Newton believes space exists independently of and distinct from all bodies. He names this revolutionary and controversial idea of absolute space. With absolute space, Newton’s theories regarding space continue permitting relative space like past philosophers to define an object’s location through comparisons to other objects’ locations. What makes Newton’s idea on space unique is that Newton adds a standard metric—absolute space. It constantly and absolutely serves as the metric for determining these objects’ locations. Although one can still use relative space to do so, absolute space is a superior and more consistent tool than relative space by always assigning each body an absolute description of its location-based on absolute space and the object’s relative locations. To Newton, there is one true motion for each body because absolute space always and absolutely defines where the object is and how the object moves. In addition, Newton interestingly thinks space, the “sensorium,” is what God uses to perceive things in the universe.
Leibniz, on the other hand, acknowledges true motion’s existence but argues that absolute space doesn’t exist and cause true motion. He believes true motions originate from inherent true forces inside the body and are defined by God through relative space and these forces. Also, he disagrees with Newton that God will ever necessitate a “sensorium” to perceive the world because if Newton maintains that God is an omnipotent, eternal, and omnipresent creator, it is inconsistent to say that God is actually dependent on anything—here Leibniz means space—and the existence of “sensorium” implies that God didn’t create the universe.
Leibniz uses the principle of sufficient reason (PSR)—God won’t do anything without a sufficient reason—to attack the necessity of God’s creation of absolute space. He lists Clarke’s argument that bases on two premises and attacks the second premise by analyzing why God has no sufficient reason to create a universe with it. Clarke thinks: (1) space is the same everywhere; (2) space is absolutely omnipresent and independent of objects in the universe. They lead to Leibniz’s question: (3) Why would God have a sufficient reason to enable (2) if its only utility value is for God to rotate the entire world’s axis? This insignificant change in metric doesn’t substantially facilitate God’s definition of objects’ locations and relations in any way or modify/improve how objects behave in the universe. Therefore, Leibniz finds (2) excessive. God has no sufficient reason to implement it.
While Leibniz argues the powerful but functionally insignificant absolute space is excessive in assisting operations of the universes, he proposes a simpler definition of space with no excessive properties like universal presence and independence like (2). His alternative (2) explains the material universe just as well. It says that space is only a “set of relations among bodies” and a possibility for bodies to be situated in the material universe, deriving from the framework of relative space. In this universe, God can place objects in empty spaces and define their motions with their inherent forces and relative locations. One possible objection to this is relative space cannot explain the phenomenon of Newton’s bucket. Leibniz can respond that a relative space form of absolute space is gauging motions in a smaller scale at a designated part of the universe, like the center of the galaxy/solar system.
Leibniz thinks this non-absolute definition of space will do for God because it illustrates an indiscernible universe from Clarke’s. Leibniz’s universe equips God with relative space, a tool as competent as absolute space, to regulate objects’ locations, and functions like how humans experience Clarke’s universe (i.e. physical laws will manifest themselves similarly).
To elaborate on why Clarke and Leibniz’s universes are indiscernible I will compare them. For example, Universe A (Clarke and Newton’s) has absolute space, in which allows God to have an absolute ruler that always assigns a standard value to describe an object’s motion. Universe B has no absolute space, in which God can still perfectly describe objects’ motions by including “inherent forces” and comparing the object to others. God can perfectly place and identify objects’ locations in both universes, so God has no sufficient reason to apply absolute space. Also, everyone will live in these two universes and experience life similarly (i.e. airplanes fly the same or someone travels one hundred feet after he/she gets hit by a car traveling at 100 miles/hr in both Universe A and B), although A and B utilize different metrics (A has an absolute metric and B has a relative metric) that are functionally the same to distinguish among their motions. The lack of substantial convenience and consequential functional differences provided by absolute space supports Leibniz’s point that if God follows PSR, it won’t have sufficient reasons to create our universe like Universe A rather than Universe B.
As Leibniz has shown that Newton’s Universe and his Universe have no substantial difference for either God’s purposes or humans’ lives, he believes God has no sufficient reason to permit the possibility of “two states,” which are functionally the same and differentiated only by whether either possesses absolute space. These two worlds are not so different to God. In both, God can regulate motions efficiently, so it won’t consider applying absolute space due to PSR. Therefore, that philosophers are debating whether absolute space exists, the controversial difference “to be found in our chimerical supposition of the reality of space,” is ludicrous and excessive because to God, absolute space enables no consequential difference to the universe itself and how the universe functions and affects its objects. It’s like debating whether God will prefer an artificially colored apple to a naturally colored apple.
After presenting why absolute space is inconsequential to God’s work and people’s experience of the physical reality, Leibniz concludes that if both universes are functionally the same, like I explained above, except their locations and times of creation, they are twins. If God needs to choose between these twin universes, it’s an impossible fiction. What he means here by “impossible fiction” is that the extreme similarity between two objects renders God no room for a choice backed by sufficient reasons. This is logically impossible if philosophers agree that God’s criteria for creative works are: (1) God is omnipotent; (2) God follows the principle of sufficient reason when it does things. The twin universe scenario violates (2) because God possesses no convincing reason to pick one over the other. Thus, God will never place himself in a creation scenario in which he must choose between two extremely similar universes. God will create the leanest universe—the laws of nature will be as efficient as effective as possible. However, it is not physically impossible because God is omnipotent in the physical universe, so God can do whatever it wants, including creating two twin universes and randomly making a choice–it simply won’t do this because God is rational (PSR). It is not metaphysically impossible either. If we define metaphysical activities are what cannot be done without transcending the laws of nature, God can do it because God, again, is omnipotent and able to violate physical laws to create if it wills.
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