What exactly is svabhava? What exactly is svabhāva in Nagarjuna's Madhyamaka?

It is translated as inherent nature or inherent existence or inherent substance. But what does that really mean?

Does it carry the same meaning as being unconditioned? If yes, then Nirvana and the Buddha's Dharma, being unconditioned, must have svabhāva. But they don't, according to Madhyamaka.

Why does a chair or a photon or empty space or concepts or the Dharma (teachings) or Nirvana have no svabhāva?

From the Wikipedia article on Madhyamaka, it sounds like something that is unconditioned has svabhāva. But that's not right according to Madhyamaka.


  Nagarjuna's critique of the notion of own-nature
  argues that anything which arises according to conditions, as all
  phenomena do, can have no inherent nature, for what is depends on what
  conditions it. Moreover, if there is nothing with own-nature, there
  can be nothing with 'other-nature' (para-bhava), i.e. something which
  is dependent for its existence and nature on something else which has
  own-nature. Furthermore, if there is neither own-nature nor
  other-nature, there cannot be anything with a true, substantial
  existent nature (bhava). If there is no true existent, then there can
  be no non-existent (abhava).
Svabhāva stands for inherent existence.

From an early Madhyamika viewpoint, there are two types of dependent-arising:


Causal dependence
Dependence on parts


While impermanent phenomena depend on both causes and parts, permanent phenomena do not depend on causes and conditions but they do depend on parts. For instance, a chair is impermanent and depends on causes (if it is made of wood, wood is a substantial cause, etc) and depends on its parts (the legs, etc). Permanent phenomena such as space, emptiness, cessations, etc. depend on parts. For instance, emptiness is emptiness of something on which it depends (not causally, but in terms of part). Therefore, even emptiness, a permanent phenomena, is empty of inherent existence because it is a dependent-arising.

From a Madhyamika-Prasangika viewpoint, there are two types of dependent-arising. The third level is the most subtle:


Dependence on name.


We say that the meaning of something being empty of svabhāva is that, if you look for it with a mind analyzing the ultimate, you will not find it. Now, if you ask yourself "is the chair its legs... is it the material it's made of... etc" you will find that the chair is merely labeled upon these without being any of these. We say that it is "merely labeled".


This presentation is incomplete and cartoonish because there are various Madhyamika [sub]schools, some for which inherent existence and true existence are synonymous, some not.