J. C. C. McKinsey, A. C. Sugar and P. Suppes (hereafter MSS) wrote “Axiomatic foundations of classical particle mechanics”, (*Journal of Rational Mechanics and Analysis*, v.2 (1953) p.253-272), which is also described in Suppes’ *Introduction to Logic* (Van Nostrand, New York, 1957), pp.291-322 (see *here*). It is only a partial axiomatization of Newtonian mechanics but is sufficient to present an involution of mechanics below.

An involution in mathematics is a function that is its own inverse, which means if it is repeated the output is the input, that is, *f*(*f*(*x*)) = *x*. The involution here is the interchange of spatial and temporal quantities along with the inversion of mass. We start with MSS:

MSS system has six primitive notions: *P, T, m*, **s**, **f**, and **g**. *P* and *T* are sets, m is a real-valued unary function defined on *P*, **s** and **g** are vector-valued functions defined on the Cartesian product *P* × *T*, and **f** is a vector-valued function defined on the Cartesian product *P* × *P* × *T*. Intuitively, *P* corresponds to the set of particles and *T* is to be physically interpreted as a set of real numbers measuring elapsed times (in terms of some unit of time, and measured from some origin of time). *m*(*p*) is to be interpreted as the numerical value of the mass of *p* ∈ *P*. **s**_{p}(*t*), where *t* ∈ *T*, is a 3-dimensional vector which is to be physically interpreted as the position of particle *p* at instant *t*. **f** (*p,* *q,* *t*), where *p, q* ∈ *P*, corresponds to the internal force that particle q exerts over *p*, at instant *t*. And finally, the function **g**(*p,* *t*) is to be understood as the external force acting on particle *p* at instant *t*. (*Anna & Maia* p,9)

We define MSS´ by the following involution: interchange *P* and *Q*; *p* and *q*; *T* and *S*; *m* and *n*=1/*m*; **s** and **t**; **f** and **k**; **g** and **ℓ**; particle and insticle; instant and point; mass and vass. Then the explanation is:

MSS´ system has six primitive notions: *Q, S, n*, **t**, **k**, and **ℓ**. *Q* and *S* are sets, *m* is a real-valued unary function defined on *Q*, **t** and **ℓ** are vector-valued functions defined on the Cartesian product *Q* × *S*, and **k** is a vector-valued function defined on the Cartesian product *Q* × *Q* × *S*. Intuitively, *Q* corresponds to the set of insticles and *S* is to be physically interpreted as a set of real numbers measuring arc length (in terms of some unit of length, and measured from some origin point). *n*(*q*) is to be interpreted as the numerical value of the vass of *q* ∈ *Q*. **t**_{q}(*s*), where *s* ∈ *S*, is a 3-dimensional vector which is to be physically interpreted as the position of insticle *q* at point *s*. **k**(*q,* *p,* *s*), where *q, p* ∈ *Q*, corresponds to the internal surge that insticle p exerts over *q*, at point *s*. And finally, the function **ℓ**(*q,* *s*) is to be understood as the external surge acting on insticle *q* at point *s*.

The corresponding axioms are as follows:

A1 *Q* is a non-empty, finite set.

A2 *S* is an interval of real numbers.

A3 If *q* ∈ *Q* and *s* ∈ *S*, then **t**_{q}(*s*) is a 3-dimensional vector (**t**_{q}(*s*) ∈ℜ³) such that *d*²**t**_{q}(*s*)/*ds*² exists.

A4 If *q* ∈ *Q*, then *n*(*q*) is a positive real number.

A5 If *p,* *q* ∈ *Q* and *s* ∈ *S*, then **k**(*p,* *q,* *s*) = −**k**(*q*; *p*; *s*).

A6 If *p,* *q* ∈ *Q* and *s* ∈ *S*, then **t**_{q}(*s*) × **k**(*p, q, s*) = –**t**_{p}(*s*) × **k**(*q, p, s*).

A7 If *p,* *q* ∈ *Q* and *s* ∈ *S*, then *n*(*q*) *d*²**t**_{q}(*s*)/*dt*² = Σ_{p∈Q} **k**(*p, q, s*) + ℓ(*q, s*).

These axioms generate a dual to Newtonian mechanics. A5 corresponds to a weak dual version of Newton’s Third Law: to every surge there is always a countersurge. A6 and A5, correspond to the strong dual version of Newton’s Third Law. A6 establishes that the direction of surge and countersurge is the direction of the line defined by the coordinates of insticles p and q. A7 corresponds to the dual of Newton’s Second Law.

MSS show that mass is independent of the remaining primitive notions of their system. Because of this, its dual could be defined differently. It was thought best to take the inverse of mass, called vass, for the involution.