A scientifically testable hypothesis must make predictions that can be tested. The hypothesis should predict something that is likely to happen, and something that is unlikely to happen if the hypothesis were true. The predictions must have the property that they can be validated by independent observers. Furthermore, the predictions must be unique if one is to distinguish between alternative hypotheses.
One could ask if the existence of the jīva in the body is scientifically testable (that ātman which identifies with the material body is called jīva). Here we examine this question by analyzing the properties of the jīva given by Jiva Goswami in the Paramātma Sandarbha, which may be considered as predictions of the jīva hypothesis:
The jīva is conscious and not inert
Here a distinction is being made between the jīva and the material manas, citta, buddhi and physical body. This prediction is not testable because to test it, one would have to take the jīva out of the body in a controlled way, and observe the body lose consciousness; or one would have to introduce the jīva into unconscious matter, and observe matter gain consciousness. Neither of these are possible, of course, because the jīva is not a physical entity- it has no dimension (see below) – and cannot be manipulated by external observers.
The jīva is eternal, free from modification and uniform
The body changes during the process of aging, and the mind changes according to the information it has received, but the jīva does not undergo any modification. Often the point is made that our ego or the thought, “I am this person” does not change, even though the body changes significantly from childhood to old age. Of course, such ideas do not constitute scientific evidence, because they are not a unique prediction of the jīva hypothesis. It is easy to program a computer to retain some fixed memory over a period of time, even while the information in its hard drive is modified continually. An example is the computer’s clock. Human memory works by an analogous process: memories are formed over time without loss of older memories. It is no surprise that a person retains the notion of “I am this person” over their entire life.
The scientific method generally provides evidence for the unobservable through the process of inference. However, inference doesn’t work with the jīva. For example, even though the jīva possesses the capacity for being an agent of action, and capacity for thought, it cannot manifest these capacities in the absence of a mind and body. Whenever a thought occurs, or an action takes place, it occurs in the mind and body, not in the jīva, which is free from such modifications. What an observer can observe is thought in the mind (inferred through electrical signals in the brain) and the motion of muscles that enable actions; all of which are attributable to molecular pathways in cells. The jīva is superfluous for explaining the body and mind’s functionings.
Similarly, the eternality of the jīva is not a scientific hypothesis, because the jīva’s eternality is not inferable from the body nor in any related measurable phenomena.
Uniformity implies that the qualities of the jīva do not change with time. Again, something that doesn’t change with time, and does not manifest its timeless effects in the body, cannot be scientifically inferred from an experiment that must take place in time.
The jīva is not mere consciousness
This means that the jīva has the intrinsic capacity to perceive or know other objects. However, this capacity is only actualized when the jīva identifies with the mind. All knowing of objects is a function of the mind, and the jīva remains unmodified. The functioning of the mind is clearly a scientifically inferable process, but the jīva’s presence is not detectable in this functioning, given that the jīva itself undergoes no modification, and ultimately ‘knows’ nothing.
The jīva is self-conscious and self-luminous
The jīva illuminates itself- that is, it knows it exists. The jīva cannot transmit this information to others without the mind-body complex, or even understand its own existence without the mind. Therefore it is not possible to discriminate between self-consciousness as the jīva’s intrinsic energy, as opposed to simply being the mind’s function.
The jīva is the direct meaning of “I”
There are two types of “I-ness”- one is the intrinsic property of the jīva, and the other is the property of inert ahaṅkāra. The jīva’s intrinsic I-ness is superimposed on the I-ness of ahaṅkāra. When the ordinary jīva says “I am”, it means it is the body, or it is the mind, because only when there is ahaṅkāra can the jīva say anything about itself. Even when the jīva in the body articulates the following: “I am not this body, and I am not this mind”, this knowledge is also a modification of the mind that is expressed through the body. Therefore, to an external observer, it is not possible to distinguish between the jīva’s intrinsic I-ness, and the I-ness of the mind-body complex. Again, a computer could be easily programmed to say “I exist”.
The jīva is devoid of misery and is of the nature of happiness
The jīva is intrinsically free of all pain, unhappiness, sadness or misery. This freedom can be only experienced in deep sleep. However, in deep sleep, the brain is also not functional in its cognitive sense, so one can equally explain the lack of awareness of pain this way. Note that none of the jīva’s qualities so far make unique, testable predictions that cannot simply be attributed to the mind-body complex.
The jīva is distinct in each body and atomic in size
One of the jīva’s properties is that it is aṇu, which can be loosely translated as ‘atomic’. This is a technical term in nyāya which means that the jīva has no parts, it has no form, and has no dimension. The jīva cannot be detected, say with a microscope, as it has no physical dimension. Therefore, this property is not scientifically testable.
The jīva has knowership, agency and enjoyership
Again, none of these properties of the jīva can manifest without the mind and body. It is not possible to detect the pure jīva acting, knowing or enjoying, because it cannot do any of these things in its pure state. Discriminating between functions of the mind-body complex and of the jīva is not possible.
The jīva is part of Paramātmā
This cannot be tested because the Paramātmā is beyond the capacity of the senses to perceive. On this note, the jīva is also beyond the capacity of the mind and senses to perceive, because the jīva is subtler than these. Similarly, sense objects cannot detect the senses, and the senses cannot detect the mind. Unsurprisingly, the jīva is beyond detection by the scientific method.
Overall, many of the jīva’s properties cannot be tested independently from those of the mind-body complex, because its properties can only be manifested through the mind-body complex. Other properties like eternality will always be untestable in a scientific sense.
Many people point to studies of the reincarnation type that suggest memories from previous lives as proof of the jīva. Independent of whether such studies are true (I haven’t seen scientifically sound evidence yet), such evidence can at best attest to the continuity of the citta (mind) between past and present lives. They say nothing about the existence of the jīva.