can understand causality. E.g. contemplation of the body is to understand the nature of rupa and also eliminate the corruption of insight of beauty. Understanding causality helps understand the arising of defilements. You can choose the object of concentration be tied with ultimate realities which a proxy is the 4 Foundations of Mindfulness (body - rupa, rest relates to citta & cetasika). More on this see: Samatha and Vipassanā: Concentration and insight meditation by Ashin Dr. Nandamālābhivaṃsa

For wisdom you need to abandon ignorance of the 4 Noble Truths and Dependent Origination, i.e., understand causality. For this would should 1st you should free your mind of corruption of insight by knowing the 3 marks of existence, which is, wise attention or seeing thing as they are. This with equanimity help you understand causality at the experiential level.

Samatha can help by removing the hindrances which mean you have more clarity but this alone will not help.

There is not even a single reference in the Tipitaka, where the Buddha has said that “samatha bhavana” alone can lead to Panna/wisdom. But when one comprehends Dhamma, one’s mind get calm and through that samatha state, and one can get to magga phala.

After attaining the Sotapanna / Stream Entrant stage, one can get to Ariya jhanas by focusing on that “state of cooling down”. One really needs insight meditation (vipassana) to attain higher magga phala.

The suppression of all five hindrances is what is commonly called “samatha“. One does not need to do a special “samatha bhavana” (like the breath meditation) to calm the mind. If one pays enough attention and gets absorbed in the subject matter while listening to or reading Dhamma, one could suppress all five hindrances / come to “samatha“.

In hearing the true message of the Buddha of anicca, dukkha, anatta, one can experience “Niramisa sukha“ as one starts seeing a glimpse of the “true nature of this world”.

In “Samatha bhavana” one forces the mind to one thought object, and the five hindrances are kept at bay. When developing this, one feels the serenity of a mind unpolluted by the hindrances. This is called samatha meditation.

There a four ways to come to ‘Panna’. if you read AN 4.170 Yuganaddha Sutta, there are four types. Calmness (samatha) & insight (vipassana) are developed simultaneously is the third of the four types, called ‘Yuganaddha’. The first of the four is 'samatha purvangama vipassana' where one develops tranquility preceded by insight. In ' vipassana purvangama samatha ' one develops insight first and it is preceded by tranquility. How it gets developed depends on the personality type.

Nope. No matter how deep your samatha practice, the mind still has to be brought back to the world of form. I think we've all heard the quote from Einstein - "We can't solve problems by using the same kind of thinking we used when we created them." Buddhism more or less follows the same approach. You change your place of thinking/perceiving by quieting the mind and suppressing the hindrances. You are still, however, charged with the task of solving the problem at hand. For that, you need an object of mindfulness. That can be a koan, one of the many mindfulness practice available in the elder tradition, hearing a sutra, or even hearing the sound of a rock hitting bamboo.