I'd like to clarify my comment on the podcast about how the emphasis on rationality as it regards the afterlife is common to Maimonides and Spinoza.
I'm looking here at a review by Martin Lin of Steven Nadler's book Spinoza's Heresy: Immortality and the Jewish Mind. Now, Nadler is my go-to local Spinoza scholar--you can see him here and here--and he's the guy Seth was referring to who was on Wisconsin Public Radio talking about Spinoza's excommunication.
According to the review, Spinoza was excommunicated largely for denying the immortality of the soul. ...Meaning that canon Judaism at the time affirmed this immortality, and Maimonides's view here is characterized initially as maintaining that "the soul can live on after death, retaining, however, only its intellectual powers." However, as Nadler looks more closely at Maimonides, this kind of immortality looks like weak tea compared to a Christian heaven:
...According to Aristotelian metaphysics, substances are individuated by their matter. How then can souls be individuated after the death of the body? The response famously offered by Aristotle’s great Arabic interpreter Averroes is that they can’t, and hence all souls are one after the death of the body. How to both avoid Averroism and embrace incorporeal immortality is an issue that plagued Christian and Jewish Aristotelians of the Middle Ages. According to Nadler, the immortality of the soul in Maimonides amounts to nothing more than the persistence of the acquired intellect, the state of the soul when it acquires knowledge. This seems to reduce the immortality of the soul to the persistence of an abstract body of knowledge. So how can Maimonides have a theory of personal immortality as he insists he does? According to Nadler, this intellectualistic and not very personal account of immortality is extended further by his disciple Gersonides... souls are individuated by their differential levels of intellectual achievement. For example, if in this life I acquire knowledge of p and q, and you acquire knowledge of p, q, and r, then after death our souls are distinguished by the presence of knowledge of r in your soul and the absence of such knowledge in mine. As Nadler notes, this is a very tenuous conception of personal immortality, not least of all because there is nothing to guarantee that two people will not be identical with respect to their intellectual accomplishments and hence be indistinguishable after death.
Spinoza's view is more complicated. He says "The human mind cannot be absolutely destroyed with the body but something of it remains which is eternal... This eternal part is: An idea which expresses the essence of the human body, sub specie aeternitatis, and which pertains to the essence of the human mind."
However, you'll recall from our Spinoza discussion that mind and body are two aspects of the same thing, so the mind living on after the body wouldn't make any sense. Lin characterizes Nadler's answer:
The essence of the mind is eternal, to be sure, but that’s not what Spinoza’s talking about when he says that we can bring it about that the greater part of our mind is eternal. What he is referring to is the adequate knowledge that the mind possesses. This part can be enlarged by acquiring more knowledge. Adequate ideas represent their objects sub specie aeternitatis. Because they are adequate they are in God insofar as he constitutes the human mind. That is to say, there is no ontological difference between an adequate idea in the human mind and an adequate idea in God’s mind. So the ideas by which we have adequate knowledge are eternal, and the more of them we possess, the greater part of our mind is eternal.
So (and this I think matches our take during the second part of our Spinoza discussion), yes, the immortality in Spinoza is not a matter of my existing as in individual after death, but my right now as a reasoning being taking part in God, and so those parts of my mind being immortal. This is pure Platonism: we partake of the universal by a certain kind of non-sensuous mental activity.
So yes, reason is relevant to both M. and S. in their views of immortality, and the views are similar in that they're both kind of hard to figure out and fall somewhere in between death-is-the-end and let's-go-meet-grandma-in-heaven, but they've pretty distinct given that the two figures have different metaphysical views that have to be reconciled with any kind of immortality. And I promise we'll do Aristotle's metaphysics before the end of the year so that will be clearer.