user-1: I have a straightforwards question: does meditation decrease attachments -- e.g. to alcohol or social media -- by increasing willpower, or by other mechanisms? I would think shamatha increases willpower in the long-term, but does it produce some other effects that decrease attachments?
Thank you.

user10100: When you concentrate out of alcohol, you are not attaching alcohol that time. The distance between you and alcohol will increase. This can be meditation, if your concentration concentrating samādhi object or vipassanā object continuously and  improvely. But, if not, it is  just a sīla, precept, if you just deny to drink an alcohol, because alcohol denying is just a precept in 5 precepts, so it is just meditation base, but it still not meditation.
Sīla-training stop whole physical attachment, not just alcohol. Sīla is base of meditation, but it is not meditation because mental attachment still able to arise. When any unwholesome mind, such as attaching mind arising, that time is not meditation, because the meditation is training  continuously and  improvely.
Samādhi-continuous-training stop whole present mental attachment.
Vipassanā-continuous-training extirpate whole future attachment.

user9861: Shamatha can be viewed as an off-shoot of the traditional Theravadin practice of mindfulness meditation. Its purpose is to establish “calm abiding” in which calm objectivity and common-sense understanding are extended to establish a meditative awareness of one’s state of mind, thoughts, and emotions. From a Theravadin point of view, the establishment of calm abiding is a good beginning but not an end in itself. Nonetheless, a calm and objective mind automatically corrects perceptions, feelings, beliefs, desires, and “attachments” that do not make sense to your common-sense mind. This is the mechanism that causes MBSR therapy to work. In this way, certain types of problematic sankhara (schemata) are revised. However, there are deeper and more problematic sankhara that cannot be corrected in this manner. The next level of mindfulness meditation consists of meditating on “the body in the body,” which is similar to the process of focusing developed by Eugene Gendlin. The more advanced levels of mindfulness meditation engage the Bodhicitta and require a lot more explanation. If you want to know more about these more advanced levels, you can read my book on how mindfulness meditation works.

user8157: Meditation can result in samatha (tranquility & joy) and vipassana (insight). 
On a very basic or crude level, meditation can provide an intimate insight into how addictions & habits disturb, trouble & enslave the mind, which can help the mind develop a distaste or dispassion towards these more coarse/gross addictions & habits. 
As for samatha, if well developed, it provides an alternate, more healthy & free source of pleasure. 
All minds require 'pleasure' however some sources of pleasure are more healthy than others. 

-1: <p>I have a straightforwards question: does meditation decrease attachments -- e.g. to alcohol or social media -- by increasing willpower, or by other mechanisms? I would think shamatha increases willpower in the long-term, but does it produce some other effects that decrease attachments?</p>

<p>Thank you.</p>
 10100: <p>When you concentrate out of alcohol, you are not attaching alcohol that time. The distance between you and alcohol will increase. This can be meditation, if your concentration concentrating samādhi object or vipassanā object <strong>continuously and  improvely</strong>. <strong>But, if not, it is  just a sīla, precept, if you just deny to drink an alcohol, because alcohol denying is just a precept in 5 precepts</strong>, so it is just meditation base, but it still not meditation.</p>

<p><strong>Sīla-training</strong> stop whole physical attachment, not just alcohol. Sīla is base of meditation, <strong>but it is not meditation because mental attachment still able to arise</strong>. When any unwholesome mind, such as attaching mind arising, that time is not meditation, because the meditation is training  <strong>continuously and  improvely</strong>.</p>

<p><strong>Samādhi-continuous-training</strong> stop whole present mental attachment.</p>

<p><strong>Vipassanā-continuous-training</strong> extirpate whole future attachment.</p>
 9861: <p>Shamatha can be viewed as an off-shoot of the traditional Theravadin practice of mindfulness meditation. Its purpose is to establish “calm abiding” in which calm objectivity and common-sense understanding are extended to establish a meditative awareness of one’s state of mind, thoughts, and emotions. From a Theravadin point of view, the establishment of calm abiding is a good beginning but not an end in itself. Nonetheless, a calm and objective mind automatically corrects perceptions, feelings, beliefs, desires, and “attachments” <em>that do not make sense</em> to your common-sense mind. This is the mechanism that causes MBSR therapy to work. In this way, certain types of problematic sankhara (schemata) are revised. However, there are deeper and more problematic sankhara that cannot be corrected in this manner. The next level of mindfulness meditation consists of meditating on “the body in the body,” which is similar to the process of focusing developed by Eugene Gendlin. The more advanced levels of mindfulness meditation engage the Bodhicitta and require a lot more explanation. If you want to know more about these more advanced levels, you can read my book on how mindfulness meditation works.</p>
 8157: <p>Meditation can result in samatha (tranquility &amp; joy) and vipassana (insight). </p>

<p>On a very basic or crude level, meditation can provide an intimate insight into how addictions &amp; habits disturb, trouble &amp; enslave the mind, which can help the mind develop a distaste or dispassion towards these more coarse/gross addictions &amp; habits. </p>

<p>As for samatha, if well developed, it provides an alternate, more healthy &amp; free source of pleasure. </p>

<p>All minds require 'pleasure' however some sources of pleasure are more healthy than others. </p>
