The Mind as Computer Metaphor: Benson and the Mistaken Application of Mental Steps to Software (Part 5)

Go to: Part 1, Part 2, Part 3, Part 4, Part 5

(This series of posts is based on an upcoming paper for the AIPLA Spring 2016 meeting.)


The fictional form of the mental steps doctrine is inapplicable to digital computers and computer-implemented inventions for several reasons.

First, prior to the widespread usage of the general purpose computer, many inventions were created, and many patents granted, for mechanical and electrical machines that performed mathematical calculations. For example, between 1900 and 1960, there were over 2,300 patents issued that related to mechanical computing devices. That such devices were patent-eligible subject matter seemed beyond dispute, and there are no federal cases in which claims to such devices or their methods of operation were held to be unpatentable subject matter. Calculating machines also perform simple arithmetic that a human could easily do by “head and hand”, but that does not disqualify them as patentable subject matter. This is because the mathematical operations had been mechanized into physical elements: the “locus of the operation” was in the mechanical or electrical elements of the machine.

Most calculating machines typically could only perform individual mathematical operations such as addition, subtraction, multiplication, division, logarithm, and so forth. Performing a complex series of mathematical calculations, therefore, required the human operator to control the sequence and execution of a series of calculations, as well as in many cases to store, typically on a notepad, intermediate results for later entry into the machine. In short, even though the locus of the operation was in the machine, the locus of control in those devices was always in the mind of the human operator, whether he was using a desk calculator, a slide rule, or an abacus. Accordingly, in patent cases decided prior to the widespread application of computers, the courts were correct to hold that a claim to mathematical procedures or use of formula was essentially one for mental steps, because there was then no known way to have a machine perform the entire mathematical process automatically.

However, von Neumann’s architecture of the stored program computer represented a fundamental change in where control of the operations is held. Prior to the von Neumann architecture, a human had to enter a program one step at a time into the computer’s memory—this was essentially the same as the human controlling the adding machine by pressing keys and pulling handles. In the stored program computer, the locus of control resides in the machine itself: the computer program controls the operation of the computer by sequentially changing the signals stored and manipulated by the computer, without any human intervention other than high level inputs. These low level signals are not representative of the mental states of the human but rather are signals that electronically represent the machine language “instructions” that the computer can execute. At a minimum, just as the mechanical or electrical implementation of calculating machines would not be ignored in deciding patent eligibility, the implementation of a digital computer should not be ignored either.

The only reason to ignore the presence of digital computer elements, such as the shift register in Benson, or even a general-purpose computer itself, is if one assumes that computers perform mental steps in the same way that a human does. Once this assumption is removed, there is no principled reason to distinguish between the mechanical nature of a calculating machine and the computer technology in digital computers. Both likewise contribute to patent eligibility. And as shown above, the assumptions of functional and procedural equivalence was without support in Benson in 1972 and remains even less likely today.

The fictional form of the mental steps doctrine represents a significant and unwise departure from the factual form. The fictional form is untethered from the conceptual and technological attributes of computer design, the nature of human cognition, and the practical reality and value in computer-implemented inventions. The courts should return to the doctrine’s factual form, and avoid a further descent into the fact-free analysis that now characterizes patent eligibility.

*The perspectives expressed in the Bilski Blog, as well as in various sources cited therein from time to time, are those of the respective authors and do not necessarily represent the views of Fenwick & West LLP or its clients.