An argument from “Tamim tihye”

(“You shall be wholehearted with Hashem”)

An interesting argument advanced is that heeding the warnings of climate science would constitute a violation of the Torah’s requirement to “be wholehearted with Hashem your God”. What does this mean?

Let us look at the broader context in which this statement appears:

When you enter the land that Hashem your God is giving you, you shall not learn to imitate the abhorrent practices of those nations. Let no one be found among you who consigns his son or daughter to the fire, or who is an augur, a soothsayer, a diviner, a sorcerer, One who casts spells, or one who consults ghosts or familiar spirits, or one who inquires of the dead. For anyone who does such things is abhorrent to Hashem, and it is because of these abhorrent things that Hashem your God is dispossessing them before you. You must be wholehearted with Hashem your God. Those nations that you are about to dispossess do indeed resort to soothsayers and augurs; to you, however, Hashem your God has not assigned the like. Hashem your God will raise up for you a prophet from among your own people, like myself; him you shall heed. (Devarim 18:9-15)

From the context, it appears that being “wholehearted with Hashem” means not putting your faith in fortune-tellers, but in Hashem and the prophets He will send you.

What about at a time in history when there are no longer prophets to consult, like today? Does this obligation still apply? Rashi explains the principle as follows:

Walk before him whole-heartedly, put your hope in Him and do not attempt to investigate the future, but whatever it may be that comes upon you accept it whole-heartedly, and then you shall be with Him and become His portion.

It sounds like even when there are no prophets, one must continue to fulfill this principle by placing one’s trust in Hashem wholeheartedly and refraining from investigating the future. Through displaying this trust the Jewish people will become bonded with Hashem.

What does this involve practically?

The example of genetic testing

One of the practical scenarios in which this principle is discussed is in the context of dating couples or individuals undergoing genetic testing to determine whether they carry genes for congenital diseases, such as Tay-Sachs. Halachic authorities were asked, among other considerations, whether undergoing such tests are in violation of the principle of ‘Tamim tihye’.

Rav Moshe Feinstein’s position is the one agreed to by most poskim. In his response he stated:

Even though there is a very small minority of children born [with these conditions], such that it would be appropriate to apply in this context the verse of ‘Tamim tihye im Hashem Elokecha’, and as Rashi expounds it: “Walk before him whole-heartedly, put your hope in Him and do not attempt to investigate the future”, nevertheless, since this is now done in a way whereby it is easy to check, there is room for discussion as to whether one who does not check himself is considered like one who closes his eyes from seeing what is possible to see. And since if, G-d forbid, something like this [the birth of such a child] were to happen, it would cause tremendous suffering, it is appropriate that those who are looking to marry should be tested. (Igros Moshe, Even HaEzer 4:10)

Rav Moshe points out that ‘Tamim tihye’ would only apply where the level of risk in an individual case is small. Furthermore, it would only be a problem if one exerted oneself to investigate the future, as opposed to where the information is freely available.

If we assume that using climate science to investigate the future is problematic from the perspective of ‘Tamim tihye’ and that a frum Jew must not be involved in it, that has no bearing on our reliance on that research, because the investigation is already being done. As such, for us to ignore their predictions would be, in Rav Moshe’s words, to “close one’s eyes from seeing what is possible to see”.

Furthermore, Rav Moshe implies that ‘Tamim tihye’ only applies in cases where the risks involved are small, although he doesn’t elaborate on how small or on the reasoning behind this understanding. Perhaps, if the risks are high, the principle of ‘Venishmartem me’od l’nafshoteichem’ (‘you shall protect your lives greatly’) comes into play and overrides its application. As such, given the heightened risks of danger associated with climate change, it seems unlikely that predictive climate research would be problematic even for a Torah-observant Jew.

Keeping the spirit of ‘Tamim Tihye’

Although technically, it would seem that ‘Tamim tihye’ poses no problem for accepting the findings of climate science, it was suggested that relying on climate modeling, which plays a major role in climate research, is inconsistent with the spirit of ‘Tamim tihye’ as understood by the Rishonim (medieval rabbinic authorities). Let us examine the different approaches to understanding this principle.

The view of the Rambam

In the Rambam’s view, the Torah forbade consulting soothsayers and other similar sources, because they reach conclusions which are unreliable and foolish, and it is not fitting for the Jewish people to follow nonsense (Mishneh Torah, Hilchos Avoda Zara 11:17). Predictions of the climate are certainly not an exact science and opinions vary greatly about how things could unfold. Would the Rambam therefore lump climate predictions in the same category as soothsayers?

It’s important to realize that although climate modeling is not an exact science, the hundreds of climate scientists worldwide who have earned doctorates in the field, who have been involved in postdoctoral research full-time for many years, if not decades, who publish articles which are subjected to intensive peer review, are quite aware of what climate models can and cannot do. They do not confidently put their faith in whatever prediction a climate model spits out. They make use of models to better understand how different physical systems interact with each other, but this is certainly a far cry from visiting a soothsayer.

The view of the Ramban

The Ramban has a very different understanding of the problem with consulting soothsayers and the like. Even if they are completely reliable, Hashem wants us to trust in Him and only seek knowledge of the future from His messengers, rather than in these foreign methods which alienate us from Hashem (Commentary to Devarim 18:13). If so, could it be that using scientific methods, even if they gave accurate results, would be out of bounds to the Jewish people?

To this end, it’s important to clarify what we mean by predicting the future. As different as they are, what a prophet of Hashem and a soothsayer have in common is that they both purport to tell the future. If that’s what a climate scientist did, perhaps that would be a problem. The fact is that it is not.

A climate scientist uses the best data available about the climate and our best understanding of the physical processes to try and understand the various possible outcomes that could unfold and tries to assess the probabilities of each of these outcomes occurring. Such an approach is commonly employed in many fields in which Torah-observant Jews engage, such as in stock market analysis, actuarial analysis, business risk management, healthcare planning and military strategic planning, without raising an eyebrow.

Watching the situation unfold

Another reason why Tamim tihye should not be relevant here is that climate science is studying trends that are already unfolding and damage that is already taking place. Once there are signs that a dangerous situation is developing, it is difficult to argue that Hashem would insist on not exploring any further.