By Rabbi Dovid Markel
In discussing the the “tzimtzum” that was necessary in creating the world, the Arizal uses the term “when it arose in his simple will (רצונו הפשוט).” Reb Ahron of Strashela focuses on the logical incongruity of this statement – and explains its intention.
Understanding it adds appreciation in the difference between chassidic philosophy, and Aristotle, Plotinus, Stoics, Spinoza et al. In all there philosophies the world is a natural extension of G-d and is necessary as opposed to voluntary.
However, an essential point of faith in chassidic thought ( based partly on the Guide to the Perplexed 2:12-17) is that the world was created ex nihilo by G-d’s will , and G-d – being perfect – is not forced to do anything.
That being the case, G-d must have willed the creation of the world. This leads though to an even greater problem though. For, if G-d is perfect, then he must be must not be subject to change!
Reb Ahron enumerates various problems with will in G-d:
1) All will is indicative of change from before He willed to after.
2) All will is to something outside of one’s self – as there is nothing outside of G-d, how can he desire?
3) All will has something that forces the will – for example hunger forces a desire for food – It is impossible that there was a cause that caused G-d to will.
4) Desire is indicative that there was something lacking – and is expressive of “parts” as G-d is perfect and “akhdut peshuta” a simple unity, it is impossible for him to want.
It is this point that the Arizal wishes to express – according to Reb Ahron – in his use of the language, “simplistic desire,” (רצון הפשוט). It brings out that essentially the concept of “will” is merely allegorical to negate that it was forced – for this too is impossible.
However, what exactly was His “will” and how is impossible for a mortal to understand, for as the verse (Isaiah 55:8) states: “”For My thoughts are not your thoughts, neither are your ways My ways.”
This though – although clearly not understood – presents an axiomatic difference between various modes of philosophy and the Chabad chassidic concept of G-d.
 Etz Chaim, 1:2
 Sharei HaYichud VeHaEmuna, 1:4